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Study of Fiber Reinforced Polymer Materials in
Reinforced Concrete Structures As Reinforced Bar
SEMINAR-I
REPORT
Girish Kumar Singh SPA/NS/BEM/612
IInd SEMESTER
DEPARTMENT OF BUILDING ENGINEERING AND MANAGEMENT
SCHOOL OF PLANNING AND ARCHITECTURE
New Delhi – 110002
MAY 2015
CERTIFICATE
Certified that this Project Seminar titled "Study of Fiber Reinforced Polymer Materials in
Reinforced Concrete Structure As Reinforced Bar" submitted by Er. Girish Kumar Singh in
partial fulfillment for the award of the degree of Master in Building Engineering and
Management at the School of Planning and Architecture, New Delhi, is a record of student's
work carried out by him under my supervision and guidance. The matter embodied in this
seminar work, other than that acknowledged as reference, has not been submitted for the
award of any other degree or diploma.
Prof. Dr.V.Thiruvengadam Prof. Dr. V.K. Paul
Visiting Faculty & Seminar Guide Prof. & Head of the Department
Building Engineering & Management Building Engineering & Management
School of Planning and Architecture. School of Planning and Architecture
New Delhi. New Delhi
ACKNOWLEDGEMENT
I would like to sincerely thank Prof. Dr. V.K. Paul, Head of the Department of Building
Engineering and Management, Prof. Kuldeep Chander, for helping in successfully
completing the seminar work.
I take this opportunity to express my gratitude to my guide, Prof. Dr.V.Thiruvengadam,
faculty, Department of Building Engineering and Management, for his constant and generous
support throughout the Seminar. His inputs and guidance proved vital to shape the Seminar
in the desired form.
My sincere thanks to Prof. Dr. V.K. Paul, Head of the Department of Building Engineering
and Management, for his valuable suggestions at various stages in the Seminar work.
I thank my family, Mom & Dad, for believing in me and incessantly encouraging me to take
up this course. They are and shall always be my greatest source of strength and a belief in
myself. May I always stand tall to all their expectations and excel beyond their dreams.
New Delhi
May 2015 Girish Kumar Singh
ABSTRACT
Around the world we are having several upcoming projects near the coast line so the
study is needed to understand the effect on cost when we use FRP in the structure because FRP
is a costly material compare to steel which may or may not increase the structure overall cost.
It will may or may not increase the structure cost because if we use FRP in a structure then we
can avoid the problem that we face in a structure caused due to corrosion which reduce strength
of the structure, foundation loosing plaster from the surface of the reinforced section due to
expansion caused due to rusting as well as in building envelopes.
The objectives of this seminar report are to study about FRP Manufacturing and its properties,
study about the various applications of FRP, design and analyze a FRP member, Finite element
analysis of a simple beam using FRP as a reinforcement, role of FRP in the sustainable world,
to find out the cost benefit of the elements used in a corrosive environment structure which can
be replaced by the FRP.
This study will cover all the forms of FRP that can be used in a building and give a brief about
FRP rebars its properties, design, analysis, uses and the effect on cost of a build during
construction as well as the cost analysis of the structure.
This study will give an idea on the advantage of FRP over steel when we are using FRP in a
corrosive environment like coast line and it will give an initial idea to the designer about the
advantage and disadvantage of FRP over steel.
In the final part of this seminar report analysis results are used to give a base that FRP can
sustain in structure as FRP reinforced bar and an example of a LCC is also used to give a
satisfactory conclusion and on the final page the summery of the seminar is present.
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Contents Chapter 1 - Introduction ................................................................................................................................. 6
1.1 General ................................................................................................................................................. 6
Table 1.1 Merit Comparison and Ratings for FRP and Steel ........................................................................ 9
Table 1.2 FRP Merits and Suitability of Applications .................................................................................. 9
Table 1.3 FRP Use and Suitability for Marine Applications ....................................................................... 10
1.2 Need of Study ..................................................................................................................................... 11
1.3 Aim ...................................................................................................................................................... 11
1.4 Objectives ........................................................................................................................................... 11
1.5 Scope of study ..................................................................................................................................... 11
1.6 Methodology ....................................................................................................................................... 12
1.7 Seminar Organization ............................................................................................................................. 12
Chapter 2: Literature Review....................................................................................................................... 15
1. General ........................................................................................................................................... 15
2. Codes & Published Papers .................................................................................................................... 15
2.1 State-of-the-Art Report on Fiber Reinforced Plastic (FRP) Reinforcement for Concrete Structures (ACI 440.04r, 2002) ................................................................................................................. 15
2.2 Serviceability of Concrete Beams Prestressed By fiber Reinforced Plastic Tendons (By Amr. A Abdelrahman1995) .................................................................................................................................. 16
2.3 Retrofitting of Existing Bridge Using Externally Bonded FRP Composite Applications and Challenges (MEDIA) .................................................................................................................................. 16
2.4 The role of FRP composites in a sustainable world (Jain, 2009) ................................................ 17
2.5 Bridge decks of fibre reinforced polymer (FRP): A sustainable solution ................................. 18
2.6 Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (440, Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, 2008) ....................................................................... 18
2.7 Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars (ACI 440, 2006) ........................................................................................................................................... 19
Chapter : 3 Materials Introduction (FRP) .................................................................................................. 20
3.1 History ............................................................................................................................................ 20
3.2 Manufacture Process ..................................................................................................................... 22
3.2.1 General ................................................................................................................................... 22
3.2.2 Manufacturing Process ................................................................................................................. 23
3.2.3 Fibre ................................................................................................................................................ 23
3.2.4 Forming processes ................................................................................................................. 26
• Glass fibre material ....................................................................................................................... 30
• Carbon fiber ................................................................................................................................... 30
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 1 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
• Aramid fiber material ................................................................................................................... 31
3.6.1 Corrosion Resistance ..................................................................................................................... 31
3.6.2 High Strength, Lightweight .......................................................................................................... 32
3.6.3 Dimensional Stability .................................................................................................................... 32
3.6.4 Parts Consolidation and Tooling Minimization. ......................................................................... 32
3.6.5 High Dielectric Strength and Low Moisture Absorption ........................................................... 32
3.6.6 Minimum Finishing Required ...................................................................................................... 32
3.6.7 Low to Moderate Tooling Costs ................................................................................................... 32
3.6.8 Design Flexibility ........................................................................................................................... 32
3.6.9 Thermal conductivity .................................................................................................................... 33
3.6.10 EMI /RFI Transparency ............................................................................................................... 33
3.6.11 Physical properties ......................................................................................................................... 33
• Density ............................................................................................................................................ 33
• Coefficient of thermal expansion .................................................................................................. 33
3.6.12 Mechanical properties and behavior ........................................................................................... 34
• Tensile behavior ............................................................................................................................. 34
• Compressive behavior ................................................................................................................... 36
• Shear behavior ............................................................................................................................... 38
• Bond behavior ................................................................................................................................ 38
3.6.13 Time-dependent behavior ............................................................................................................. 39
• Creep rupture ................................................................................................................................ 39
• Fatigue ............................................................................................................................................ 40
• Effects of high temperatures and fire ........................................................................................... 43
3.6.14 Chemical Properties ...................................................................................................................... 44
3.7 Applications .................................................................................................................................... 45
3.7.1 Applications of FRP Composites in Industrial Construction ............................................ 45
3.7.2 Application of FRP Composite Systems in Strengthening . ....................................................... 47
3.7.3 Army, Marine, and Related Applications ............................................................................ 51
3.7.4 FRP Pipes for Marine Applications ..................................................................................... 52
3.7.5 FRP Piling .............................................................................................................................. 53
3.7.6 Other FRP applications ......................................................................................................... 54
3.7.7 FRP Design, Development and Field Implementation by CFC-WVU and Others .......... 55
3.7.8 Application of FRP as Rebar ................................................................................................ 57
Chapter 4 Code Provision ............................................................................................................................. 59
1.1 Standard test methods for FRP bars and laminates ................................................................... 59
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 2 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Chapter 5 Manual Design of FRP Beam ..................................................................................................... 61
Chapter 6 Analysis of Beam Using FEM .................................................................................................... 74
Finite element model of concrete SOLID65 Description: ...................................................................... 76
SOLID65 ................................................................................................................................................. 76
Input Summary ...................................................................................................................................... 77
LINK8 Input Summary ......................................................................................................................... 78
Chapter 7 Costing .......................................................................................................................................... 92
INTRODUCTION ........................................................................................................................................... 92
View of the Okinawa Road Park Bridge ...................................................................................................... 93
THE STRUCTURES FOR THE CASE STUDY............................................................................................. 93
Model cases of FRP and PC bridges ............................................................................................................ 94
FRP footbridges ......................................................................................................................................... 95
Table 2: Model cases of PC bridges and initial costs (Unit: 1000JPY) .................................................. 96
Table 3: Model cases of FRP bridges and initial costs (Unit: 1000JPY) .............................................. 96
CASE-4 ........................................................................................................................................................ 96
CASE-5 ........................................................................................................................................................ 96
Modified points for the superstructure ......................................................................................................... 96
Standard FRP bridge based on the real bridge ............................................................................................. 96
Aluminum handrail ...................................................................................................................................... 96
Change of joint parts of the main girders ..................................................................................................... 96
Sharing the mold by 2 bridges ..................................................................................................................... 96
Initial cost for the superstructure .................................................................................................................. 96
73,600 96
62,350 96
Substructure system ..................................................................................................................................... 96
Pier 1: 2 Steel pipe piles (φ500mm-9mm, L=15.0m) ................................................................................... 96
Pier 2: 4 Steel pipe piles (φ500mm-9mm, L=18.0m) Pier 3: 2 Steel pipe piles (φ500mm-9mm, L=12.0m) 96
Initial cost for the substructure ..................................................................................................................... 96
6,910 96
Total Initial costs.......................................................................................................................................... 96
80,510 96
69,260 96
Maintenance costs ...................................................................................................................................... 97
FRP footbridge ........................................................................................................................................... 97
LCC 98
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 3 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Table 4: LCC results of both PC and FRP footbridges (Unit: 1000JPY) ............................................... 99
CONCLUSION ................................................................................................................................................ 99
Chapter 8 Summery .................................................................................................................................... 101
Bibliography ................................................................................................................................................... 102
LIST OF FIGURE
Figure 1 Formation Process Of FRP ............................................................................................................ 22
Figure 2 Structure of FRP ................................................................................................................................ 23
Figure 3 Stress Strain Curve Fro FRP ........................................................................................................ 36
Figure 4 FRP Pultruded sections and chemical platform with these products ........................................ 46
Figure 5 FRP composite tanks: a – horizontal tanks [7]; b – vertical tanks [8]. ...................................... 46
Figure 6 Large scale GFR polyester dome and skylight. ........................................................................... 46
Figure 7 Folded skylight on an industrial workshop; double curved shells for an industrial roof. ....... 47
Figure 8 – a – Blades made of glass fibre reinforced polymer (GFRP) [4]; b – FRP composite
components for an offshore platform [6]. .................................................................................................... 47
Figure 9 Strengthening solutions using FRP based solutions for an industrial hall: a – wall
strengthening with bidirectional strips (1) and unidirectional strips (2); b – column strengthening
using discrete strips (3), continuous wrapping (4) and combined discrete and continuous wrapping (5);
c – discrete bending strengthening solutions for reinforced concrete (RC) girders and continuous
membranes (6); d – shear strengthening solutions for RC girders using bottom flange clamping of
inclined strips for runway girders (7) and (8) and U-shaped bands (9); e – strengthening solution for
main transverse girders including end textile clamping (10), plate bonding (11) and discrete clamping
made of composite strips (12); f – plate bonded ribs for roof elements (13). .......................................... 49
Figure 10 Composite based strengthening solutions for industrial chimneys: a – wrapping with
carbon fibre balanced fabric; b – confinement with composite hoop strips; c – helicoidal spiral made
of composite cable; d – prefabricated composite membranes [14]. .......................................................... 50
Figure 11: Very large FRP pipe systems from Future Pipe Industries (www.futurepipe.com) ............. 52
Figure 12 Composite marine piles from different manufacturers were tested. Shown in pictures:
SEAPILE, PPI and Trimax piles, (Juran and Komornik, 2006) ............................................................... 53
Figure 13 Composite marine piles from different manufacturers were tested. Shown in pictures:
SEAPILE, PPI and Trimax piles, (Juran and Komornik, 2006) ............................................................... 54
Figure 14 Boeing 787 Dreamliner, the world's first major commercial airliner to use composite
materials for most of its construction (www.boeing.com) .......................................................................... 54
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 4 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Figure 15 FRP Design and Applications by the CFC-WVU, (Top L to R) – i) FRP dowels in highway
pavement (Elkins, WV), ii) FRP reinforcement for concrete highway pavement (Charleston, WV), and
iii) FRP thermoplastic tie for railroads (Moorefield, WV); (bottom L to R) - i) FRP pavement panels
(Morgantown, WV, iii) thermoplastic FRP offset block for guardrails, (Morgantown, WV) (Courtesy:
CFC-WVU)..................................................................................................................................................... 55
Figure 16 FRP bridge deck shapes designed and field implemented in WV and Ohio by the CFC-
WVU (Courtesy: CFC-WVU) ....................................................................................................................... 56
Figure 17 FRP application for ship decks L); successful testing of fire resistant FRP panel at 5800
degree F with acetylene torch for 5 minute at CFC-WVU. (Courtesy: CFC-WVU) ............................... 56
Figure 18 FRP Inspection Walkway Blennerhassett Bridge, Parkersburg, WV (Courtesy: CFC-
WVU) .............................................................................................................................................................. 57
Figure 19 Examples of FRP application for bridges: (Top L to R)- i) Carbon cables used in bottom
chord, Kleine Emme Bridge, Switzerland (Courtesy: Dr. Urs Meier); ii) FRP pedestrian bridge over
9th Street, NY; (bottom L to R)- iii) Neal Bridge, Maine with FRP tubes (courtesy: NYTimes.com); iv)
Proposed FRP Pedestrian Bridge at West Virginia University, Morgantown) ....................................... 57
Figure 20 Commercially available GFRP reinforcing bars ....................................................................... 58
Figure 21 Solid 65 Geometry ........................................................................................................................ 76
Figure 22 LINK8 GEOMETRY ................................................................................................................... 78
Figure 23 Model Of ANSYS ......................................................................................................................... 88
Figure 24 Model Showing 14.4 kN/m UDL with simply supported at both ends..................................... 89
Figure 25 Nonlinear analysis graph during analysis .................................................................................. 89
Figure 26 Stress along the length of the beam. ........................................................................................... 90
Figure 27 Top stress in the beam.................................................................................................................. 90
Figure 28 Deflection in the beam .................................................................................................................. 91
Figure 29 Initial crack in the beam Figure 30 Final crack of the beam ............................................ 91
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 5 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Chapter 1 - Introduction
1.1 General Fiber-reinforced plastic- FRP is a composite material made of a polymer matrix reinforced with
fibers. The fibers are usually glass, carbon, basalt or aramid, although other fibers such as paper or
wood or asbestos have been sometimes used. The polymer is usually an epoxy, vinyl
ester or polyester thermosetting plastic, and phenol formaldehyde resins are still in use. FRPs are
commonly used in the aerospace, automotive, marine, construction industries and ballistic armor.
First time FRP was introduced in 1980s and after 35 years the construction industries are still using
steel and aluminum in the building. Although FRP is costlier than the steel and other building metals
but the property of FRP makes it a very reliable and useful material which can be used in the building.
According to (Chris BURGOYNE, 2007) the cost of CFRP is about 4.21 times, GFRP is 2.25 times
and AFRP is 4.21 times of steel but it was the rate analysis done in year 2007 now we have so many
industries which manufacture FRP in most of the countries like Japan, china, India etc.
So this paper is all about the cost benefit analysis of a building situated in the corrosive environment
where we can replace contemporary material with FRP
There are three type of FRP materials in the market which are:
1. Carbon Fiber Reinforced Plastic
2. Glass Fiber Reinforced Plastic
3. Aramid Fiber Reinforced Plastic
Fiber Reinforced Polymer (FRP) composites with fibers/fabrics bonded together with the help of
organic polymers (resin system) are being referred to as the materials of 21st century because of
many inherent advantages. Some of the inherent advantages of FRPs over traditional materials are:
(1) Superior thermo-mechanical properties such as high strength and stiffness, and light weight,
(2) Excellent corrosion resistance,
(3) Magnetic transparency,
(4) Design flexibility (tailorability),
(5) Long-term durability under harsh service environments.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 6 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Composites can be three to five times stronger, two to three times stiffer, and three to four times
lighter than metals such as steel and aluminum. In addition, composites are dimensionally stable,
aesthetically pleasing and cost effective with better durability and lower maintenance than the
conventional mateirals. In the United States of America, FRP composites applications to civil
infrastructure started in the form of marine structures, piers, tanks and pilings for military
requirement. Since then, major field implementations of FRP composites have taken place in bridges,
roads, marine structures and retrofitting of structures, with great success in retrofits (Mallick, 1993;
Chakrabarti et al., 2002; CFC-Polymer Composites Conference Proceedings, 2002 and 2007).
In the last decade, significant efforts have been made to develop and implement design guidelines,
construction and maintenance standards, and specifications for FRP rebars, wraps, and shapes (I-
section, WF section, box section, angles etc.) including standardized test methods. Various
researchers and organizations have been contributing to cover a wide variety of applications. Large
volume usage of FRPs in civil infrastructure is drawing increased interest including field evaluation
and development of design and construction specifications. The construction of experimental and
demonstration structures using FRP composites in addition to the recent advances in guide
specifications has revealed the potential increase in structural efficiency and economic viability using
FRP components and systems (See list of references in addition to Appendixes B and C, and ASCE
LRFD draft code for FRP, 2010). In addition to providing a greater understanding on the FRP
composite design, optimization, reliability and manufacturing feasibility, the research and
development efforts have been resulting in extensive field implementations and an opportunity to
collect field data to develop better design and construction guidelines.
Advantages and Disadvantages of FRP
In addition to superior thermo-mechanical properties, FRP composites have many advantages over
conventional materials (Tables 1.1 and 1.2). These advantages are gradually being utilized in the
construction industry for infrastructure applications. Some of the marine and water way applications
such as miter gates will greatly benefit by the use of FRPs in terms of high strength, stiffness,
corrosion resistance, ease of installation, simple repair methods, excellent durability, long service
life, minimum maintenance and lower life cycle costs. Some of the advantages of FRPs are:
.
1. Rapid installation: FRPs can be fast implemented due to modular, pre-fabricated, and light
weight units that eliminate forming and curing efforts necessary for conventional materials such
as concrete decks or elaborate welding and riveting needed in heavy steel construction.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 7 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
2. Light weight: FRP bars are so light weighted as compared to steel which can be transported in
a truck with more number of quantity. A typical 8" FRP deck including wearing surface weighs
25 psf vs. 120 psf for a standard 9.5" concrete deck. Reduction in dead load results in an increased
live load capacity with possible elimination of weight restrictions
3. Reduced interruption: Low down-time of an in-service structure by employing rapid
installation procedures can lead to lower user costs, lower maintenance, higher safety, and better
public relations.
4. Good durability: Excellent resistance to deicing salts and other chemicals results in eliminating
corrosion, cracking, and spalling associated with steel reinforced concrete.
5. Long service life: Large, non-civil FRP structures have performed extremely well in harsh
environments for decades. As an example, FRP bridge decks are expected to provide service life
of about 75-100 years with little maintenance.
6. Fatigue and impact resistance: FRPs have high fatigue endurance and impact resistance.
7. Quality control: Shop fabrication of FRP results in excellent quality control with lower
transportation cost.
8. Ease of installation: FRP structural systems or subsystems such as bridge decks have been used
by general contractors or maintenance crew using standard details with installation time reduction
of up to 80%, thus eliminating traffic congestion and construction site related accident.
9. Cost savings: structural rehabilitation using FRP costs a fraction (1/15th to 1/10th) of the
replacement cost and extends the service life by additional 25-30 years. Rehabilitation also results
in less environmental impact and green house gas emissions (Ryszard, 2010). Similarly, new FRP
construction provides superior FRP thermo-mechanical properties and lower life-cycle costs.
Some of the disadvantages of FRPs are: slightly higher initial costs, limited experience with these
materials by design professionals and contractors, lack of data on long-term field performance, and
absence of full spectrum of codes and specifications similar to conventional materials.
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Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Table 1.1 Merit Comparison and Ratings for FRP and Steel Property (Parameter) Merit/Advantage (Rating) Rating Scale
FRP Steel
Strength/stiffness 4-5 4 1: Very Low
2: Low
3: Medium
4: High
5: Very High
Weight 5 2
Corrosion resistance/
Environmental Durability
4-5 3
Ease of field construction 5 3-4
Ease of repair 4-5 3-5
Fire 3-5 4
Transportation/handling 5 3
Toughness 4 4
Acceptance 2-3 5
Maintenance 5 3
Note: Higher rating indicates better desirability of the property
Table 1.2 FRP Merits and Suitability of Applications Parameter FRP Application
FRP Application
Strength/stiffness Very high aerospace
High marine, construction, pipes, bridges, reinforcing bars, automotive
Weight Very high aerospace, marine, construction, pipes, bridges, reinforcing bars, automotive
Corrosion resistance/
Environmental Durability
Very high marine, boat industry, construction industry, aerospace
High automotive, leisurely applications
Ease of field construction High buildings, bridges, pavements, kiln linings, wind mill blades, radomes
Ease of repair High Bridges, tunnels, underwater piles.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 9 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Fire Very high aerospace, marine, automotive, blast resistant FRP construction.
Medium bridge decks, leisure products, marine boats
Transportation/handling Very high shapes, bridge decks, components and assembled
FRP systems
Toughness and impact High bullet proof vests, vandalism and graffiti proof walls.
Acceptance low construction and aerospace industries
Low offshore and fire resistant applications.
Some of the marine applications with FRP use are discussed in Chapter 3. Suitability of FRP usage for
offshore and marine applications is listed in Table 1.3.
Table 1.3 FRP Use and Suitability for Marine Applications
Marine/ off-shore
Application FRP Suitability
Advantages Examples
Boating/sports related
moisture resistance, ease of use and repair, high strength/ stiffness, light weight, corrosion resistance
boats, seating and storage compartments, fishing rods etc.
Naval applications
high strength/stiffness, light weight, corrosion resistance, ease of navigation, longer service life
ship decks, aircraft landing platforms, cabins, gun housings, walking platforms, rails etc.
Off-shore applications
moisture resistance, ease of use, high strength/stiffness, corrosion resistance, ease of construction, longer service life, minimum maintenance, ease of repair, fire resistance.
piles, retaining walls, pedestrian walkways, bridges, pavement panels for oil fields and off-shore structures, buoys and floats etc.
Hydraulic structures and supporting structural elements
moisture resistance, high strength/stiffness, light weight, corrosion resistance, longer service life, minimum maintenance and ease of construction.
hydraulic gates, pumps, pipes, dampers, grating structures, access structures etc.
FRP is non corrosive material which can be used in the building reinforcement which reduce the
damage caused by the corrosion. In this paper we will discuss the areas where we can use FRP in the
structure and its stability in that member and at last Cost analysis will be done when we use FRP as
a reinforcement material in the building or any other structure.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 10 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
1.2 Need of Study Around the world we are having several upcoming projects near the coast line so the study is
needed to understand the effect on cost when we use FRP in the structure because FRP is a costly
material compare to steel which may or may not increase the structure overall cost.
It will may or may not increase the structure cost because if we use FRP in a structure then we can
avoid the problem that we face in a structure caused due to corrosion which reduce strength of the
structure, foundation loosing plaster from the surface of the reinforced section due to expansion
caused due to rusting as well as in building envelopes.
1.3 Aim The aim of the paper is to give a brief about the FRP Products, There properties and the effect on
cost of a structure if we replace steel with FRP.
1.4 Objectives The objectives of this paper are:-
o To study about FRP Manufacturing and its properties.
o To study about the various applications of FRP.
o To design and analyze a FRP member.
o Finite element analysis of a simple beam using FRP as a reinforcement.
o Role of FRP in the sustainable world.
o To find out the cost benefit of the elements used in a corrosive environment structure which
can be replaced by the FRP.
1.5 Scope of study This study will cover all the forms of FRP that can be used in a building and give a brief about FRP
rebars its properties, design, analysis, uses and the effect on cost of a build during construction as
well as the cost analysis of the structure.
This study will give an idea on the advantage of FRP over steel when we are using FRP in a corrosive
environment like coast line and it will give an initial idea to the designer about the advantage and
disadvantage of FRP over steel
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 11 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
1.6 Methodology • Initially study about the properties of FRP is needed to start the analysis and go through with
the relevant articles/journals, codes available globally.
• Then find out the cost of each element of a building where we can use FRP and to justify that
we can use FRP in the building.
• Analysis of a member where we can use FRP as reinforcement to justify that we can use FRP
as a Reinforcement material.
• The cost analysis for the building by calculating the total quantity and cost of the building
material according to the present market which can be replaced with FRP product to conduct
the cost benefit analysis of FRP
1.7 Seminar Organization
Chapter 1 – Introduction
This chapter describes the intent of this seminar work by describing about the need for the
study, Aim of the work with emphasis on the objective and Scope of the study along with the
methodology used to achieve them.
Chapter 2- Literature Review
This Chapter describes about the available literature on this topic in the form of Books,
Journals, Seminar works, Codes and Standards, Conference proceedings, Published and
unpublished papers etc to establish a theoretical framework for the study topic, define key
terms, definitions and terminology, identify studies, models, case studies etc supporting the
topic and to identify the research gap in available sources.
Chapter 3- Materials Introduction
This chapter gives an introduction of the FRP product, its manufacture process, properties and
the comparison of FRP material with the steel properties, stability, and conductivity etc.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 12 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Chapter 4 – Code Provision
In this chapter the various code used in the design, experiment and analysis is listed.
Chapter 5 – Manual Design Of FRP Beam
In this chapter manual design problem is explained with all the design procedure as per
ACI440.04r and all the tables and equations references are given which are explained in the code.
The design problem is A simply supported, normal weight concrete beam with fc’ = 27.6 MPa is
needed in a facility to support a machine. The beam is an interior beam. The beam is to be
designed to carry a service load of wLL =5.8 kN/m an a superimposed service load od wSDL =3.0
kN/m over a span of l =3.35m.
Chapter 6 – Analysis of Beam Using FEM
This chapter analysis of FRP reinforced beam is analyzed using Finite Element Analysis the
same section that we design in the previous chapter is analyzed and result of that section are
compared to give a relevant theory about its behavior.
Chapter 7 – Costing
This chapter covers costing of the FRP bars and the areas where we can use the FRP product in
the section and the procedure and area where we can save the cost when we are using FRP as
rebar.
Chapter 8- Summery
In this chapter the summer of full report is described
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Study of Material Properties
Applications of FRP Materials
Design of a FRP Member• Manual Design • FEM Analysis of manual design
Costing and Cost analysis of FRP
Summery
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Chapter 2: Literature Review
1. General In this chapter the literature which are used to carry out this study is explained. In this section
we have some main division which are published, unpublished papers, Codes.
2. Codes & Published Papers
2.1 State-of-the-Art Report on Fiber Reinforced Plastic (FRP) Reinforcement for
Concrete Structures (ACI 440.04r, 2002)
In this code the ACI committee broadly explain about the history, property, and supplier of
the FRP in the different countries as well as they explain about some of the projects where they used
FRP in the construction industries.
Fiber Reinforced Plastic (FRP) products were first used to reinforce concrete structures in the mid
1950s (Rubinsky and Rubinsky 1954; Wines et al. 1966). Today, these FRP products take the form
of bars, cables, 2-D and 3-D grids, sheet materials, plates, etc. FRP products may achieve the same
or better reinforcement objective of commonly used metallic products such as steel reinforcing bars,
prestressing tendons, and bonded plates. Application and product development efforts in FRP
composites are widespread to address the many opportunities for reinforcing concrete members
(Nichols 1988). Some of these efforts are:
• High volume production techniques to reduce manufacturing costs
• Modified construction techniques to better utilize the strength properties of FRP and reduce
construction costs
• Optimization of the combination of fiber and resin matrix to ensure optimum compatibility with
Portland cement
• Other initiatives which are detailed in the subsequent
Chapters of this report The common link among all FRP products described in his report is the use
of continuous fibers glass, aramid, carbon, etc.) Embedded in a resin matrix, the glue that allows the
fibers to work together as a single element. Resins used are thermoset (polyester, vinyl ester, etc.) or
thermoplastic (nylon, polyethylene terephthalate, etc.). FRP composites are differentiated from short
fibers used widely today to reinforce nonstructural cementitious products known as fiber reinforced
concrete (FRC). The production methods of bringing continuous fibers together with the resin matrix
allows the FRP material to be tailored such that optimized reinforcement of the concrete structure is
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achieved. The pultrusion process is one such manufacturing method widely practiced today. It is used
to produce consumer and construction products such as fishing rods, bike flags, shovel handles,
structural shapes, etc. The pultrusion process brings together continuous forms of reinforcements and
combines them with a resin to produce high-fiber volume, directionally oriented FRP products. This,
as well as other manufacturing processes used to produce FRP reinforcement for concrete structures,
is explained in more detail later in the report. The concrete industry's primary interest in FRP
reinforcement is in the fact that it does not ordinarily because durability problems such as those
associated with steel reinforcement corrosion. Depending on the constituents of an FRP composite,
other deterioration phenomena can occur as explained in the report. Concrete members can benefit
from the following features of FRP reinforcement: light weight, high specific strength and modulus,
durability, corrosion resistance, chemical and environmental resistance, electromagnetic
permeability, and impact resistance. Numerous FRP products have been and are being developed
worldwide. Japan and Europe are more advanced than the U.S. in this technology and claim a larger
number of completed field applications because their systematic research and development efforts
started earlier and because their construction industry has taken a leading role in development efforts.
2.2 Serviceability of Concrete Beams Prestressed By fiber Reinforced Plastic
Tendons (By Amr. A Abdelrahman1995)
In this paper they shown that CFRP reinforcement can be successfully used for partial prestressing
of concrete beams. The advantages of using this technique to reduce the cost and to increase the
deformability of the structure and they have also done an experimental work to find out the stability
of the FRP as a reinforcement
2.3 Retrofitting of Existing Bridge Using Externally Bonded FRP Composite
Applications and Challenges (MEDIA)
The repair and rehabilitation of aging and deteriorating of concrete bridges and infrastructure poses
an urgent challenge for the civil engineering community. FRPs can play key roles in meeting these
challenges. FRP composite materials show great potential for integration into the bridge
infrastructure. Despite these beneficial superior properties over the other traditional materials,
widespread application of FRP composites to the bridge infrastructure has been slow and uneven.
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With FRP composites, the Western and neighboring countries are already changing the way they
build and maintain their bridges. Although a large research base is already available about these
materials, only a small portion has resulted in actual applications in bridge infrastructure systems in
India.
However, there are several significant, but not insurmountable, challenges to overcome before
widespread implementation occurs. These challenges include a lack of familiarity with the material
among practicing bridge engineers, the cost of the material, and the lack of a unified effort (especially
from a widely accepted coordinating agency) to move implementation efforts forward. Practicing
civil engineers and even most newly graduated civil engineers typically have very little knowledge
of FRP composite materials. If successful widespread application is to occur, these engineers are the
ones who will apply FRP composite materials to the infrastructure. With the removal of certain
obstacles to implementation, FRP composite materials have a place in the bridge infrastructure.
Quality control is crucial to the successful application of FRP systems. Most FRP strengthening
systems are simple to install. However, improper installation (e.g., not properly mixing epoxy
components or saturating the fibers, misaligning the fibers, etc.) could be avoided with careful
attention.
Even though FRP component costs are higher than traditional materials on a square foot basis,
they may be competitive in terms of lifecycle costs. FRP composite materials may be the most cost-
effective solution for repair, rehabilitation, and construction of portions of the bridge infrastructure
if used intelligently.
2.4 The role of FRP composites in a sustainable world (Jain, 2009) The ideal sustainable structure and material would have a closed life cycle where renewable
resources, energy, and zero waste, along with minimal impact on environment and society, are
considered. Certainly, there are few materials that could qualify as ideal sustainable materials and
still satisfy all the performance requirements of structural systems. Even more challenging are the
demands of sustainable design which essentially seeks to achieve tailored design, construction, and
maintenance plans depending on impact priorities, regional issues, and economic requirements.
In the case of FRP composites, environmental concerns appear to be a barrier to its feasibility as a
sustainable material especially when considering fossil fuel depletion, air pollution, smog, and
acidification associated with its production. In addition, the ability to recycle FRP composites is
limited and, unlike steel and timber, structural components cannot easily be reused to perform a
similar function in another structure. On the other hand, FRP composites’ potential benefits, as
described in the paper, may potentially mitigate some environmental impacts
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2.5 Bridge decks of fibre reinforced polymer (FRP): A sustainable solution (Valbona Mara, 2013)
Fibre reinforced polymer (FRP) bridge decks have become an interesting alternative and they have
attracted increasing attention for applications in the refurbishment of existing bridges and the
construction of new bridges. The benefits brought by lightweight, high-strength FRP materials to
these applications are well recognized. However, the sustainability of bridge concepts incorporating
FRP decks still needs to be demonstrated and verified. The aim of this paper is to bridge this
knowledge gap by examining the sustainability of these FRP solutions in comparison with traditional
bridge concepts. An existing composite (steel–concrete) bridge with a concrete deck that had
deteriorated was selected for this purpose. Two scenarios are studied and analyzed the total
replacement of the entire bridge superstructure and the replacement of the concrete deck with a new
deck made of GFRP. The analyses prove that FRP decks contribute to potential cost savings over the
life cycle of bridges and a reduced environmental impact.
2.6 Guide for the Design and Construction of Externally Bonded FRP Systems for
Strengthening Concrete Structures (440, Guide for the Design and Construction of
Externally Bonded FRP Systems for Strengthening Concrete Structures, 2008)
The strengthening or retrofitting of existing concrete structures to resist higher design loads, correct
strength loss due to deterioration, correct design or construction deficiencies, or increase ductility
has traditionally been accomplished using conventional materials and construction techniq ues.
Externally bonded steel plates, steel or concrete jackets, and external post-tensioning are just some
of the many traditional techniques available.
Composite materials made of fibers in a polymeric resin, also known as fiber-reinforced polymers
(FRPs), have emerged as an alternative to traditional materials for repair and rehabilitation. For the
purposes of this document, an FRP system is defined as the fibers and resins used to create the
composite laminate, all applicable resins used to bond it to the concrete substrate, and all applied
coatings used to protect the constituent materials. Coatings used exclusively for aesthetic reasons are
not considered part of an FRP system.
FRP materials are lightweight, noncorrosive, and exhibit high tensile strength. These materials are
readily available in several forms, ranging from factory-made laminates to dry fiber sheets that can
be wrapped to conform to the geometry of a structure before adding the polymer resin. The relatively
thin profiles of cured FRP systems are often desirable in applications where aesthetics or access is a
concern.
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The growing interest in FRP systems for strengthening and retrofitting can be attributed to many
factors. Although the fibers and resins used in FRP systems are relatively expensive compared with
traditional strengthening materials such as concrete and steel, labor and equipment costs to install
FRP systems are often lower (Nanni 1999). FRP systems can also be used in areas with limited access
where traditional techniques would be difficult to implement.
The basis for this document is the knowledge gained from a comprehensive review of experimental
research, analytical work, and field applications of FRP strengthening systems. Areas where further
research is needed are highlighted in this document.
2.7 Guide for the Design and Construction of Structural Concrete Reinforced with FRP
Bars (ACI 440, 2006) This document provides recommendations for the design and construction of FRP reinforced
concrete structures. The document only addresses non prestressed FRP reinforcement (concrete
structures prestressed with FRP tendons are covered in ACI 440.4R). The basis for this document is
the knowledge gained from worldwide experimental research, analytical research work, and field
applications of FRP
Reinforcement. The recommendations in this document are intended to be conservative. Design
recommendations are based on the current knowledge and intended to supplement existing codes and
guidelines for conventionally reinforced concrete structures and to provide engineers and building
officials with assistance in the specification, design, and construction of structural concrete
reinforced with FRP bars. ACI 440.3R provides a comprehensive list of test methods and material
specifications to support design and construction guidelines. The use of FRP reinforcement in
combination with steel reinforcement for structural concrete is not addressed in this document.
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Chapter : 3 Materials Introduction (FRP)
Fibre Reinforced Plastic (FRP) is a composite material made of a polymer matrix reinforced with
fibres. The fibres are usually glass, carbon, aramid, or basalt. Rarely other fibres such as paper or
wood or asbestos have been used. The polymer is usually made up of some organic compound like
an epoxy vinylester or polyester thermosetting plastic and phenol formaldehyde resins are still in use.
There are three type of Fibe Reinforced Plastic:-
• Carbon Fibe Reinforced Plastic
• Glass Fibe Reinforced Plastic
• Aramid Fibe Reinforced Plastic
FRPs are commonly used in the aerospace, automotive, marine, construction industries and ballistic
armor.
3.1 History
Bakelite was the first fibre-reinforced plastic. Dr. Baekeland had originally set out to find a
replacement for shellac (made from the excretion of lac beetles). Chemists had begun to recognize
that many natural resins and fibres were polymers, and Baekeland investigated the reactions of phenol
and formaldehyde. He first produced a soluble phenol-formaldehyde shellac called "Novolak" that
never became a market success, then turned to developing a binder for asbestos which, at that time,
was moulded with rubber. By controlling the pressure and temperature applied
to phenol and formaldehyde, he found in 1905 he could produce his dreamed-of hard mouldable
material (the world's first synthetic plastic): bakelite (Amato, 1999) (Baekeland, 2000)He announced
his invention at a meeting of the American Chemical Society on February 5, 1909 (New Chemical
Substance, 1909).
The development of fibre-reinforced plastic for commercial use was being extensively researched in
the 1930s. In the UK, considerable research was undertaken by pioneers such as Norman de Bruyne.
It was particularly of interest to the aviation industry. (Synthetic Resin – Use in Aircraft Construction,
1936)
Mass production of glass strands was discovered in 1932 when Games Slayter, a researcher at Owens-
Illinois accidentally directed a jet of compressed air at a stream of molten glass and produced fibres.
A patent for this method of producing glass wool was first applied for in 1933 (US Patent Number
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2133235: Method & Apparatus for Making Glass Wool, 1933). Owens joined with the Corning
company in 1935 and the method was adapted by Owens Corning to produce its patented "fibreglas"
(one "s") in 1936. Originally, fiberglass was a glass wool with fibres entrapping a great deal of gas,
making it useful as an insulator, especially at high temperatures.
A suitable resin for combining the "fiberglass" with a plastic to produce a composite material, was
developed in 1936 by du Pont. The first ancestor of modern polyester resins is Cyanamid's resin of
1942. Peroxide curing systems were used by then. (50 years of reinforced plastic boats, 2660) With
the combination of Fiberglas and resin the gas content of the material was replaced by plastic. This
reduced to insulation properties to values typical of the plastic, but now for the first time the
composite showed great strength and promise as a structural and building material. Confusingly,
many glass fiber composites continued to be called "fiberglass" (as a generic name) and the name
was also used for the low-density glass wool product containing gas instead of plastic.
Ray Greene of Owens Corning is credited with producing the first composite boat in 1937, but did
not proceed further at the time due to the brittle nature of the plastic used. In 1939 Russia was reported
to have constructed a passenger boat of plastic materials, and the United States a fuselage and wings
of an aircraft. (Notable Progress – the use of plastics, Evening Post, Wellington, New Zealand,
Volume CXXVIII, Issue 31, 1939) The first car to have a fibre-glass body was the 1946 Stout Scarab.
Only one of this model was built. ( Car of the future in plastics, The Mercury (Hobart, Tasmania),
1946)
The first fibre-reinforced plastic plane fuselage was used on a modified Vultee BT-13A designated
the XBT-16 based at Wright Field in late 1942 (American Warplanes of World War II, David Donald,
Aerospace Publishing Limited, 1995). In 1943 further experiments were undertaken building
structural aircraft parts from composite materials resulting in the first plane, a Vultee BT-15, with a
GFRP fuselage, designated the XBT-19, being flown in 1944. (Conrardy, 1971) (Moulded glass fibre
Sandwich Fuselages for BT-15 Airplane, Army Air Force Technical Report 5159,, 1944)
(Placeholder1) (Reinforced plastics handbook, 2004)A significant development in the tooling for
GFRP components had been made by Republic Aviation Corporation in 1943 (Tim Palucka and
Bernadette Bensaude-Vincent, n.d.) .
Carbon fibre production began in the late 1950s and was used, though not widely, in British industry
beginning in the early 1960s. Aramid fibres were being produced around this time also, appearing
first under the trade name Nomex by DuPont. Today, each of these fibres is used widely in industry
for any applications that require plastics with specific strength or elastic qualities. Glass fibres are
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the most common across all industries, although carbon-fibre and carbon-fibre-aramid composites
are widely found in aerospace, automotive and sporting good applications (Erhard). These three
(glass, carbon, and aramid) continue to be the important categories of fibre used in FRP.
Global polymer production on the scale present today began in the mid 20th century, when low
material and productions costs, new production technologies and new product categories combined
to make polymer production economical. The industry finally matured in the late 1970s when world
polymer production surpassed that of Steel, making polymers the ubiquitous material that it is today.
Fibre-reinforced plastics have been a significant aspect of this industry from the beginning.
3.2 Manufacture Process 3.2.1 General
A polymer is generally manufactured by Step-growth polymerization or addition
polymerization. When combined with various agents to enhance or in any way alter the material
properties of polymers the result is referred to as a plastic. Composite plastics refer to those types of
plastics that result from bonding two or more homogeneous materials with different material
properties to derive a final product with certain desired material and mechanical properties. Fibre-
reinforced plastics are a category of composite plastics that specifically use fibre materials to
mechanically enhance the strength and elasticity of plastics. The original plastic material without
fibre reinforcement is known as the matrix. The matrix is a tough but relatively weak plastic that is
reinforced by stronger stiffer reinforcing filaments or fibres. The extent that strength and elasticity
are enhanced in a fibre-reinforced plastic depends on the mechanical properties of both the fibre and
matrix, their volume relative to one another, and the fibre length and orientation within the matrix
(Smallman). Reinforcement of the matrix occurs by definition when the FRP material exhibits
increased strength or elasticity relative to the strength and elasticity of the matrix alone (Erhard).
Figure 1 Formation Process Of FRP
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3.2.2 Manufacturing Process
FRP involves two distinct processes, the first is the process whereby the fibrous material is
manufactured and formed, the second is the process whereby fibrous materials are bonded with the
matrix during moulding. (Erhard). Chemical Structure is shown in fig. 2
Figure 2 Structure of FRP
3.2.3 Fibre
Reinforcing Fibre is manufactured in both two-dimensional and three-dimensional orientations
1. Two Dimensional Fibre-Reinforced Polymer are characterized by a laminated structure in
which the fibres are only aligned along the plane in x-direction and y-direction of the
material. This means that no fibres are aligned in the through thickness or the z-direction,
this lack of alignment in the through thickness can create a disadvantage in cost and
processing. Costs and labour increase because conventional processing techniques used to
fabricate composites, such as wet hand lay-up, autoclave and resin transfer moulding, require
a high amount of skilled labor to cut, stack and consolidate into a preformed component.
Phenol Formaldehyde
Vinyl Ester
Epoxy
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2. Three-dimensional Fibre-Reinforced Polymer composites are materials with three
dimensional fibre structures that incorporate fibres in the x-direction, y-direction and z-
direction. The development of three-dimensional orientations arose from industry's need to
reduce fabrication costs, to increase through-thickness mechanical properties, and to improve
impact damage tolerance; all were problems associated with two dimensional fibre-
reinforced polymers.
The manufacture of fibre preforms
Fibre preforms are how the fibres are manufactured before being bonded to the matrix. Fibre preforms
are often manufactured in sheets, continuous mats, or as continuous filaments for spray applications.
The four major ways to manufacture the fibre preform is through the textile processing techniques
of Weaving, knitting, braiding and stitching.
1. Weaving can be done in a conventional manner to produce two-dimensional fibres as well in
a multilayer weaving that can create three-dimensional fibres. However, multilayer weaving
is required to have multiple layers of warp yarns to create fibres in the z- direction creating
a few disadvantages in manufacturing, namely the time to set up all the warp yarns on
the loom. Therefore most multilayer weaving is currently used to produce relatively narrow
width products, or high value products where the cost of the preform production is
acceptable. Another one of the main problems facing the use of multilayer woven fabrics is
the difficulty in producing a fabric that contains fibres oriented with angles other than 0" and
90" to each other respectively.
2. The second major way of manufacturing fibre preforms is Braiding. Braiding is suited to the
manufacture of narrow width flat or tubular fabric and is not as capable as weaving in the
production of large volumes of wide fabrics. Braiding is done over top of mandrels that vary
in cross-sectional shape or dimension along their length. Braiding is limited to objects about
a brick in size. Unlike standard weaving, braiding can produce fabric that contains fibres at
45 degrees angles to one another. Braiding three-dimensional fibres can be done using four
step, two-step or Multilayer Interlock Braiding. Four step or row and column braiding utilizes
a flatbed containing rows and columns of yarn carriers that form the shape of the desired
preform. Additional carriers are added to the outside of the array, the precise location and
quantity of which depends upon the exact preform shape and structure required. There are
four separate sequences of row and column motion, which act to interlock the yarns and
produce the braided preform. The yarns are mechanically forced into the structure between
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each step to consolidate the structure in a similar process to the use of a reed in weaving.
Two-step braiding is unlike the four-step process because the two-step includes a large
number of yarns fixed in the axial direction and a fewer number of braiding yarns. The
process consists of two steps in which the braiding carriers move completely through the
structure between the axial carriers. This relatively simple sequence of motions is capable of
forming preforms of essentially any shape, including circular and hollow shapes. Unlike the
four-step process, the two-step process does not require mechanical compaction the motions
involved in the process allows the braid to be pulled tight by yarn tension alone. The last type
of braiding is multi-layer interlocking braiding that consists of a number of standard circular
braiders being joined together to form a cylindrical braiding frame. This frame has a number
of parallel braiding tracks around the circumference of the cylinder but the mechanism allows
the transfer of yarn carriers between adjacent tracks forming a multilayer braided fabric with
yarns interlocking to adjacent layers. The multilayer interlock braid differs from both the
four step and two-step braids in that the interlocking yarns are primarily in the plane of the
structure and thus do not significantly reduce the in-plane properties of the preform. The
four-step and two-step processes produce a greater degree of interlinking as the braiding
yarns travel through the thickness of the preform, but therefore contribute less to the in-plane
performance of the preform. A disadvantage of the multilayer interlock equipment is that due
to the conventional sinusoidal movement of the yarn carriers to form the preform, the
equipment is not able to have the density of yarn carriers that is possible with the two step
and four step machines.
3. Knitting fibre preforms can be done with the traditional methods of Warp and [Weft] Knitting,
and the fabric produced is often regarded by many as two-dimensional fabric, but machines
with two or more needle beds are capable of producing multilayer fabrics with yams that
traverse between the layers. Developments in electronic controls for needle selection and knit
loop transfer, and in the sophisticated mechanisms that allow specific areas of the fabric to
be held and their movement controlled. This has allowed the fabric to form itself into the
required three-dimensional preform shape with a minimum of material wastage.
4. Stitching is arguably the simplest of the four main textile manufacturing techniques and one
that can be performed with the smallest investment in specialized machinery. Basically
stitching consists of inserting a needle, carrying the stitch thread, through a stack of fabric
layers to form a 3D structure. The advantages of stitching are that it is possible to stitch both
dry and prepreg fabric, although the tackiness of the prepreg makes the process difficult and
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generally creates more damage within the prepreg material than in the dry fabric. Stitching
also utilizes the standard two-dimensional fabrics that are commonly in use within the
composite industry therefore there is a sense of familiarity concerning the material systems.
The use of standard fabric also allows a greater degree of flexibility in the fabric lay-up of
the component than is possible with the other textile processes, which have restrictions on
the fibre orientations that can be produced (Tong, 2002)
3.2.4 Forming processes
A rigid structure is usually used to establish the shape of FRP components. Parts can be laid up on a
flat surface referred to as a "caul plate" or on a cylindrical structure referred to as a "mandrel".
However most fibre-reinforced plastic parts are created with a mold or "tool." Molds can be concave
female molds, male molds, or the mold can completely enclose the part with a top and bottom mold.
The moulding processes of FRP plastics begins by placing the fibre preform on or in the mold. The
fibre preform can be dry fibre, or fibre that already contains a measured amount of resin called
"prepreg". Dry fibres are "wetted" with resin either by hand or the resin is injected into a closed mold.
The part is then cured, leaving the matrix and fibres in the shape created by the mold. Heat and/or
pressure are sometimes used to cure the resin and improve the quality of the final part. The different
methods of forming are listed below.
3.2.4.1 Bladder moulding
Individual sheets of prepreg material are laid up and placed in a female-style mould along with a
balloon-like bladder. The mould is closed and placed in a heated press. Finally, the bladder is
pressurized forcing the layers of material against the mould walls.
3.2.4.2 Compression moulding
When the raw material (plastic block,rubber block, plastic sheet, or granules) contains reinforcing
fibres, a compression molded part qualifies as a fibre-reinforced plastic. More typically the plastic
preform used in compression molding does not contain reinforcing fibres. In compression molding,
A "preform" or "charge", of SMC, BMC is placed into mould cavity. The mould is closed and the
material is formed & cured inside by pressure and heat. Compression moulding offers excellent
detailing for geometric shapes ranging from pattern and relief detailing to complex curves and
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creative forms, to precision engineering all within a maximum curing time of 20 minutes (Composite
moulding , 2004).
3.2.4.3 Autoclave / vacuum bag
Individual sheets of prepreg material are laid-up and placed in an open mold. The material is covered
with release film, bleeder/breather material and a vacuum bag. A vacuum is pulled on part and the
entire mould is placed into an autoclave (heated pressure vessel). The part is cured with a continuous
vacuum to extract entrapped gasses from laminate.
This is a very common process in the aerospace industry because it affords precise control over
moulding due to a long, slow cure cycle that is anywhere from one to several hours (Dogan, Donchev,
& Bhonge, 2012).
This precise control creates the exact laminate geometric forms needed to ensure strength and safety
in the aerospace industry, but it is also slow and labour-intensive, meaning costs often confine it to
the aerospace industry (Composite moulding , 2004).
3.2.4.4 Mandrel wrapping
Sheets of prepreg material are wrapped around a steel or aluminium mandrel. The prepreg material
is compacted by nylon or polypropylene cello tape. Parts are typically batch cured by vacuum
bagging and hanging in an oven. After cure the cello and mandrel are removed leaving a hollow
carbon tube. This process creates strong and robust hollow carbon tubes.
3.2.4.5 Wet layup
Wet layup forming combines fibre reinforcement and the matrix as they are placed on the forming
tool (Erhard).]Reinforcing Fibre layers are placed in an open mould and then saturated with a wet
[resin] by pouring it over the fabric and working it into the fabric. The mould is then left so that the
resin will cure, usually at room temperature, though heat is sometimes used to ensure a proper cure.
Sometimes a vacuum bag is used to compress a wet layup. Glass fibres are most commonly used for
this process, the results are widely known as fibreglass, and is used to make common products like
skis, canoes, kayaks and surf boards (Composite moulding , 2004).
3.2.4.6 Chopper gun
Continuous strands of fibreglass are pushed through a hand-held gun that both chops the strands and
combines them with a catalysed resin such as polyester. The impregnated chopped glass is shot onto
the mould surface in whatever thickness the design and human operator think is appropriate. This
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process is good for large production runs at economical cost, but produces geometric shapes with
less strength than other moulding processes and has poor dimensional tolerance (Composite
moulding , 2004).
3.2.4.7 Filament winding
Machines pull fibre bundles through a wet bath of resin and wound over a rotating steel mandrel in
specific orientations Parts are cured either room temperature or elevated temperatures. Mandrel is
extracted, leaving a final geometric shape but can be left in some cases (Composite moulding , 2004).
3.2.4.8 Pultrusion
Fibre bundles and slit fabrics are pulled through a wet bath of resin and formed into the rough part
shape. Saturated material is extruded from a heated closed die curing while being continuously pulled
through die. Some of the end products of pultrusion are structural shapes, i.e. I beam, angle, channel
and flat sheet. These materials can be used to create all sorts of fibreglass structures such as ladders,
platforms, handrail systems tank, pipe and pump supports (Composite moulding , 2004).
3.2.4.9 Resin transfer molding
Also called resin infusion. Fabrics are placed into a mould which wet resin is then injected into.
Resin is typically pressurized and forced into a cavity which is under vacuum in resin transfer
molding. Resin is entirely pulled into cavity under vacuum in vacuum-assisted resin transfer molding.
This moulding process allows precise tolerances and detailed shaping but can sometimes fail to fully
saturate the fabric leading to weak spots in the final shape (Composite moulding , 2004).
3.3 Advantages and limitations
FRP allows the alignment of the glass fibres of thermoplastics to suit specific design programs.
Specifying the orientation of reinforcing fibres can increase the strength and resistance to
deformation of the polymer. Glass reinforced polymers are strongest and most resistive to deforming
forces when the polymers fibres are parallel to the force being exerted, and are weakest when the
fibres are perpendicular. Thus this ability is at once both an advantage and a limitation depending on
the context of use.
Weak spots of perpendicular fibres can be used for natural hinges and connections, but can also lead
to material failure when production processes fail to properly orient the fibres parallel to expected
forces. When forces are exerted perpendicular to the orientation of fibres the strength and elasticity
of the polymer is less than the matrix alone. In cast resin components made of glass reinforced
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polymers such as UP and EP, the orientation of fibres can be oriented in two-dimensional and three-
dimensional weaves.
This means that when forces are possibly perpendicular to one orientation, they are parallel to
another orientation; this eliminates the potential for weak spots in the polymer.
3.4 Failure Mode
Structural failure can occur in FRP materials when:
• Tensile forces stretch the matrix more than the fibres, causing the material to shear at the interface
between matrix and fibres.
• Tensile forces near the end of the fibres exceed the tolerances of the matrix, separating the fibres
from the matrix.
• Tensile forces can also exceed the tolerances of the fibres causing the fibres themselves to
fracture leading to material failure (Erhard).
3.5 Material Requirements
The matrix must also meet certain requirements in order to first be suitable for FRPs and ensure a
successful reinforcement of itself. The matrix must be able to properly saturate, and bond with the
fibres within a suitable curing period. The matrix should preferably bond chemically with the fibre
reinforcement for maximum adhesion. The matrix must also completely envelop the fibres to protect
them from cuts and notches that would reduce their strength, and to transfer forces to the fibres. The
fibres must also be kept separate from each other so that if failure occurs it is localized as much as
possible, and if failure occurs the matrix must also debond from the fibre for similar reasons. Finally
the matrix should be of a plastic that remains chemically and physically stable during and after the
reinforcement and moulding processes. To be suitable as reinforcement material, fibre additives must
increase the tensile strength and modulus of elasticity of the matrix and meet the following
conditions; fibres must exceed critical fibre content; the strength and rigidity of fibres itself must
exceed the strength and rigidity of the matrix alone; and there must be optimum bonding between
fibres and matrix.
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• Glass fibre material
"Fiberglass reinforced plastics" or FRPs (commonly referred to simply as fiberglass) use textile
grade glass fibres. These textile fibres are different from other forms of glass fibres used to
deliberately trap air, for insulating applications (see glass wool). Textile glass fibres begin as varying
combinations of SiO2, Al2O3, B2O3, CaO, or MgO in powder form. These mixtures are then heated
through direct melting to temperatures around 1300 degrees Celsius, after which dies are used to
extrude filaments of glass fibre in diameter ranging from 9 to 17 µm. These filaments are then wound
into larger threads and spun onto bobbins for transportation and further processing. Glass fibre is by
far the most popular means to reinforce plastic and thus enjoys a wealth of production processes,
some of which are applicable to aramid and carbon fibres as well owing to their shared fibrous
qualities.
Roving is a process where filaments are spun into larger diameter threads. These threads are then
commonly used for woven reinforcing glass fabrics and mats, and in spray applications.
Fibre fabrics are web-form fabric reinforcing material that has both warp and weft directions. Fibre
mats are web-form non-woven mats of glass fibres. Mats are manufactured in cut dimensions with
chopped fibres, or in continuous mats using continuous fibres. Chopped fibre glass is used in
processes where lengths of glass threads are cut between 3 and 26 mm, threads are then used in
plastics most commonly intended for moulding processes. Glass fibre short strands are short 0.2–
0.3 mm strands of glass fibres that are used to reinforce thermoplastics most commonly for injection
moulding.
• Carbon fiber
Carbon fibres are created when polyacrylonitrile fibres (PAN), Pitch resins, or Rayon are carbonized
(through oxidation and thermal pyrolysis) at high temperatures. Through further processes of
graphitizing or stretching the fibres strength or elasticity can be enhanced respectively. Carbon fibres
are manufactured in diameters analogous to glass fibres with diameters ranging from 9 to 17 µm.
These fibres wound into larger threads for transportation and further production processes
(Erhard). Further production processes include weaving or braiding into carbon fabrics, cloths and
mats analogous to those described for glass that can then be used in actual reinforcements
(Smallman).
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• Aramid fiber material
Aramid fibres are most commonly known as Kevlar, Nomex and Technora. Aramids are generally
prepared by the reaction between an amine group and a carboxylic acid halide group (aramid)
(Smallman) commonly this occurs when an aromatic polyamide is spun from a liquid concentration
of sulphuric acid into a crystallized fibre (Erhard). Fibres are then spun into larger threads in order
to weave into large ropes or woven fabrics (Aramid) (Smallman). Aramid fibres are manufactured
with varying grades to based on varying qualities for strength and rigidity, so that the material can
be somewhat tailored to specific design needs concerns, such as cutting the tough material during
manufacture (Erhard).
Examples of polymers best suited for the process
Reinforcing Material Most Common Matrix
Materials
Properties Improved
Glass Fibres UP, EP, PA, PC, POM, PP,
PBT, VE
Strength, Elasticity, heat
resistance
Wood Fibres PE, PP, ABS, HDPE, PLA Flexural strength, Tensile
modulus, Tensile Strength
Carbon and Aramid Fibres EP, UP, VE, PA Elasticity, Tensile Strength,
compression strength,
electrical strength.
Inorganic Particulates Semicrystalline
Thermoplastics, UP
Isotropic shrinkage, abrasion,
compression strength
3.6 Material Property
FRP is a composite material so the property of FRP will be very different which are covered below
3.6.1 Corrosion Resistance
FRP/Composites do not rust, corrode or rot, and they resist attack from most industrial and
household chemicals. This quality has been responsible for applications in corrosive environments
such as those found in the chemical processing and water treatment industries. Resistance to
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corrosion provides long life and low maintenance in marine applications from sailboats and
minesweepers to seawalls and offshore oil platforms.
3.6.2 High Strength, Lightweight
FRP/Composites provide high strength to weight ratios exceeding those of aluminum or steel.
High strength, lightweight FRP/Composites are a rational choice whenever weight savings are
desired, such as components for the transportation industry.
3.6.3 Dimensional Stability
FRP/Composites have high dimensional stability under varying physical, environmental, and
thermal stresses. This is one of the most useful properties of FRP/Composites.
3.6.4 Parts Consolidation and Tooling Minimization.
A single FRP composite molding often replaces an assembly of several metal parts and
associated fasteners, reducing assembly and handling time, simplifying inventory, and reducing
manufacturing costs. A single FRP/Composite tool can replace several progressive tools required in
metal stamping.
3.6.5 High Dielectric Strength and Low Moisture Absorption
The excellent electrical insulating properties and low moisture absorption of FRP/Composites
qualify them for use in primary support applications such as circuit breaker housings, and where low
moisture absorption is required.
3.6.6 Minimum Finishing Required
FRP/Composites can be pigmented as part of the mixing operation or coated as part of the
molding process, often eliminating the need for painting. This is particularly cost effective for large
components such as tub/shower units. Also, on critical appearance components, a class “A” surface
is achieved.
3.6.7 Low to Moderate Tooling Costs
Regardless of the molding method selected, tooling for FRP/Composites usually represents a
small part of the product cost. For either large-volume mass-production or limited runs, tooling cost
is normally substantially lower than that of the multiple forming tools required to produce a similar
finished part in metal.
3.6.8 Design Flexibility
No other major material system offers the design flexibility of FRP/Composites. Present
applications vary widely. They range from commercial fishing boat hulls and decks to truck fenders,
from parabolic TV antennas to transit seating, and from outdoor lamp housings to seed hoppers. What
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the future holds depends on the imagination of today’s design engineers as they develop even more
innovative applications for FRP/Composites.
3.6.9 Thermal conductivity
Good insulator with low thermal conductivity. Thermal conductivity 4 (BTU in. /(hr ft2 °F)
Low thermal coefficient of expansion 7 - 8 (in./in./°F) 10-6 . Where steel have Thermal conductivity
260-460 (BTU/sf/hr/°F/in.) Thermal coefficient of expansion 6 - 8 (in./in./°F) 10-6
3.6.10 EMI /RFI Transparency
Not like steel but FRP is Transparent to radio waves and EMI/RFI transmissions.
3.6.11 Physical properties
• Density—FRP bars have a density ranging from 77.8 to 131.3 lb/ft3 (1.25 to 2.1 g/cm3), one-
sixth to one-fourth that of steel (Table 3.1). Reduced weight lowers transportation costs and may
ease handling of the bars on the project site.
Table 3.1—Typical densities of reinforcing bars, lb/ft3 (g/cm3)
Steel GFRP CFRP AFRP 493.00
(7.90)
77.8 to 131.00
(1.25 to 2.10)
93.3 to 100.00
(1.50 to 1.60)
77.80 to 88.10
(1.25 to 1.40)
• Coefficient of thermal expansion—The coefficients of thermal expansion of FRP bars vary
in the longitudinal and transverse directions depending on the types of fiber, resin, and volume
fraction of fiber. The longitudinal coefficient of thermal expansion is dominated by the properties
of the fibers, while the transverse coefficient is dominated by the resin (Bank 1993). Table 3.2 lists the
longitudinal and transverse coefficients of thermal expansion for typical FRP and steel bars. Note that a
negative coefficient of thermal expansion indicates that the material contracts with increased
temperature and expands with decreased temperature. For reference, concrete has a coefficient of
thermal expansion that varies from 4 × 10–6 to 6 × 10–6/°F (7.2 × 10–6 to 10.8 × 10–6/°C) and is
usually assumed to be isotropic (Mindessetal. 2003).
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Table 3.2—Typical coefficients of thermal expansion for reinforcing bars*
Direction CTE, × 10–6/°F (× 10–6/°C)
Steel GFRP CFRP AFRP
Longitudinal, αL 6.5 (11.7) 3.3 to 5.6
(6.0 to 10.0)
–4.0 to 0.0
(–9.0 to 0.0)
–3.3 to –1.1
(–6 to –2)
Transverse, αT 6.5 (11.7) 11.7 to 12.8
(21.0 to 23.0)
41 to 58
(74.0 to 104.0)
33.3 to 44.4
(60.0 to 80.0) *Typical values for fiber volume fraction ranging from 0.5 to 0.7.
3.6.12 Mechanical properties and behavior
• Tensile behavior— When loaded in tension, FRP bars do not exhibit any plastic behavior
(yielding) before rupture. The tensile behavior of FRP bars consisting of one type of fiber material
is characterized by a linearly elastic stress-strain relationship until failure. The tensile properties of
some commonly used FRP bars are summarized in Table 3.3. The tensile strength and stiffness of an FRP
bar are dependent on several factors. Because the fibers in an FRP bar are the main load-carrying
constituent, the ratio of the volume of fiber to the overall volume of the FRP (fiber-volume fraction)
significantly affects the tensile properties of an FRP bar. Strength and stiffness variations will
occur in bars with various fiber-volume fractions, even in bars with the same diameter, appearance,
and constituents.
The rate of curing, the manufacturing process, and the manufacturing quality control also affect the
mechanical characteristics of the bar (Wu 1990). Unlike steel, the unit tensile strength of an FRP bar
can vary with diameter. For example, GFRP bars from three different manufacturers show tensile
strength reductions of up to 40% as the diameter increases proportionally from 0.375 to 0.875 in.
(9.5 to 22.2 mm) (Faza and GangaRao1993b). On the other hand, similar cross section changes do
not seem to affect the strength of twisted CFRP strands (Santoh 1993). The sensitivity of AFRP bars
to cross section size has been shown to vary from one commercial product to rupture strain, εfu (εfu=
εu,ave – 3σ) and a specified tensileanother.
For example, in braided AFRP bars, there is a lessthan 2% strength reduction as bars increase in
diameter from 0.28 to 0.58 in. (7.3 to 14.7 mm) (Tamura 1993). The strength reduction in a
unidirectionally pultruded AFRP bar with added aramid fiber surface wraps is approximately 7% for
diameters increasing from 0.12 to 0.32 in. (3 to 8 mm) (Noritake et al. 1993).
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The FRP bar manufacturer should be contacted for particular strength values of differently sized
FRP bars.
Table 3.3—Usual tensile properties of reinforcing bars
Steel GFRP CFRP AFRP Nominal yield
stress, ksi (MPa)
40 to 75 (276 to
517) N/A N/A N/A
Tensile strength,
ksi (MPa)
70 to 100 (483 to
690)
70 to 230 (483 to
1600)
87 to 535 (600 to
3690)
250 to 368 (1720 to
2540)
Elastic modulus,
×103 ksi (GPa)
29.0 (200.0)
5.1 to 7.4 (35.0 to
51.0) 15.9 to 84.0 (120.0
to 580.0)
6.0 to 18.2 (41.0 to
125.0)
Yield strain, % 0.14 to 0.25 N/A N/A N/A
Rupture strain,
% 6.0 to 12.0 1.2 to 3.1 0.5 to 1.7 1.9 to 4.4
*Typical values for fiber volume fractions ranging from 0.5 to 0.7.
Determination of FRP bar strength by testing is complicated because stress concentrations in and
around anchorage points on the test specimen can lead to premature failure. An adequate testing grip
should allow failure to occur in the middle of the test specimen. Proposed test methods for
determining the tensile strength and stiffness of FRP bars are available in ACI 440.3R.
The tensile properties of a particular FRP bar should be obtained from the bar manufacturer. Usually,
a normal (Gaussian) distribution is assumed to represent the strength of a population of bar specimens
(Kocaoz et al. 2005). Manufacturers should report a guaranteed tensile strength f * , defined by
this guide as the mean tensile strength of a sample of test specimens minus three times the standard
deviation (f * = f – 3σ), and similarly report a guaranteed modulus, Ef (Ef = Ef,ave).
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Figure 3 Stress Strain Curve Fro FRP
These gu a r a n t e ed values of strength and strain provide a 99.87% probability that the
indicated values are exceeded by similar FRP bars, provided that at least 25 specimens are tested
(Dally and Riley 1991; Mutsuyoshietal. 1990). If fewer specimens are tested or a different
distribution is used, texts and manuals on statistical analysis should be consulted to determine the
confidence level of the distribution parameters (MIL-17 1999). In any case, the manufacturer should
provide a description of the method used to obtain the reported tensile properties.
An FRP bar cannot be bent once it has been manufactured (an exception to this would be an FRP
bar with a thermo- plastic resin that could be reshaped with the addition of heat and pressure). FRP
bars, however, can be fabricated with bends. In FRP bars produced with bends, a strength reduction
of 40 to 50% compared with the tensile strength of a straight bar can occur in the bend portion due
to fiber bending and stress concentrations (Nanni et al. 1998).
• Compressive behavior—While it is not recommended to rely on FRP bars to resist
compressive stresses, the following section is presented to fully characterize the behavior of FRP
bars.
Tests on FRP bars with a length-diameter ratio from 1:1 to2:1 have shown that the compressive
strength is lower than the tensile strength (Wu 1990). The mode of failure for FRP bars subjected to
longitudinal compression can include transverse tensile failure, fiber micro buckling, or shear
failure. The mode of failure depends on the type of fiber, the fiber-volume fraction, and the type of
resin. Compressive strengths of 55, 78, and 20% of the tensile strength have been reported for GFRP,
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CFRP, and AFRP, respectively (Mallick 1988; Wu 1990). In general, compressive strengths are
higher for bars with higher tensile strengths, except in the case of AFRP, where the fibers exhibit
nonlinear behavior in compression at a relatively low level of stress.
The compressive modulus of elasticity of FRP reinforcing bars appears to be smaller than its tensile
modulus of elasticity. Test reports on samples containing 55 to 60% volume fraction of continuous E-
glass fibers in a matrix of vinyl ester or isophthalic polyester resin indicate a compressive modulus
of elasticity of 5000 to 7000 ksi (35 to 48 GPa) (Wu 1990).
According to reports, the compressive modulus of elasticity is approximately 80% for GFRP, 85%
for CFRP, and 100% for AFRP of the tensile modulus of elasticity for the same product (Mallick
1988; Ehsani 1993). The slightly lower values of modulus of elasticity in the reports may be attributed
to the premature failure in the test resulting from end brooming and internal fiber micro buckling
under compressive loading.
Standard test methods are not yet established to characterize the compressive behavior of FRP bars. If
the compressive properties of a particular FRP bar are needed, these should be obtained from the bar
manufacturer. The manufacturer should provide a description of the test method used to obtain the
reported compression properties.
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• Shear behavior—Most FRP bar composites are relatively weak in interlaminar shear where
layers of unreinforced resin lie between layers of fibers. Because there is usually no reinforcement across
layers, the interlaminar shear strength is governed by the relatively weak polymer matrix.
Orientation of the fibers in an off-axis direction across the layers of fiber will increase the shear
resistance, depending upon the degree of offset. For FRP bars, this can be accomplished by braiding
or winding fibers transverse to the main fibers. Off-axis fibers can also be placed in the pultrusion
process by introducing a continuous strand mat in the roving/ mat creel.
Standard test methods are not yet established to characterize the shear behavior of FRP bars. If the
shear properties of a particular FRP bar are needed, these should be obtained from the bar
manufacturer. The manufacturer should provide a description of the test method used to obtain the
reported shear values.
• Bond behavior—Bond performance of an FRP bar is dependent on the design, manufacturing
process, mechanical properties of the bar itself, and the environmental conditions (Al Dulaijanetal.
1996; Nannietal. 1997; Bakisetal. 1998b; Banketal. 1998; Freimanisetal. 1998).
When anchoring a reinforcing bar in concrete, the bond force can be transferred by:
• Adhesion resistance of the interface, also known as chemical bond;
• Frictional resistance of the interface against slip and
• Mechanical interlock due to irregularity of the interface.
In FRP bars, it is postulated that bond force is transferred through the resin to the reinforcement
fibers, and a bond- shear failure in the resin is also possible. When a bonded deformed bar is
subjected to increasing tension, the adhesion between the bar and the surrounding concrete breaks
down, and deformations on the surface of the bar cause inclined contact forces between the bar and
the surrounding concrete. The stress at the surface of the bar resulting from the force component in
the direction of the bar can be considered the bond stress between the bar and the concrete.
The bond properties of FRP bars have been extensively investigated by numerous researchers
through different types of tests, such as pullout tests, splice tests, and cantilever beams, to determine an
empirical equation for embedment length (Faza and GangaRao 1990; Ehsani et al. 1996a,b;
Benmokrane 1997; Shield et al. 1999; Mosley 2002; Wambeke and Shield 2006; Tighiouart et al.
1999).
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3.6.13 Time-dependent behavior
• Creep rupture—FRP reinforcing bars subjected to a constant load over time can suddenly
fail after a time period called the endurance time. This phenomenon is known as creep rupture (or
static fatigue). Creep rupture is not an issue with steel bars in reinforced concrete except in extremely
high temperatures, such as those encountered in a fire. As the ratio of the sustained tensile stress to the
short-term strength of the FRP bar increases, endurance time decreases. The creep rupture endurance
time can also irreversibly decrease under sufficiently adverse environmental conditions such as high
temperature, ultraviolet radiation exposure, high alkalinity, wet and dry cycles, or freezing-and-thawing
cycles. Literature on the effects of such environments exists, although the extraction of generalized
design criteria is hindered by a lack of standard creep test methods and reporting and the diversity of
constituents and processes used to make proprietary FRP products. In addition, little data are
currently available for endurance times beyond 100 hours. These factors have resulted in design
criteria judged to be conservative until more research has been done on this subject. Several
representative examples of endurance times for bar and bar- like materials follow. No creep strain
data are available in these cases.
In general, carbon fibers are the least susceptible to creep rupture, whereas aramid fibers are
moderately susceptible, and glass fibers are the most susceptible. A comprehensive series of creep
rupture tests was conducted on 0.25 in. (6 mm) diameter smooth FRP bars reinforced with glass,
aramid, and carbon fibers (Yamaguchi et al. 1997). The bars were tested at different load levels at
room temperature in laboratory conditions using split conical anchors. Results indicated that a linear
relationship exists between creep rupture strength and the logarithm of time for times up to nearly
100 hours. The ratios of stress level at creep rupture to the initial strength of the GFRP, AFRP, and
CFRP bars after 500,000 hours (more than 50 years) were linearly extrapolated to be 0.29, 0.47, and
0.93, respectively.
In another extensive investigation, endurance times were determined for braided AFRP bars and
twisted CFRP bars, both using epoxy resin as the matrix material (Ando et al. 1997). These
commercial bars were tested at room tempera- ture in laboratory conditions and were anchored with
an expansive cementitious grout inside of friction-type grips. Bar diameters ranged from 0.26 to
0.6 in. (5 to 15 mm), but were not found to affect the results. The percentage of stress at creep rupture
versus the initial strength after 50 years calculated using a linear relationship extrapolated from data
available to 100 hours was found to be 79% for CFRP, and 66% for AFRP.
An investigation of creep rupture in GFRP bars in room- temperature laboratory conditions was
reported by Seki et al. (1997). The molded E-glass/vinyl ester bars had a small (0.0068 in.2 [4.4
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mm2]) rectangular cross section and integral GFRP tabs. The percentage of initial tensile strength
retained followed a linear relationship with logarithmic time, reaching a value of 55% at an
extrapolated 50-year endurance time.
Creep rupture data characteristics of a 0.5 in. (12.5 mm) diameter commercial CFRP twisted strand
in an indoor environment is available from the manufacturer (Tokyo Rope 2000). The rupture
strength at a projected 100-year endurance time is reported to be 85% of the initial strength.
An extensive investigation of creep deformation (not rupture) in one commercial AFRP and two
commercial CFRP bars tested to 3000 hours has been reported (Saadatmanesh and Tannous
1999a,b). The bars were tested in laboratory air and in room-temperature solutions with a pH equal
to 3 and 12. The bars had diameters between 0.313 to 0.375 in. (8 to 10 mm), and the applied stress was
fixed at 40% of initial strength. The results indicated a slight trend toward higher creep strain in the
larger-diameter bars and in the bars immersed in the acidic solution. Bars tested in air had the lowest
creep strains of the three environments. Considering all environments and materials, the range of
strains recorded after 3000 hours was 0.002 to 0.037%. Creep strains were slightly higher in the
AFRP bar than in the CFRP bars.
For experimental characterization of creep rupture, the designer can refer to the test method
proposed by a committee of JSCE (1997b), the with the specific title of “Test Method on Tensile
Creep-Rupture of Fiber Reinforced Materials, JSCE-E533-1995.” Creep characteristics of FRP bars
can also be determined from pullout test methods cited in ACI 440.3R. Recommendations on
sustained stress limits imposed to avoid creep rupture are provided in the design section of this guide.
• Fatigue—A substantial amount of data for fatigue behavior and life prediction of stand-
alone FRP materials has been generated in the last 30 years (National Research Council 1991).
During most of this time period, the focus of research investigations was on materials suitable for
aero- space applications. Some general observations on the fatigue behavior of FRP materials can
be made, even though the bulk of the data is obtained from FRP specimens intended for aerospace
applications rather than construction. Unless stated otherwise, the cases that follow are based on
flat, unidirectional coupons with approximately 60% fiber-volume fraction and subjected to tension-
tension sinusoidal cyclic loading at:
• A frequency low enough not to cause self-heating;
• Ambient laboratory environments;
• A stress ratio (ratio of minimum applied stress to maximum applied stress) of 0.1; and
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• A direction parallel to the principal fiber alignment. Test conditions that raise the temperature
and moisture content of FRP materials generally degrade the ambient environment fatigue
behavior.
Of all types of current FRP composites for infrastructure applications, CFRP is generally thought
to be the least prone to fatigue failure. On a plot of stress versus the logarithm of the number of cycles
at failure (S-N curve), the average downward slope of CFRP data is usually about 5 to 8% of initial
static strength per decade of logarithmic life. At 1 million cycles, the fatigue strength is generally
between 50 and 70% of initial static strength and is relatively unaffected by realistic moisture and
temperature exposures of concrete structures unless the resin or fiber/resin interface is substantially
degraded by the environment. Some specific reports of data to 10 million cycles indicated a
continued downward trend of 5 to 8% decade in the S-N curve (Curtis 1989).
Individual glass fibers, such as E-glass and S-glass, are generally not prone to fatigue failure.
Individual glass fibers, however, have demonstrated delayed rupture caused by the stress corrosion
induced by the growth of surface flaws in the presence of even minute quantities of moisture in
ambient laboratory environment tests (Mandell and Meier 1983). When many glass fibers are
embedded into a matrix to form an FRP composite, a cyclic tensile fatigue effect of approximately
10% loss in the initial static capacity per decade of logarithmic lifetime has been observed (Mandell
1982). This fatigue effect is thought to be due to fiber-fiber interactions and not is dependent on the
stress corrosion mechanism described for individual fibers. No clear fatigue limit can usually be
defined. Environmental factors play an important role in the fatigue behavior of glass fibers due to
their susceptibility to moisture, alkaline, and acidic solutions.
Aramid fibers, for which substantial durability data are available, appear to behave similarly to
carbon and glass fibers in fatigue. The tension-tension fatigue behavior of an impregnated aramid
fiber bar is excellent. Strength degradation per decade of logarithmic lifetime is approximately 5 to 6%
(Roylance and Roylance 1981). While no distinct endurance limit is known for AFRP, 2-million-
cycle fatigue strengths of commercial AFRP bars for concrete applications have been reported in
the range of 54 to 73% of initial bar strengths (Odagiri et al. 1997). Based on these findings, Odagiri
et al. suggested that the maximum stress be set at 54 to 73% of the initial tensile strength. Because the
slope of the applied stress versus logarithmic creep-rupture time of AFRP is similar to the slope of
the stress versus logarithmic cyclic lifetime data, the individual fibers appear to fail by a strain-
limited creep-rupture process. This failure condition in commercial AFRP bars was noted to be
accelerated by exposure to moisture and elevated temperature (Roylance and Roylance 1981;
Rostasy 1997).
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Although the influence of moisture on the fatigue behavior of unidirectional FRP materials is
generally thought to be detrimental if the resin or fiber/matrix interface is degraded, research
findings are inconclusive because the performance depends on fiber and matrix types,
preconditioning methods, solution content, and the environmental condition during fatigue (Hayes
et al. 1998; Rahman et al. 1997). In addition, factors such as gripping and presence of concrete
surrounding the bar during the fatigue test need to be considered.
Fatigue strength of CFRP bars encased in concrete has been observed to decrease when the
environmental temperature increases from 68 to 104 °F (20 to 40 °C) (Adimi et al. 1998). In this
same investigation, the endurance limit was found to be inversely proportional to the loading
frequency. It was also found that higher cyclic loading frequencies in the 0.5 to 8 Hz range
corresponded to higher bar temperatures due to sliding friction. Thus, an endurance limit at 1 Hz
could be more than 10 times higher than that at 5 Hz. In the cited investigation, a stress ratio
(minimum stress divided by maximum stress) of 0.1 and a maximum stress of 50% of initial strength
resulted in run outs of greater than 400,000 cycles when the loading frequency was 0.5 Hz. These run
out specimens had no loss of residual tensile strength.
It has been found with CFRP bars that the endurance limit also depends on the mean stress and the
ratio of maximum- to-minimum cyclic stress. Higher mean stress or a lower stress ratio (minimum
divided by maximum) will cause a reduction in the endurance limit (Rahman and Kingsley
1996; Saadatmanesh and Tannous 1999a).
Even though GFRP is weaker than steel in shear, fatigue tests on specimens with unbonded GFRP
dowel bars have shown fatigue behavior similar to that of steel dowel bars for cyclic transverse shear
loading of up to 10 million cycles. The test results and the stiffness calculations have shown that
an equivalent performance can be achieved between FRP and steel bars subjected to transverse shear
by changing some of the parameters, such as diameter, spacing, or both (Porter et al. 1993; Hughes
and Porter 1996).
The addition of ribs, wraps, and other types of deformations improve the bond behavior of FRP bars.
Such deformations, however, have been shown to induce local stress concentrations that significantly
affect the performance of a GFRP bar under fatigue loading situations (Katz 1998). Local stress
concentrations degrade fatigue performance by imposing multiaxial stresses that serve to increase
matrix-dominated damage mechanisms normally suppressed in fiber-dominated composite materials.
Additional fiber-dominated damage mechanisms can be also activated near deformations, depending
on the construction of the bar.
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The effect of fatigue on the bond of deformed GFRP bars embedded in concrete has been
investigated in detail using specialized bond tests (Sippel and Mayer 1996; Bakis et al. 1998a; Katz
2000). Different GFRP materials, environments, and test methods were followed in each cited case,
and the results indicated that bond strength can either increase, decrease, or remain the same following
cyclic loading. Bond fatigue behavior has not been sufficiently investigated to date, and conservative
design criteria based on specific materials and experimental conditions are recommended. Design
limitations on fatigue stress ranges for FRP bars ultimately depend on the manufacturing process of
the FRP bar, environmental conditions, and the type of fatigue load being applied. Given the ongoing
development in the manufacturing process of FRP bars, conservative design criteria should be used
for all commercially available FRP bars.
With regard to the fatigue characteristics of FRP bars, the designer is referred to the provisional
standard test methods cited in ACI 440.3R. The designer should always consult with the bar
manufacturer for fatigue response properties.
• Effects of high temperatures and fire
The use of FRP reinforcement is not recommended for structures in which fire resistance is
essential to maintain structural integrity. Because FRP reinforcement is embedded in concrete, the
reinforcement cannot burn due to a lack of oxygen however, the polymers will soften due to the
excessive heat. The temperature at which a polymer will soften is known as the glass-transition
temperature Tg. Beyond the Tg, the elastic modulus of a polymer is significantly reduced due to
changes in its molecular structure. The value of Tg depends on the type of resin, but is normally
in the region of 150 to 250 °F (65 to 120 °C) (Bootle et al. 2001). In a composite material, the
fibers, which exhibit better thermal properties than the resin, can continue to support some load in
the longitudinal direction; however, the tensile properties of the overall composite are reduced due
to a reduction in force transfer between fibers through bond to the resin. Test results have indicated
that temperatures of 480 °F (250 °C), much higher than the Tg, will reduce the tensile strength of
GFRP and CFRP bars in excess of 20% (Kumahara et al.1993). Other properties more directly
affected by the shear transfer through the resin, such as shear and bending strength, are reduced
significantly at temperatures above the Tg (Wang and Evans 1995). For purposes of design, some
researchers recommended that materials have a Tg at least 54 °F (30 °C) above the maximum expected
temperature (Kollár and Springer et al. 2003).
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For FRP-reinforced concrete, the properties of the polymer at the surface of the bar are essential in
maintaining bond between FRP and concrete. At a temperature close to its Tg, however, the
mechanical properties of the polymer are significantly reduced, and the polymer is not able to transfer
stresses from the concrete to the fibers. One study as the limiting temperature for carbon fibers even
if they might be partially isolated from oxygen by uncracked concrete and charred polymer
(Lamouroux et al. 1999).
Locally, such behavior can result in increased crack widths and deflections. Structural collapse can
be avoided if high temperatures are not experienced at the end regions of FRP bars, allowing
anchorage to be maintained. Structural collapse can occur if all anchorage is lost due to softening of
the polymer or if the temperature rises above the temperature threshold of the fibers themselves. The
latter can occur at temperatures near 1800 ºF (980 ºC) for glass fibers and 350 ºF (175 ºC) for aramid
fibers. Carbon fibers are capable of resisting temperatures in excess of 3000 ºF (1600 ºC). The
behavior and endurance of FRP-reinforced concrete structures under exposure to fire and high heat is
still not well under- stood, and further research in this area is required. ACI 216R may be used for
an estimation of temperatures at various depths of a concrete section.
3.6.14 Chemical Properties
Cured resins (matrix) hold the fibers together for shear transfer. Their chemical resistance against
pH, strength, stiffness, and viscoelastic properties are related to their chemical structure. The
presence of moisture can lead to chemical changes, potentially affecting their properties. FRP
composites employed in marine applications are subjected to hygro-thermal stresses and moisture
induced chemical and mechanical property variations. Water penetrates FRPs through two
processes: diffusion through the resin, and flow through cracks or flaws. During diffusion, absorbed
water is not in the liquid form, but consists of molecules or groups of molecules that are linked
together by hydrogen bonds to the polymer. The molecules dissolved in the surface layer of the
polymer migrate into the bulk of the material under a concentration gradient. Water penetration
into cracks or other flaws occurs by capillary flow. Water also penetrates at the fiber matrix
interface. It is reported that the primary mechanism of moisture pickup is diffusion through resin,
and transfer of moisture through cracks is an after effect. Moisture pickup leads to loss of chemical
energy, which is attributed to hydrolytic scission of ester groups. However, increased hydrostatic
pressure reduces water uptake due to closing of micro cracks. Hence, it is important to maintain
good quality control during manufacturing including complete fiber wet out and high degree of
curing to achieve low void content (preferably less than 0.3%). In addition, proper design may be
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necessary to counter any excessive stresses or stress concentrations induced on structural materials
during fabrication and service.
Diffusion of water into the resin may cause swelling stresses. The equilibrium content of water
determines the magnitude of swelling stresses. The chemical composition of resin influences the
solubility of water in the resin and its susceptibility to hydrolysis. Exposure of composites to moisture
for longer duration results in resin (matrix) plasticization and interface bond strength reduction.
Hence, surfaces of moisture exposed composites are finished with thin layer of gel coat or acrylic
resins to create watertight and water-repellent surfaces.
3.7 Applications Fibre-reinforced plastics are best suited for any design program that demands weight savings,
precision engineering, finite tolerances, and the simplification of parts in both production and
operation. A moulded polymer artefact is cheaper, faster, and easier to manufacture than cast
aluminium or steel artefact, and maintains similar and sometimes better tolerances and material
strengths.
3.7.1 Applications of FRP Composites in Industrial Construction
In the past three decades FRP composites have won an increasing mass fraction of military and civil
applications. Significant investments from private and public funds were made toward research,
development, testing, fabrication and demonstration projects. Confidence in using composite
materials increased dramatically. This was also a period of great innovation in manufacturing,
assembly and repair method development.
The construction industry has also become a major end user of FRP composites due to certain
advantages that will be briefly discussed below. Nowadays the construction industry utilizes FRP
composites based on glass, carbon and aramid fibres embedded in matrices made of polyester, epoxy
and vynilester resins Recently basalt fibres have been introduced especially in application requiring
high temperature exploitation .
The range of properties of FRP composites as well as the formability of FRP composite elements
provides a large variety of load bearing and non structural applications for civil engineering area.
Linear elements, plate and shells elements and folded structures can be easily fabricated and
assembled in different types of buildings or structures.
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Figure 4 FRP Pultruded sections and chemical platform with these products
.
Figure 5 FRP composite tanks: a – horizontal tanks [7]; b – vertical tanks [8]. Fabrication procedures have been specially developed for FRP composite elements and structures;
consequently they have penetrated almost any domain of industrial and agricultural buildings.
Mass production or niche fabrication are currently providing a variety of structural shapes or bars
fabricated by pultrusion and platforms for chemical industry are especially made of these profiles
(Fig. 5). Transport and storage construction elements such as pipes and tanks, are produced using
filament winding (Fig. 5).
Large scale elements with complicated shapes, covering parts for roofs (Figs. 6 and 7), are made
using hand lay-up and/or spray-up.
Figure 6 Large scale GFR polyester dome and skylight.
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Figure 7 Folded skylight on an industrial workshop; double curved shells for an industrial roof.
An application of increasing importance is the use of composites in wind turbine blades (Fig.8 a).
Blades of unusual lengths (up to 125 m) made of a sandwich construction consisting of FRP facings
and light weight foam cores have become familiar in many regions where wind speeds are high and
the wind blows almost continuously. These wind turbines provide a valuable source of clean and
renewable energy.
The offshore platforms have become a new important sector of use for advanced polymer
composites. Particular examples for the application of FRP composites for the offshore construction
include: firewater piping, sea water piping, grating, storage vessels, fire and blast walls (Fig. 8 b).
Recent developments of fibre glass pipes have overcome one of their major drawbacks, namely
leakage [10]. Carbon fibre reinforced polymers (CFRP) composites are utilized not only in
underwater piping but also in structural parts of the platform. On the offshore platform the initial
fears of fire hazard decreased after the research
Figure 8 – a – Blades made of glass fibre reinforced polymer (GFRP) [4]; b – FRP composite components for an offshore platform [6].
work showed that composite laminates thicker than 8 mm perform better than steel in a major fire.
The stairways and walkways are also made of composites for weight saving and corrosion resistance.
Even the cables and ropes made of steel are now being replaced by similar items made of aramid or
high modulus polyethylene fibres.
3.7.2 Application of FRP Composite Systems in Strengthening .
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Strengthening rehabilitation of deteriorated and damaged industrial constructions has become one of
the major issues for civil and industrial engineers all over the world. The main reasons for structural
rehabilitation of the structural elements include: changes in the use of structure and degradation of
the structure. Changes in the use of structure include increased live load or dead load, change in the
load path, new loading requirements and modernization of design practice. Degradation of the
structure comprises: corrosion as a mechanism of structural degradation, fatigue of construction
materials, hazard events, construction errors due to poor construction workmanship or the use of
inferior materials.
FRP composites are recommended for structural rehabilitation solutions because the materials
utilized are light-weight, corrosion resistant and suitable to tailored design. In addition, the FRP
composite products are easily attached to surfaces of elements made of traditional material, require
less labour force and do not modify the dynamic and the seismic characteristics of the load bearing
elements.
A few case studies on the FRP composite application in structural rehabilitation works are presented
in the following.
A comprehensive theoretical and experimental project has been carried out by the authors at the
Faculty of Civil Engineering and Building Services, “Gh. Asachi” Technical University of Iaşi on
the strengthening possibilities with advanced polymeric composites of a complete industrial hall. All
structural members and cladding element have been analysed and the proposed solutions are
illustrated in Fig. 7 .
Industrial chimneys are special industrial structures exploited under severe wind, seismic and
temperature difference conditions.
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Figure 9 Strengthening solutions using FRP based solutions for an industrial hall: a – wall strengthening with
bidirectional strips (1) and unidirectional strips (2); b – column strengthening using discrete strips (3), continuous
wrapping (4) and combined discrete and continuous wrapping (5); c – discrete bending strengthening solutions
for reinforced concrete (RC) girders and continuous membranes (6); d – shear strengthening solutions for RC
girders using bottom flange clamping of inclined strips for runway girders (7) and (8) and U-shaped bands (9); e
– strengthening solution for main transverse girders including end textile clamping (10), plate bonding (11) and
discrete clamping made of composite strips (12); f – plate bonded ribs for roof elements (13).
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Chimneys made of brick and reinforced concrete have been structurally assessed and strengthening
solutions have been proposed.
a b
c d
Figure 10 Composite based strengthening solutions for industrial chimneys: a – wrapping with carbon fibre
balanced fabric; b – confinement with composite hoop strips; c – helicoidal spiral made of composite cable; d –
prefabricated composite membranes [14].
Civil-Inland and Offshore Structural Repairs
FRP composites are ideally suited as quick and effective structural repair tool because of their
lightweight, high strength and corrosion resistance. Bridge repair using FRP composites is a major
success story and many details can be found in the book authored by GangaRao, Taly, and Vijay,
entitled “Reinforced Concrete Design with FRP Composites” (2007). Storage tanks for liquids are
ideal application of FRP using corrosion and solvent resistant resins. FRP tanks are easy to install,
more economical than the conventional materials, and they have better service life. Researchers
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visualize that within a few years large number of tanks, starting from municipal water tanks to large
petrochemical tanks, will be built with FRP composites (Chakrabarti et al., 2002).
The availability of resins that cure under water has extended the FRP wrap application to
substructure elements such as partially submerged piles that are damaged (refer to Chapter 8). Also,
FRP composites have been used in offshore platforms where corrosion in the presence of seawater
is a major concern. Some of the current FRP applications are (Moahmoud et al 2009): i. Low
pressure pipes
ii. Diesel storage tanks, lube tanks, and utility tanks
iii. Walkway gratings, stair steps, and handrails
iv. Cable ladders and trays
v. Fire protection panels and sections of accommodation modules vi. Buoys and floats
vii. Strengthening of primary steel structures
viii. Helicopter landing decks
ix. Walls and floors to provide protection against blast and fire
The higher cost of constructing offshore structures with composites compared with welded steel is
a concern. However, the significant through-life cost savings can be gained with composites due to
reduced maintenance and premature replacement of corroded structures.
3.7.3 Army, Marine, and Related Applications In 2000, the French Water Authority (Voies Navigables de France) introduced a new generation
hybrid lock gate developed by DGA - DCN Lorient, designed for use on small or Freycinet-type
inland waterway networks (locks under 6.5 meters in width with mitre-type gates). The hybrid lock
gate is made of FRP material (two surface laminates of 5.2m wide and up to 8m tall with horizontal
stiffeners) and strengthened with stainless steel frame and its self weight is only 40% of steel
(Advanced Material and Composites News, 2000). Light weight results in easy transportation,
placement, and facilitates hand assembly
Now different types of hybrid FRP gates (12‟x12‟) with steel core are available commercially for
water-flow-control applications including sluice gates, slide gates, stop gates, weir gates and flap
gates. They are reported to be capable of holding water pressure up to 100ft (Plasti-Fab.com).
Submersible pump manufacturers now offer FRP packaged pump stations, for general civil works,
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particularly for sewage and storm water pumping, to take advantage of lightweight, and corrosion
resistance properties of FRP (flygetus.com).
3.7.4 FRP Pipes for Marine Applications
FRP pipes such as those required for marine applications are designed with high safety factors (6
to 12), depending on the loading and application parameters such as stress levels and stress
concentrations, stress (pressure) surges, operating temperatures, water hammer effects etc. FRP
pipes are typically designed on allowable strain basis with due consideration provided to pressure
and temperature such that repeated residual strain accumulation and damage are prevented;
however, FRP structures are typically designed for deflection limit states.
Large FRP pipe systems with diameters up to 13ft and a minimum of 50-year design life are being
manufactured for the following infrastructure applications:
Large potable water transmission pipeline
Slip lining of corroded large concrete sewer pipes and tunnels
Large gravity sewer and storm water drains
Large siphons and culverts
River and seawater intakes and outfalls
Power plant circulating and cooling water lines
Large power plant penstocks
Large irrigation pipelines
Large pump station headers
Figure 11: Very large FRP pipe systems from Future Pipe Industries (www.futurepipe.com)
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3.7.5 FRP Piling
A full-scale feasibility assessment was conducted on different types of FRP composite-bearing
piles at Port Elizabeth, NJ. The study consisted of the following:
Evaluation of equivalent mechanical short-term properties of the composite material
include: elastic modulus for the initial loading quasilinear phase, axial compression
strength, inertia moment, and critical buckling load. These FRP composites consisted of
recycled plastic reinforced by fiberglass rebar (SEAPILE™ composite marine piles),
recycled thermo plastic reinforced by steel bars, and recycled plastic reinforced with
randomly distributed fiberglass (Trimax), manufactured respectively by Seaward
International Inc., Plastic Piling, Inc., and U.S. Plastic Lumber (Juran and Komornik, 2006).
Response analysis of FRP piles under static and dynamic loads.
Feasibility estimate of installing FRP piles using standard pile driving equipment, capacity,
and constructability.
Figure 12 Composite marine piles from different manufacturers were tested. Shown in pictures: SEAPILE, PPI
and Trimax piles, (Juran and Komornik, 2006)
As a result of the study related to FRP piles, Juran and Komornik (2006) concluded that FRP
composite piles could be used as an alternative engineering solution for deep foundations. These
authors recommended further research regarding time-dependent stress-response of composite
recycled plastic material to be done before a wider spread use of these piles. One of the main
concerns was that FRP piles may undergo higher deformations under sustained loads than metals
(Juran and Komornik, 2006). However, creep studies on FRP reinforced concrete members and
FRP shapes have indicate an excellent creep performance of those FRP members when provided
with proper fiber/fabric architecture and fiber volume fraction. Lower stiffness of FRP results in
higher deformation than metals and this disadvantage has to be overcome by designing innovative
shapes with higher moment of inertia (Batra et al., 2009).
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3.7.6 Other FRP applications
FRP manholes (Fig. 13) are commercially available with diameters up to 72 inches. Similarly, aircraft
structures made of composites (Fig. 14) are gaining popularity because of their high strength to
weight ratio.
Figure 13 Composite marine piles from different manufacturers were tested. Shown in pictures: SEAPILE, PPI
and Trimax piles, (Juran and Komornik, 2006)
Figure 14 Boeing 787 Dreamliner, the world's first major commercial airliner to use composite materials for
most of its construction (www.boeing.com)
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3.7.7 FRP Design, Development and Field Implementation by CFC-WVU and Others
Some of the FRP design, development, and field implementation activities carried out by
CFCWVU are shown in Figs. 15 through 2.16. This design, manufacturing, field implementation,
and monitoring work by the CFC-WVU over last two decades has contributed to the development
and publication of design documents, specifications, various short courses, conferences, and
technology transfer activities. Some of the related bridge applications in Switzerland and USA are
also shown in Fig. 16.
Figure 15 FRP Design and Applications by the CFC-WVU, (Top L to R) – i) FRP dowels in highway pavement
(Elkins, WV), ii) FRP reinforcement for concrete highway pavement (Charleston, WV), and iii) FRP
thermoplastic tie for railroads (Moorefield, WV); (bottom L to R) - i) FRP pavement panels (Morgantown, WV,
iii) thermoplastic FRP offset block for guardrails, (Morgantown, WV) (Courtesy: CFC-WVU).
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Figure 16 FRP bridge deck shapes designed and field implemented in WV and Ohio by the CFC-WVU
(Courtesy: CFC-WVU)
Figure 17 FRP application for ship decks L); successful testing of fire resistant FRP panel at 5800 degree F with
acetylene torch for 5 minute at CFC-WVU. (Courtesy: CFC-WVU)
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Figure 18 FRP Inspection Walkway Blennerhassett Bridge, Parkersburg, WV (Courtesy: CFC-WVU)
Figure 19 Examples of FRP application for bridges: (Top L to R)- i) Carbon cables used in bottom chord, Kleine
Emme Bridge, Switzerland (Courtesy: Dr. Urs Meier); ii) FRP pedestrian bridge over 9th Street, NY; (bottom L to R)-
iii) Neal Bridge, Maine with FRP tubes (courtesy: NYTimes.com); iv) Proposed FRP Pedestrian Bridge at West
Virginia University, Morgantown)
3.7.8 Application of FRP as Rebar
FRP is used in many of the project as rebar which give a very high durability to the structure as
well as it is very light in weight so the structure weight also reduce. Majorly FRP is used in the
bridge deck
The material characteristics of FRP reinforcement need to be considered when determining whether
FRP reinforcement is suitable or necessary in a particular structure The corrosion resistance of FRP
reinforcement is a significant benefit for structures in highly corrosive environments such as seawalls
and other marine structures, bridge decks and superstructures exposed to deicing salts, and pavements
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treated with deicing salts. In structures supporting magnetic resonance imaging (MRI) units or other
equipment sensitive to electromagnetic fields, the nonmagnetic properties of FRP reinforcement are
unrivaled. FRP reinforcement has a non-ductile behavior that is partially compensated by its high
tensile strength. The use of FRP reinforcement should be limited to structures that will significantly
benefit from other properties such as the noncorrosive or nonconductive behavior of its materials. Due
to lack of experience in its use, FRP reinforcement is not recommended for moment frames or zones
where moment redistribution is required.
FRP reinforcement should not be relied on to resist compression. Available data indicate that the
compressive modulus of FRP bars is lower than its tensile modulus. Due to the combined effect of
this behavior and the relatively lower modulus of FRP compared with steel, the maximum contribution
of compression FRP reinforcement calculated at crushing of concrete (typically at εcu = 0.003) is small.
Therefore, FRP reinforcement should neither be used as reinforcement in columns nor other in
compression members, nor as compression reinforcement in flexural members. It is acceptable for FRP
tension reinforcement to experience compression due to moment reversals or changes in load pattern.
The compressive strength of the FRP reinforcement should not, however, be neglected. Further
research is needed in this area.
Commercially available FRP reinforcing materials are made of continuous aramid FRP (AFRP),
carbon FRP (CFRP), or GFRP fibers embedded in a resin matrix (ACI 440R). Typical FRP
reinforcement products are grids, bars, fabrics, and ropes. The bars have various types of cross-
sectional shapes (square, round, solid, and hollow) and deformation systems (exterior wound fibers,
sand coatings, and separately formed deformations). A sample of five distinctly different GFRP
reinforcing bars is shown in Fig. 20.
Figure 20 Commercially available GFRP reinforcing bars
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Chapter 4 Code Provision
1.1 Standard test methods for FRP bars and laminates ACI 440, ASTM, CEN (European Committee for Standardization), CSA (Canadian Standards Association),
and JSCE (Japan Society for Civil Engineering) provide guidelines on different test methods. These
guidelines provide details about preparing the samples, conditioning the specimens, test procedures, and
calculations. Some of these are listed in Tables 4.1 It should be noted that these tables do not provide a
complete list and some related aspects and specifications are also listed in appendix C.
Some of the standard test methods available for testing FRP laminates and bars are provided in Tables 4.2
Brief description on these standards is provided in Appendix C. Many of these specifications have been
developed after the publication of ETL 1110-2-548. These specifications are useful for both updating the
information presented in ETL 1110-2-548 and design of FRP structures.
Table 4.1: Available standard test methods for FRP laminates used as strengthening or repair materials
adopted from ACI 440.3R-04
Property Test method Property Test method
Direct tension pull-off ASTM-D4551
ACI 440-L.1
Tensile strength and modulus ASTM-D3039
ACI 440-L.2 Lap shear strength ASTM-D3165
ASTM-D3528
ACI 440-L.3
Bond strength ASTM-D4551
ASTM-DC882
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Table 4.2: Available standard test methods for FRP bars used for reinforcing or prestressing concrete
adopted from ACI 440.3R-04
Property Test method Property Test method
Cross-sectional area ACI 440 –B.1 Longitudal tensile strength and
modulus ASTM-D3916
ACI 440-B.2 Bond properties ASTM-A944
ACI 440-B.3
Shear Strength ASTM-D5379
ASTM-D3846
ASTM-D2344
ASTM-D4475
ACI 440-B.4 Bent bar capacity ACI-B.5 Durability properties ACI 440-B.6 Fatigue properties ASTM-D3479
ACI 440-B.7
Creep properties ASTM D-2990
ACI 440-B.8 Relaxation properties ASTM-D2990
ASTM-E328
ACI 440-B.9
Anchorage properties ACI 440-B.10
Tensile properties of deflected
bars ACI 440-B.11 Effect of corner radius on strength ACI 440-B.12
Flexural properties ASTM-D790
ASTM-D4476
Coefficient of thermal expansion ASTM-E831
ASTM-D696 Glass transition temperature ASTM-E1356
ASTM-E1640
ASTM-D648
ASTM-E2092
Volume fraction ASTM-D3171
ASTM-D2584
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Chapter 5 Manual Design of FRP Beam In this chapter manual design problem is explained with all the design procedure as per ACI440.04r and all the tables and equations references are given which are explained in the code. The design problem is A simply supported, normal weight concrete beam with fc’ = 27.6 MPa is needed in a facility to support a machine. The beam is an interior beam. The beam is to be designed to carry a service load of wLL =5.8 kN/m an a superimposed service load od wSDL =3.0 kN/m over a span of l =3.35m.
Step 1—Estimate the appropriate cross-sectional dimensions of the beam.
An initial value for the depth of a simply supported reinforced concrete beam can be estimated
from Table 8.2.
H = L/10
h = 3.35/10 = 0.335m
Recognizing that the values suggested in the table are meant only to be a starting point for design,
try h = 304mm
Try h = 305mm <335mm
Assuming 16mm dia bars for main
Assuming 9.5mm dia for shear
Cover = 38mm
A minimum width of approx. 178mm is required when using two 16mm or two 19mm bars with
9.5 mm stirrups.
b = 200 mm l = 3.35 m
d = 250 mm
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Try b = 0.178 m
An effective depth of the section is estimated using 1-1/2 in. clear cover
Estimated d = h − cover − db,shear − d/2
d = 305mm-38mm-9.5mm-16mm/2
= 250 mm
Step 2—Compute the factored load.
The uniformly distributed dead load can be computed including the self-weight of the beam.
WDL = WSDL + WSW
= (3kN/m)+(0.178m)(0.305m)(24kN/m3)
= 4.3kN/m
Compute the factored uniform load and ultimate Moment
Wu = 1.2 WDL + 1.7 WLL
= 1.2(4.3kN/m)+1.7(5.8kN/m)
= 14.4 kN/m
Mu = Wul2/8
= ((14.4kN/m)(3.35m)2)/8
= 20.2kNm
Step 3—Compute the design rupture stress of the FRP bars.
The beam will be located in an interior conditioned space. Therefore, for glass FRP bars, an
environmental reduction factor CE of 0.80 is as per Table 7.1.
ffu = CE f*fu
= (0.8)(620.6kN/mm2)
= 496 kN/mm2
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Step 4— Determine the area of GFRP bars required for flexural strength.
Find the reinforcement ratio required for flexural strength by trial and error using Eq. (8-1), (8-4d),
and (8-5).
Assuming an initial amount of FRP reinforcement
Trying for 16mm of bars
Computed the balanced FRP reinforcement ratio
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= (440800N/mm2)(0.003) = 0.0086
(44,800N/mm2)(0.003)+(496N/mm2)
= 400mm2 = 0.009
(178mm)(250 mm)
Where:- ρfb = FRP reinforcement ratio producing balanced
strain conditions
ρf = FRP reinforcement ratio
β1 = F a c t o r taken as 0.85 for concrete strength fc′ up to and including 4000 psi (28 MPa). For strength
above 4000 psi (28 MPa), this factor is reduced continuously at a rate of 0.05 per each 1000 psi (7 MPa) of
strength in excess of 4000 psi (28 MPa), but is not taken less than 0.65
fc′ = Specified Compressive Strength Of Concrete, Psi (Mpa)
ffu = Design Tensile Strength Of FRP, Considering Reductions For Service Environment, Psi (Mpa) Ef = Design Or Guaranteed Modulus Of Elasticity Of FRP Defined As Mean Modulus Of Sample Of Test
Specimens (Ef = Ef,Ave), Psi (Mpa)
εcu = Ultimate Strain In Concrete
Af = Area Of FRP Reinforcement, In.2 (Mm2)
b = Width Of Rectangular Cross Section, In. (Mm)
d = Distance From Extreme Compression Fiber To Centroid Of Tension Reinforcement, In. (Mm)
Where ff = Stress In FRP Reinforcement In Tension, psi (MPa)
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A = ((44,800N/mm2)(0.003))2 = 4516
4
B = 0.85(0.85)(27.6N/mm2)(44,800N/mm2)(0.003) = 297800
0.009
C = 0.5(44,800N/mm2)(0.003) = 67.2
= N/mm2
= 43.9kN.mm
Mn = Nominal Moment Capacity, Lb-In. (N-mm)
Mu= Factored Moment At Section, Lb-In. (N-mm)
= 0.562
ΦMn = 24.7kNm >= Mu =20.2kNm
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Step 5—Check the crack width.
Compute the stress level in the FRP bars under dead load plus live load.
= 6.03kNm
= 8.14kNm
= 6.03+8.14 = 14.17 kNm
= 1.8
= 0.165
= 149.9 N/mm2
Where:-
fc′= specified compressive strength of concrete, psi (MPa)
k = ratio of depth of neutral axis to reinforcement depth
ff= stress in FRP reinforcement in tension, psi (MPa)
Determine the strain gradient used to transform
Determine the strain gradient used to transform reinforcement level strains to the near surface of
the beam where cracking is expected
= 1.263
β = ratio of distance from neutral axis to extreme tension fiber to distance from neutral axis to
center of tensile reinforcement h = overall height of flexural member, in. (mm)
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Calculate the distance from the extreme tension fiber of the concrete to the centerline of the flexural
reinforcement.
dc = h –d = 55mm
Calculate bar spacing s.
s = b – 2dc = 68 mm
Compare the crack width from Eq. (8-9) using the recommended value of kb = 1.4 for deformed
FRP bars.
= 0.77 mm
Note that it is preferable to use bars with smaller diameters to mitigate cracking. For example,
using three φ12.7 bars will result in approximately the same area of FRP and nearly the same
effective depth however, the width of the member would need to be increased.
Crack width limitation controls the design. Try larger amount of FRP reinforcement.
To maintain b= 0.178 mm
Try 2 φ 19 = Af = 567 mm2
= 248 mm
= 0.0128
Calculate the new capacity.
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A = 4156
B = 209,400
C = 672
= 395.3 N/mm2
Mn = 49.4 kNm
P0 =.0128 > 1.4fb = 0.012
ΦMn = 32.1 kN.m >= M0 = 22.3 kNm
= 0.193
= 107.7 N/mm2
= 1.285
Calculate the distance from the extreme tension fiber of the concrete to the centerline of the flexural
reinforcement.
dc = h –d = 57 mm
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Calculate bar spacing s.
= 64 mm
Compare the crack width from Eq. (8-9) to the design limit using the default value of kb = 1.4 for
deformed FRP bars.
= 0.57 mm < 0.7 mm OK
Step 6—Check the long-term deflection of the beam
Compute the gross moment of inertia for the section.
= 4209 X 100 mm4
Ig= Gross moment of inertia
Calculate the cracked section properties and cracking moment.
= 3.26 N/mm2
= 9.00 kN.m
= 4.47 X 107 mm4
Compute the modification factor βd.
= 0.03
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Compute the deflection due to dead load plus live load.
= 6.76 X 100 mm4
= 10 mm
Where:-
Ie= effective moment of inertia
βd = reduction coefficient used in calculating deflection
Ma = maximum moment in member at stage deflection is computed, lb-in. (N-mm)
Δ = Deflection
Compute the deflection due to dead load alone and live load alone.
= 4.3 mm
= 5.7 mm
Compute the multiplier for time-dependent deflection using a ξ = 2.0 (recommended by ACI 318
for a duration of more than 5 years).
λ = 0.60ξ
λ=1.2
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Compute the long-term deflection (initial deflection due to live load plus the time-dependent
deflection due to sustained loads).
= 12.2 mm
Check computed deflection against deflection limitations.
= 12.2 mm < 14mm
Step 7—Check the creep rupture stress limits.
Compute the moment due to all sustained loads (dead load plus 20% of the live load).
= 7.66 kN.m
Ms = moment due to sustained load, lb-in. (N-mm)
Compute the sustained stress level in the FRP bars.
= 58.2n/mm2
Check the stress limits given in Table 8.2 for glass FRP bars.
58.2 N/mm0 <= 0.20(496) = 99.2 N/mm2
ff,s = stress level induced in FRP by sustained loads, psi (MPa) Step 8—Design for shear.
Determine the factored shear demand at a distance d from the support
= 20.6 kN
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Compute the shear contribution of the concrete for an FRP-reinforced member.
= 17.9 kN
FRP shear reinforcement will be required. The FRP shear reinforcement will be assumed to be No.
3 closed stirrups oriented vertically. To determine the amount of FRP shear reinforcement required,
the effective stress level in the FRP shear reinforcement must be determined. This stress level may
be governed by the allowable stress in the stirrup at the location of a bend, which is computed as
follows:
= 223.2 N/mm2
The design stress of FRP stirrup is limited to:
= 179.2 N/mm2<= 223.2 N/mm2
The required spacing of the FRP stirrups can be computed by rearranging Eq. (9-4).
= 660 mm
S<= 248/2 = 124 mm
S<= 600
Check maximum spacing limit = d/2 or 24 in. Equation (9-7) for minimum amount of shear
reinforcement can be rearranged as s ≤ Afv ffv/0.35bw (SI).
According to Afv ffv/0.35bw
S<= 477 mm
Use of 10 stirrups at 120 mm on center
Step 9—Check that the required bar stress can be developed, and that anchorage bond is
sufficient.
Find C = min(cover to the center of the bar, 1/2 c-o-c spacing)
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9 mm c/c 120 mm
C = min (38 mm + 9.5 mm +19/2 .64/2)
C = 32 mm
Determine the bar stress that is developable at midspan for the provided embedment length le = l/2.
395.3N/mm0 > 496 N/mm2 ,so flexural
strength is not limited by bond
Compare developable bar stress ffe with required bar stress for flexural strength ff.
Check anchorage development in positive moment region.
= 70 mm
Check the development of the positive reinforcement at the simply supported end.
= 2025 mm
The development length of the section is 2.025 m from the mid point if the bar which should be
covered inside the section in case of simply supported section.
Results
The ultimate load carrying capacity of the beam is 14.4 kN/m and the moment in the beam is 20.2
kNm, the stress in the reinforcement is 149.9 N/mm2 so we use 2 bars of 19 mm dia. With spacing
of 60 mm c/c and the stirrups will be of 9 mm dia with a spacing of 120 mm c/c and the max.
Deflection is 12.2 mm
50 mm
b = 200 mm l = 3.35 m
d = 250 mm
` 19mm c/c 60 mm
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Chapter 6 Analysis of Beam Using FEM General
To provide a detailed review of the body of literature related to reinforced concrete in its entirety
would be too immense to address in this paper. However, there are many good references that can be
used as a starting point for research (ACI 1978,MacGregor 1992, Nawy 2000). This literature review
and introduction will focus on recent contributions related to FEA and past efforts most closely
related to the needs of the present work.
The use of FEA has been the preferred method to study the behavior of concrete (For economic
reasons). William and Tanabe (2001) contains a collection of papers concerning finite element
analysis of reinforced concrete structures. This collection contains areas of study such as: seismic
behavior of structures, cyclic loading of reinforced concrete columns, shear failure of reinforced
concrete beams, and concrete steel bond models.
Shing and Tanabe (2001) also put together a collection of papers dealing with In-elastic
behavior of reinforced concrete structures under seismic loads. The monograph contains
contributions that outline applications of the finite element method for studying post-peak cyclic
behavior and ductility of reinforced concrete beam, the analysis of reinforced concrete components
in bridge seismic design, the analysis of reinforced concrete beam-column bridge connections, and
the modeling of the shear behavior of reinforced concrete bridge structures.
The focus of these most recent efforts is with bridges, columns, and seismic design. The focus
of this seminar is to study of non-prestressed flexural members.
AMR A. ABDELRAHMAN(1995) give the basic behavior of non- prestressed member with
full experimental data and the specification of the section with its dimension and the number of
strands used in every section during casting. He also provides the property of FRP material used in
the section and the results obtained after the testing of the section.
The following is a review and synthesis of efforts most relevant to this Seminar discussing
FEA applications, experimental testing, and concrete material models.
Finite Element Analysis
Finite element analysis is an effective method of determining the static performance of
structures for the reasons which are saving in design time cost effective in construction and increase
the safety of the structure. Previously it is necessary to use advanced mathematical methods in
analysis large structures, such as bridges tall buildings and other more accuracy generally required
more elaborate techniques and therefore a large friction of the designer’s time could be devoted to
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mathematical analysis. Finite element methods free designer’s from the need to concentrate on
mathematical calculation and allow them to spend more time on accurate representation of
the intended structure and review of the calculated performance (Smith, 1988). Furthermore by using
the programs with interactive graphical facilities it is possible to generate finite element models of
complex structures with considerable ease and to obtain the results in a convenient readily
assimilated form. This may save valuable design time. More accurate analysis of structure is possible
by the finite element method leading to economics in materials and construction also in enhancing
the overall safety (DeSalvo and Swanson, 1985).
However in order to use computer time and design time effectively it is important to plan the
analysis strategy carefully. Before a series of dynamic tests carry out in the field a complete three-
dimensional finite element models are developed for a bridges prior to its testing. The results from
these dynamic analyses are used to select instrument positions on the bridge and predict static
displacement. Then, they are calibrated using the experimental frequencies and mode shapes. The
frequencies and mode shapes mainly are used to provide a basis for the study of the influence of
certain parameters on the dynamic response of the structure the influence of secondary structural
elements the cracking of the deck slabs the effects of long-term concrete creep and shrinkage and
soon (Paultre and Proulx, 1995). Besides more sophisticated methods based on finite element or
finite strip representation have been used by some researchers to study the dynamic behaviour of
bridges Fam (1973) and Tabba(1972) studied the behaviour of curved box section bridges using the
finite element method for applied static and dynamic loads. A three-dimensional finite element
analysis program was developed for curved cellular structures. Solutions of several problems
involving static and dynamic responses were presented using the proposed and others sophisticated
methods of analysis. In this report a beam is analysed using FEM.
Element Used In Member ANSYS 2012
Element which are used in this report are:
Solid 65 For concrete
Link 8 For Rebar
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Finite element model of concrete SOLID65 Description:
SOLID65 is used for the 3-D modeling of solids with or without
reinforcing bars (rebar). The solid is capable of cracking in tension and crushing in
compression. In concrete applications, for example, the solid capability of the element may be
used to model the concrete while the rebar capability is available for modeling reinforcement
behavior. Other cases for which the element is also applicable would be reinforced composites (such
as fiberglass), and geological materials (such as rock). The element is defined by eight nodes having
three degrees of freedom at each node: translations in the nodal x, y, and z directions. Up to three
different rebar specifications may be defined. The concrete element is similar to the SOLID45 (3-D
Structural Solid) element with the addition of special cracking and crushing capabilities. The most
important aspect of this element is the treatment of nonlinear material properties. The concrete is
capable of cracking (in three orthogonal directions), crushing, plastic deformation, and creep. The
rebar are capable of tension and compression, but not shear. They are also capable of plastic
deformation and creep.
Figure 21 Solid 65 Geometry
SOLID65
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Input Summary
Nodes:-I, J, K, L, M, N, O, P
Degrees of Freedom:-UX, UY, UZ
Real Constants:-MAT1, VR1, THETA1, PHI1, MAT2, VR2, THETA2, PHI2, MAT3, VR3,
THETA3, PHI3, CSTIF
(where MAT n is material number, VR n is volume ratio, and THET A n and PH In are orientation
angles for up to 3 rebar materials)
Material Properties
EX, ALPX (or CTEX or THSX), DENS (for each rebar) EX, ALPX (or CTEX or THSX), PRXY
or NUXY, DENS (for concrete)
Supply DAMP only once for the element (use MAT command to assign material property set).
REFT may be supplied once for the element, or may be assigned on a per rebar basis
Special Features
Plasticity Creep
Cracking Crushing
Large deflection Large strain
Stress stiffening Birth and death
Adaptive descent
LINK8 Description:
LINK8 is a spar which may be used in a variety of engineering applications. This element
can be used to model trusses, sagging cables, links, springs, etc. The 3-D spar element is a uniaxial
tension-compression element with three degrees of freedom at each node: translations in the nodal x,
y, and z directions. As in a pin-jointed structure, no bending of the element is considered. Plasticity,
creep, swelling, stress stiffening, and large deflection capabilities are included.
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Figure 22 LINK8 GEOMETRY
LINK8 Input Summary
Nodes:-I, J
Degrees of Freedom:-UX, UY, UZ
Real Constants:- REA - Cross-sectional area ISTRN - Initial strain
Material Properties EX, ALPX (or CTEX or THSX), DENS, DAMP
Special Features
Large deflection ,Creep, Large deflection, Plasticity, Stress stiffening, Swelling , Birth and death
ANSYS MODEL
General
Element Types
Table: 1.2- Material Type
The element types for this model are shown in Table 3.1. The Solid65 element was used to
model the concrete. This element has eight nodes with three degrees of freedom at each node –
translations in the nodal x, y, and z directions. This element is capable of plastic deformation, cracking
in three orthogonal directions, and crushing.
A Solid45 element was used for steel plates at the supports for the beam. This element has
eight nodes with three degrees of freedom at each node – translations in the nodal x, y, and z directions.
Material Type ANSYS Element
Concrete Solid 65
Steel Plates and Supports Solid 45
Reinforcement Link 8
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A Link8 element was used to model steel reinforcement. This element is a 3D spar element
and it has two nodes with three degrees of freedom – translations in the nodal x, y, and z directions.
This element is also capable of plastic deformation.
Real Constants
The real constants for this model are shown in Table: 1.3. Note that individual elements
contain different real constants. No real constant set exists for the Solid45 element. Real Constant Set
1 is used for the Solid65 element. It requires real constants for rebar assuming a smeared model.
Values can be entered for Material Number, Volume Ratio, and Orientation Angles. The material
number refers to the type of material for the reinforcement. The volume ratio refers to the ratio of
steel to concrete in the element. The orientation angles refer to the orientation of the reinforcement in
the smeared model. ANSYS allows the user to enter three rebar materials in the concrete.
Each material corresponds to x, y, and z directions in the element. The reinforcement has
uniaxial stiffness and the directional orientation is defined by the user. In the present study the beam
is modelled using discrete reinforcement.
Therefore, a value of zero was entered for all real constants which turned the smeared
reinforcement capability of the Solid65 element off. Real Constant Sets 2 is defined for the Link8
element. Values for cross-sectional area and initial strain were entered.
Table: 1.3- Real Constants
Real Constant Element Type Constants
Real
Constants
for Rebar
1
Real
Constants
for Rebar
2
Real
Constants
for Rebar
3
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3.2.1 Material Properties
Three material models were given:
1. Material 1 for Concrete
a. Linear Isotropic
b. Concrete
c. Multi linear Elastic
2. Material 2 for Steel Plates
a. Linear Isotropic
3. Material 3 for FRP
a. Linear Isotropic
b. Bilinear Isotropic
1.
Solid 65
Material
Number
0 0 0
Volume
Ratio
0 0 0
Orientation
Angle
0 0 0
Orientation
Angle
0 0 0
2.
Link 8
Cross-
sectional
Area
(mm2)
50.26
Initial
Strain
(mm/mm)
0.0088874
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The values of Material Properties is shown in Table 3.3
Table: 1.4- Material Properties
Material Model No. Element Type Material Properties
1.
Solid 65
Linear Isotropic
EX 38,480
PRXY 0.2
Multi linear Isotropic
Strain Stress
Point 1 0.00036 9.8023
Point 2 0.0006 15.396
Point 3 0.0013 27.517
Point 4 0.0019 32.102
Point 5 0.00243 33.095
Concrete
ShrCf-Op 0.3
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ShrCf-Cl 1
UnTensSt 5.3872
UnTensSt -1
BiCompSt 0
HydroPrs 0
BiCompSt 0
UnTensSt 0
TenCrFac 0
Linear Isotropic
2. Solid 45 EX 2,00,000
PRXY 0.3
Linear Isotropic
EX 1,87,000
PRXY 0.65
3. Link 8 Bilinear Isotropic
Yield Stress 2050
Tang Mod 0.65
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Fig: 7. Stress- Strain Curve of Concrete
Numbering Controls
The command merge items merges separate entities that have the same location. These
items will then be merged into single entities. Caution must be taken when merging entities in a
model that has already been meshed because the order in which merging occurs is significant.
Merging key points before nodes can result in some of the nodes becoming “orphaned”; that is, the
nodes lose their association with the solid model. The orphaned nodes can cause certain operations
(such as boundary condition transfers, surface load transfers, and so on) to fail. Care must be taken
to always merge in the order that the entities appear. All precautions were taken to ensure that
everything was merged in the proper order. Also, the lowest number was retained during merging.
Commands Used
NUMMRG,NODE – To merge all nodes
NUMMRG,KP – To merge all key points
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Boundary Conditions
Displacement boundary conditions are needed to constrain the model to get a unique solution.
To ensure that the model acts the same way as the experimental beam, boundary conditions need to
be applied at points of symmetry, and where the supports and loadings exist. The symmetry boundary
conditions were set first.
(Go To Main Menu)
Solution
Define Loads
Apply
Structural
Displacement
On Lines
(Pick lines) & OK
(Lab2) All DOF (DOFs to be constrained)
(Value) 0
OK
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3.2.6 Analysis Type
The finite element model for this analysis is a simple beam under transverse loading. For the
purposes of this model, the Static analysis type is utilized. The Restart command is utilized to restart
an analysis after the initial run or load step has been completed. The use of the restart option will be
detailed in the analysis portion of the discussion.
(Go To Main Menu)
Solution
Analysis Type
Static & OK
3.2.7 Load Step Method
Step 1
(Go To Main Menu)
Solution
Solution Controls
Basic – Enter the values as shown below.
Step 2
(Go To Main Menu)
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Solution
Solution Controls
Nonlinear - Enter the values as shown below.
Step 3
(Go To Main Menu)
Solution
Define Loads
Apply
Structural
Force/Moment Value
On Nodes
Step 4
(Go To Main Menu)
Solution
Load Step Opts
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Write LS File
(Value) Load Step file number n, 1 &OK
Step 5
(Go To Main Menu)
Solution
Define Loads
Delete
Structural
Force/Moment Value
On Nodes- Pick All
Step 6
Repeat the procedure from step 1 to step 5 with different load values.
Step 7
(Go To Main Menu)
Solution
Solve
From LS File
(Value) LSMIN- 1, LSMAX- 6, LSINC- 1
Step 8
(Go To Main Menu)
General Post Processor
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Read Results
By Pick- Read
Step 9
(Go To Main Menu)
Time History Processor
Add
Nodal Solution
DOF
Choose Y- Component Displacement
Pick middle node & OK
Plot graph
The model for the analysis now ready it is shown in fig.23 with simply supported on both ends with
a uniform distributed load of 14.4 kN/m in fig. 24 which we already worked out in our previous
chapter 4 and the max stress in the section is 149.9 N/mm2 with the max. Deflection of 12.2 mm.
Figure 23 Model Of ANSYS
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Figure 24 Model Showing 14.4 kN/m UDL with simply supported at both ends
During the analysis it gives the convergence graph for the nonlinear analysis for concrete and FRP shown in fig. 25.
Figure 25 Nonlinear analysis graph during analysis
14.4 kN/mm
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Figure 26 Stress along the length of the beam.
In figure 26 the stress along the length of the bar is shown. During the design we get stress in the reinforcement was 483.4 N/mm2 and during the analysis the max. stress is 479.9 N/mm2
Figure 27 Top stress in the beam
479.9823
479.9823
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 90 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
In fig. 28 the max. deflection in the beam is shown which is 12.03 mm and according to our calculation the long term deflection was 12.2 mm
Figure 28 Deflection in the beam
The analysis show the time dependent results occur due to loading and crack pattern in the section. In fig 29 it shows the first crack and in fig. 30 it show the final cracks present in the beam.
Figure 29 Initial crack in the beam Figure 30 Final crack of the beam
Deflection = 12.02 mm
My = 12.02
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 91 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Chapter 7 Costing
FRP bars are two to three times higher than conventional material but an FRP composite element or
structure can be cost competitive only if the total life time is assessed. On a per kilogram basis FRP
composites are more expensive than traditional construction materials. For a realistic cost
comparison other factors should be included less material is required because
• Higher specific strength
• Fabrication costs are lower
• Lower transportation
• Erection costs are generally lower
for structures made of FRP composites in most cases life of the composite structures will be longer
than that made of traditional materials and will require less maintenance during its life span.
Since it is a non-corrosive material so the maintenance cost is very less and to this we can use his
section the:
• Bridge deck.
• Diaphragm wall
• Footing sections
• Beams
The transportation cost and maintenance cost are very less because of its less weight which can be
loaded and transported more in a truck as compared to conventional material.
INTRODUCTION
FRP has some excellent properties as a structural material. Its application to bridges offers a
possibility to solve problems that bridges made of conventional materials are facing today such as
corrosion and damages incurred early in the life-cycle of a structure. Presently, FRP’s unit price
is usually rather more expensive than that of other conventional materials. This may increase
the initial cost of the FRP superstructure and is one of the obstacles deterring widespread use of
the material in FRP bridges.
In order to evaluate the benefit of using FRP in bridges, it is important to consider FRP’s life
cycle cost (LCC) including the cost for maintenance. There has been some research1)-3) on the
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 92 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
cost benefit of FRP structures; however, because some of those studies begin with the design of
the structures and include many suppositions, the LCC estimates of FRP structures are not so
reliable.
With this in mind, the authors tried to evaluate the LCC of an actual FRP footbridge, remaining as
faithful to actual conditions as possible. The case study is based on an FRP footbridge constructed
in Okinawa, Japan, in 2000. It is called “Okinawa Road Park Bridge” and is pictured in Figure .
View of the Okinawa Road Park Bridge
THE STRUCTURES FOR THE CASE STUDY
A FRP footbridge and PC footbridge crossing a 4-lane road were considered as the case models.
The bridges are located close to the seashore and severely affected by sea salt.
The main girders of the FRP footbridge are made of hand lay-up FRP; pultruded FRP is used for
the stiffeners, decks, and floor systems. Both types of FRP were made of glass fiber and vinylester
resin. Parts of the FRP footbridge were made in several factories within the Tokyo area, assembled
in a factory in Tokyo Bay, and then shipped to Okinawa.
Wall type piers and steel pipe pile foundations were used in the substructure for both bridges.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 93 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Model cases of FRP and PC bridges
FRP bridges PC bridges
Concept Two span girder bridge
with GFRP C-girders
Single span deck girder bridge
with hollow post-tension concrete
beams
Length 37.8m 36.0m
Span 19.7m+17.2m 35.0m
Width 4.3m 4.3m
Live load 350kgf/m2 for main girders
500kgf/m2 for decks
CALCULATION METHOD OF LCC
Direct construction costs of the initial cost and the maintenance cost for both FRP and PC bridges
were calculated based on the design reports for both bridges. LCC was obtained by the equations:
LFRP bri. = IFRP bri. + MFRP bri.
LPC bri. = IPC bri.. + MPC bri.
L: Life-cycle cost
I: Initial cost
M: Maintenance cost
We did not calculate the cost for disuse neither did we consider the discount rate to discount future
costs to the base year. Initial costs were calculated for both the superstructure and substructure.
Maintenance costs were calculated only for the superstructure. The authors tried to set realistic
suppositions in situations where no data existed. In this study, the authors made some assumptions
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 94 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
for unknown conditions and simplified the calculation. Hence the values of the costs in this study
do not indicate the real values of the Okinawa Road Park Bridge itself.
RESULTS
Initial costs
PC footbridges
Five types of superstructure were roughly designed for the PC footbridges. A deck girder
footbridge with hollow post-tension concrete beams was selected after considering multiple
viewpoints, including economy, workability, structure, view, and maintenance. Table 2 shows the
model cases of the PC footbridge. CASE-1 is the base case with two types of corrosive protected
cases added. CASE-2 adopts epoxy resin coated reinforcing bar and PC tendon. CASE-3 also
adopts coated bar and tendon, with the addition of a paint coating on the concrete surface. The
calculated the initial cost of each superstructure is: 48,240,000JPY, 50,620,000JPY and
54,370,000JPY respectively. As regards the substructure, two piers (Pier 1 and Pier 2) were roughly
designed for each of three alternatives. The best results are shown in Table 2. The total cost of the
substructure was 10,130,000JPY.
FRP footbridges
The initial cost of FRP bridges is roughly divided into three categories: (1) materials, (2) assembly,
and (3) mold for hand lay-up. Table 3 shows the initial cost of FRP bridges. The initial cost of the
FRP superstructure was 73,600,000JPY. The base model case (CASE-4) of the FRP footbridge has
some special points, for example, it is the first real FRP footbridge in Japan and it is located on
the seashore, suggesting that it may be possible to reduce its initial cost. The authors considered a
modified case (CASE-5) for FRP bridges so as to reduce its initial cost. These modifications were:
(1) change of handrail to aluminum, (2) change of design in the joint part of main girders, and
(3) sharing of mold by two bridges. The result of the modified initial cost became 62,350,000JPY.
Girish Kumar Singh, SPA/NS/BEM/615 Semester II, BEM, SPA, New Delhi 95 | P a g e
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Table 2: Model cases of PC bridges and initial costs (Unit: 1000JPY)
CASE-1 CASE-2 CASE-3
Corrosion
protection for the
None Coated
reinforcing bars
C d PC
Coated reinforcing
bars Coated PC
tendon
Initial cost for the
48,240 50,620 54,370
Substructure system Pier 1: 6 Steel pipe piles (φ600mm-9mm,
L=17.5m) Pier 2: 4 Steel pipe piles (φ600mm-
Initial cost for the
10,130
Total Initial costs 58,370 60,750 64,500
Table 3: Model cases of FRP bridges and initial costs (Unit: 1000JPY)
CASE-4 CASE-5
Modified points for the
superstructure
Standard FRP bridge based on
the real bridge
Aluminum handrail
Change of joint parts of the main
girders
Sharing the mold by 2 bridges
Initial cost for the
superstructure
73,600 62,350
Substructure system
Pier 1: 2 Steel pipe piles (φ500mm-9mm, L=15.0m)
Pier 2: 4 Steel pipe piles (φ500mm-9mm, L=18.0m) Pier 3: 2
Steel pipe piles (φ500mm-9mm, L=12.0m)
Initial cost for the
substructure
6,910
Total Initial costs 80,510 69,260
There are three piers (Pier 1, Pier 2, and Pier 3) for the substructure of the FRP footbridge. When
comparing the two pile systems, driven steel pipe piles and PHC (Pretensioned Spun High Strength
Concrete) piles with installation by inner excavation, the steel pipe piles substructure showed better results
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
in this case.
Comparing the total costs including both the superstructure and substructure, the difference of the initial
cost of the modified FRP footbridge (69,260,000JPY) was only 10% higher than the initial cost of the
corrosion protected PC footbridge. This result suggests FRP bridges have significant competitive power
even when considering the initial cost.
Maintenance costs
PC footbridge
Inspection and repair are the main maintenance considerations for bridges. Only the costs for repair were
considered in this study. The costs for inspection were omitted because it seems there are not large
differences in the inspection of PC and FRP bridges.
For the PC bridges, the authors estimated the penetration of chloride ion into the concrete after the
construction, and the repair was set when the concentration of chloride ion at steel reinforcing bars reached
1.2 kg/m3. Replacement of covering concrete and surface coating was selected as the repair method for
the PC bridges. The life of the surface coating which protects against chloride ion penetration was set
at 15 years and 30 years, and repair of the surface coating was calculated in these intervals. Table 4
shows the results of the repair costs.
FRP footbridge
Since the Okinawa Road Park Bridge is relatively new, there is not enough information on its repair and
maintenance requirements. However, five years after its construction, stainless steel bolts were replaced
because of corrosion due to the severely corrosive environment. This amounted to 1,000,000JPY. We
therefore considered the same scale of repair may be required at the same interval within a severely
corrosive environment and set the repair
cost for an FRP footbridge at 1,000,000JPY at 5-year intervals. In the modified case of FRP footbridges,
the repair cost was also modified by adopting highly durable bolts. The cost is 3,500,000JPY and the
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
repair interval was set at 40 to 50 years.
Repainting is the major repair concern for FRP footbridges. There will be no corrosion for FRP structures
caused by weak points of painting such as edges or bolt parts like a painted steel structure because
FRP does not corrode. Hence, we set the repainting interval based on the decrease of thickness caused
by the deterioration of the painting material. The repainting interval was set at about 120 years based
on the thickness (75 m) and the material (fluorine resin paint) of the paint. The repainting cost was
calculated and the result was 5,600,000JPY including the scaffolding for repainting.
LCC
Table 4 shows the results of initial cost, maintenance cost and LCC for both PC and FRP footbridges. At
50 years, LCC of the FRP footbridge was 90,510,000JPY; this is lower than the 50-year LCC of the
PC footbridge without corrosion protection. The lowest 50-year LCC was that of the PC footbridge with
epoxy resin coated reinforcing bar and PC tendon (CASE-2). However, the modified FRP footbridge
(CASE-5) showed the lowest 100-year LCC among our five cases. These results suggest that FRP
footbridges are more efficient when longer life is required in severely corrosive environments.
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Table 4: LCC results of both PC and FRP footbridges (Unit: 1000JPY)
CASE-1
CASE-2
CASE-3
CASE-4
CASE-5
Repair interval:
15 years
Repair interval:
30 years
Initial cost for
t t
48,240 50,620 54,370 73,600 62,350
Initial cost for substructures 10,130 10,130 10,130 6,910 6,910
Total the initial costs 58,370 60,750 64,500 80,510 69,260
Maintenance cost for 30
24,500 0 18,000 9,000 6,000 3,500
Maintenance cost for 50
42,500 0 27,000 9,000 10,000 3,500
Maintenance cost for 100
years
69,500 24,500 54,000 27,000 20,000 7,000
50 years LCC 100,870 60,750 91,500 73,500 90,510 72,760
100 years LCC 127,870 85,250 118,500 91,500 100,510 76,260
CONCLUSION
The result suggests that FRP bridges has a competitive edge over other types of construction in spite
of its initial cost and that FRP footbridges are more efficient when longer life is required in severely
corrosive environments.
The results from the FEM analysis are near to our manual design result so it can be concluded that the
section made up of FRP will behave like the model made in the ANSYS apart from the fire FRP is the best
option for the design consideration and can be used in non-compressive member, more research is needed
on the issues related to the fire susceptibility of the FRP in case of fire.
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
On the cost part if we are considering the total life of the section is far more than Steel so the section made
with the frp can resist more load and very less maintenance is required to that section so the proper
environmental situation have to kept in consideration during LCC it can increase in the initial cost of the
project but if we are considering the total life of the section then it will cost bit lesser than steel.
Since FRP can resist three times more load that steel so we required less FRP in the section that also be
considered during the cost analysis.
Furthermore research needed to support the fact that FRP can be used in buildings where fire is a problem
and to improve its quality against fire.
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
Chapter 8 Summery
This report give introduction of the FRP product, its manufacture process by the forming process,
advantages and disadvantages, limitations Material properties like corrosion, high strength, lightweight,
stability, finishes, design flexibility, thermal conductivity, and some of the physical properties like
density, coefficient of thermal expansion, some mechanical properties like tensile behavior
compressive behavior, shear behavior and effect of temperature on FRP bars etc.
It also include the chemical properties and its application in various form like sheet, tube, cover, beam,
slab, tanks, blades, strengthen the system also some of its marine application as well as some form of
pipe, piles, also in the aeronautics industry. The introduction of FRP bars is also given to give an idea
about the form of bars and its limitation and advantage over steel is also described in detail.
Various code used in the design, experiment and analysis is listed. Some of the codes are used just for
the detailing of the FRP beam and some of the codes are for the testing which is also tabulated inside
the report.
This report have a manual design problem is explained with all the design procedure as per ACI440.04r
and all the tables and equations references are given which are explained in the code. The design
problem is A simply supported, normal weight concrete beam with fc’ = 27.6 MPa is needed in a facility
to support a machine. The beam is an interior beam. The beam is to be designed to carry a service load
of wLL =5.8 kN/m an a superimposed service load wSDL =3.0 kN/m over a span of l =3.35m and the
result of the manual design is also listed at the end of the report.
FRP reinforced beam is analyzed using Finite Element Analysis the same section that we design in
the previous chapter is analyzed and result of that section are compared to give a relevant theory
about its behavior.
Costing of the FRP method of analysis of its cost as well as an example of LCC is also covered.
Study of Fiber Reinforced Polymer Materials in Reinforced concrete Structures As Reinforced bar
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