THEORETICAL BEHAVIOR OF COMPOSITE CONSTRUCTION PRECAST REACTIVE POWDER RC GIRDER AND ORDINARY RC DECK SLAB

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International Journal of Civil Engineering and Technology (IJCIET)

Volume 6, Issue 12, Dec 2015, pp. 08-21, Article ID: IJCIET_06_12_002

Available online at

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ISSN Print: 0976-6308 and ISSN Online: 0976-6316

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___________________________________________________________________________

THEORETICAL BEHAVIOR OF

COMPOSITE CONSTRUCTION PRECAST

REACTIVE POWDER RC GIRDER AND

ORDINARY RC DECK SLAB

Dr. Nameer A. Alwash, and Ms. Dunia A. Abd Al-Radha

College of Engineering, Babylon University, Iraq

ABSTRACT

This study displays numerically (or theoretically) investigation by using

the finite element models for experimental work of composite behavior for

hybrid reinforced concrete slab on girder from locale material in Iraq,

ordinary concrete in slab and reactive powder concrete in girder, RPC, with

steel fibers of different types (straight, hook, and mix between its), tested as

simply supported span subjected under two point loading. Which ANSYS

version 15.0 is utilized. By studying the compatibility between the

experimental results and the theoretical results. As well as, parametric study

of many others variables are investigated by using ANSYS (version 15.0), such as: changing the compressive strength of the slab, changing the main

reinforcement of the girder, and changing thickness of resin bond layer

between girder and slab. The results showed that the increasing of the grade

of slab concrete from 25.8 MPa to (45, 55, 158)MPa the ultimate capacity

increases by (7.5, 14.2, and 24.5) % and the deflection decreases to (10.6,

16.4, and 24.8)% for reinforced hybrid RPC girder with NC slab.

Also, the results indicated that the increase of the area of tension

reinforcement in the girder of the considered section, by (33.3) %, improves

the stiffness behavior and the ultimate capacity by 19.7%. Which the results

confirmed that the degree of improvement of the both parameters :(grade of

slab concrete and area of tension reinforcement bars of the girder) on hybrid

reinforced girder is much larger than for same specimen without shear

reinforcement (using epoxy adhesive). Since the improvement in the ultimate

load of the considered specimen without shear reinforcement does not exceed

5%; however, the bond-slip decreases to 18.4%; and the deflection decreases

to 32.6%, when compressive strength of the slab increases from (25.8 to 158)

MPa. In addition, There is an optimum epoxy layer thickness that give the best

behavior and strength and it is 4mm for the considered specimens in the

present study.

Theoretical Behavior of Composite Construction Precast Reactive Powder RC Girder and

Ordinary RC Deck Slab


Key words: ANSYS Analysis, Area of Tension Reinforcement, Bond-Slip,

Compressive Strength, Reactive Powder Concrete, RPC, Resin Bond Layer,

Hybrid Concrete, Composite Section, RC Girder, RC Slab, Shear Connecters,

Inverted T Section.

Cite this Article: Dr. Nameer A. Alwash, and Ms. Dunia A. Abd Al-Radha.

Theoretical Behavior of Composite Construction Precast Reactive Powder RC

Girder and Ordinary RC Deck Slab. International Journal of Civil

Engineering and Technology, 6(12), 2015, pp. 08-21.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=6&IType=12

1. INTRODUCTION

Research over the past decade has yielded a new classification of concrete called

Reactive Powder Concrete, RPC, now labeled and classified as Ultra-High

Performance Concrete, UHPC. The term UHPC is used for defining concretes that are

produced by carefully selected high quality components, optimized blend designs,

which are batched, mixed, placed, consolidated and cured to the highest industry

standards.

Forster, 1994 [1] defined UHPC as "a concrete made with appropriate materials

combined according to a selected mix design and properly mixed, transported, placed,

consolidated, and cured so that the resulting concrete will give excellent performance

in the structure in which it will be exposed, and with the loads to which it will be

subjected for its design life". While American Concrete Institute had defined UHPC

as “Concrete meeting special combinations of performance and uniformity

requirements that cannot always be achieved routinely using conventional

constituents and normal mixing, placing and curing practices” [2]. These requirements

may involve enhancements of characteristics such as placement and compaction

without segregation, long-term mechanical properties, early-age strength, volume

stability, or service life in severe environments. UHPC (or RPC) technology

contributes significantly to the realization of sustainable development. The technology

carries an equation that sums up ‘sustainable construction’ in that it provides for a

minimum impact on the environment, maximizes structural performance and provides

a minimum total life-cycle cost solution. RPC is a cold cast cementitious material in

which the mechanical properties of the composite matrix are improved. This material

is very high strength and ductile. Its more isotropic nature and greater ductility make

it. All these improvements, however, result in a substantial cost increase over

conventional and even high-performance concrete. Because of its cost, RPC will not

replace concrete in applications where conventional mixes can economically meet the

performance criteria. However, with some of its performances nearing those of metals

and at a minor cost compared to steel, RPC becomes truly competitive in areas where

steel is predominant. To increase the load carrying requirement of steel sections, a

hybrid section is used. The concept of hybrid section in steel structures is not a new

idea. In 1990, Salmon, C. G., and Johnson, J. E. [3] defined a hybrid girder as one that

has either the tension flange or both flanges of steel section made with a higher

strength grade of steel than used for the web.

2. LITERATURE REVIEW

A brief of some research related to this study, are presented, as:

Aziz, 2006 [4] studied the experimental and theoretical flexure and shear behavior of

simply supported seventeen hybrid concrete I- beam under two-points load, with and



without construction joints by epoxy layer, the hybrid section was from conventional

and high strength concrete distributed on upper flange- web – lower flange for two

groups. Also, ANSYS program was used to test and compare with the experimental

results. The construction joints were modeled by using three dimensional surface-to-

surface contact (Interface) elements connected with concrete elements at shared nodes

represented the adhesion epoxy layer, and using a nonlinear spring element

(COMBIN-39) to represented the dowel action of the transversely crossing bars in

ANSYS program. The results indicated that for two-construction joint beams, no

interface slip was recorded at the joints between tension flanges and web. Also, the

tested beams that had one-construction joint had exhibited an increase in ductility

between (4% - 8%). While the tested beams that had two-construction joints had

exhibited an increase in ductility between (6% - 62%). Resan, 2012 [5] investigated

the experimental and theoretical flexure behavior of simply supported sixteen

composite beams, from ferrocement slab and aluminum beam (I- section and box)

connected together by adhesive epoxy layer, under static load subjected to 3-point

loading, as described in fig. (1 and 2). ANSYS program was used to test and compare

with the experimental results. Different models with different interface element types

(linear spring element COMPIN14, nonlinear spring element COMPIN39, cohesive

zone interface element INTER205, and a solid shell element of SOLSH190) were

used to simulate the adhesive epoxy layer. Model COMPIN14 spring element gave

closer results to experimental ones as well as less solution iterations and so less

solution time in ANSYS program. The results reveal that the proposed beams have a

good loading capacity relative to their weight, by the assistance of using the epoxy

which was provided adequate bond that could be perfect as the slip between the slab

and beam remain very small during the test.

Figure 1 Details of the composite beams tested by Resan [5].

Figure 2 Aluminum sections details that used in the composite beams tested by Resan

[5].

Al-Amry, 2013 [6] studied the experimental and theoretical shear behavior of nine

reinforced concrete deep beams made of hybrid concrete: Normal strength concrete

(NSC) in tension zone and high strength concrete (HSC) in compression zone, under

effect of two point static loads . One of them was tested as pilot and eight beams were

divided into two groups (A and B, as described in fig. 3. Also ANSYS program was

used to test and compare with the experimental results. The construction joints were

modeled by using nonlinear node-to-node interface element Contac 52 that




represented for (with and without dowel action) in ANSYS program. The variables

parametric were: the effects of: (HSC) layer thickness, presence of web reinforcement

and method of casting (monolithically or at different times). The results were

indicated that the hybrid beams which cast monolithically, were exhibited an increase

in ductility about (13.3- 22.6) % and (17.3- 26.3) % for specimens without and with

web reinforcement, respectively. While, the hybrid beams with construction joint and

epoxy layer of thickness about (1 mm), exhibited larger increasing in ductility about

(28.7%) and (30.2%) for specimens with and without web reinforcement, respectively

when compared by control beam.

Group A) without web reinforcement

(Group B) with web reinforcement

Figure 3 Details of tested hybrid beams by Al-Amry [6].

Ismael, 2013 [7] investigated the experimental and theoretical flexural behavior of

fifteen monolithic RPC T-beams. The variables parametric were: the effects of steel

fiber volumetric ratio, silica fume ratio, tensile steel ratio, hybrid section and flange

width. And for hybrid section, no construction joint was submitted because there was

no time delayed between casting of the two materials. Also ANSYS program was

used to test and compare with the experimental results. No Interface element was

taken in ANSYS program, Its considered to be full bond between the material

changing. The results were indicated that using RPC in web and normal concrete in

flange effectively enhances the performance of T- beams in comparison with normal

concrete T-beams.

3. EXPERIMENTAL PREPARATIONS

3.1. Concrete Mix Design

1. Reactive powder concrete: To product RPC with maximum strength by using local

materials, it have been experimented tried mixes and chosen, which mixed [8] as

shown in TABLE I. For 3 mixes that the only variable is (the type and ratio) of steel

fiber.

2. Conventional concrete, CC: Normal weight concrete was used to cast all slabs and

one girder. It was decided to choose a mix of 1:1.5:3 (by volume) cement, sand,

gravel respectively and 0. 48 water cement ratio.

All girders were cured by smearing in a container filled with tap water heated at

rate (20Co per hour) until reached 60C

o to avoid heat shock, and the temperature



remained constant at 60Cofor 2 days and the container was covered with polyethylene

sheets, then the heat was gradually decreased to avoid heat shock, down to 20Co until

the age reached 28days [9].

TABLE I Mix Proportions

Mix Cement

Type

Cement

(Kg/m3)

Micro

silica

(Kg/

m3)

Sand

(Kg/

m3)

Super

plasticizer

(by wt. of

Cementetious)%

Water/cementetious

(cement +silica)

ratio

steel fiber

type and

ratio

Mix I Al-

Mass 960 240 1000

5%

58.9 Kg/ m3 0.175

2%

straight

Mix II Same same Same same Same same 2% hook

Mix III same Same same Same same Same

1%

straight+

1% hook

Mix IV same Same same Same same Same 0%

3.2. Material Properties

Materials that used to product RPC and normal concrete, as described below:

Cement: Ordinary Portland cement, Al-Mass, Locally-selected, complies ASTM

C150 [10].

Fine aggregate: Locally-selected, very fine sand, rounded particle and smooth

textures. And for RPC with maximum size 600μm complies ASTM C33-03 limits

[11].

Coarse aggregate: The max size was 10mm, Locally-selected, complies ASTM C33

[12].

Water: Tap water was used for both making and curing.

Steel Reinforcing Bars: deformed bars, deformation pattern C consists of diagonal

ribs inclined at an angle of 60 degrees with respect to the axis of the bar), with

properties as shown in TABLE II.

Epoxy Adhesive: Sikadur®-32 was used in this work for the bonding the old concrete

(girder) (28 days after casting) and the new (slab) as 3mm thickness layer [13].

Admixtures: 1) Super plasticizer: for the production of RPC, high water reducing

agent HWRA, Sika Viscocrete-4100[14], was used in this work, complies with

ASTM C494[15].

3. Micro Silica Fume: from LEYDE manufactory company, according to ASTM C1240

[16].

4. Steel Fibers: two types of fibers were used in this work as described in TABLES III,

IV.

TABLE II Material Properties for Steel Reinforcement

Properties for Grade400 for ASTM A 615/A

615M – 04b [12]

Diameter

12mm

Diameter

8mm

Yield stress, MPa

Min required :400MPa 644 603

Ultimate strength, MPa, Min required:600MPa 812 895

Longitudinal,% ,Min required: 9% 12.6 13.2




TABLE III Properties of the steel fibers,

with ACI 544.1R-96[17], ASTM A820[18]

Fiber type Hook ends

Density kg/m3 7800

Tensile strength,

MPa

1800

Length, mm 25

Diameter, mm 0.3 rounded section

Aspect ratio 83

The min tensile yield strength is (345 MPa)

TABLE IV Properties of the steel fibers manufactured by the Ganzhou

Daye Metallic Fibres Co., Ltd, China

Fiber type Straight, WSF 0213,

rounded section, Brass coated

Density kg/m3 7860

Tensile strength, MPa 2300

Length, mm 13

Diameter, mm 0.2mm±0.05mm

Aspect ratio 65

3.3. Description of Experimential Tested Beams

In this study, twelve RC sections (slab that cast after 31 days from girder casting)

were made and tested up to failure under static load. As shown in Fig.4 and TABLE V

the details of the sections, and the main parametric of this work.

Figure 4 Reinforcement details for Specimens.



TABLE V

Group 1 Change steel fiber ratio, and type

Type of steel

fiber

Concrete in

section

Type of shear

connection

Shear span over

effect depth

(a/d)

Girder

shape

S1 Mix I RPC in girder Stirrups Φ8@100 3.3 Rect.

S2 Mix II

S3 Mix III

S4 Mix IV

Group 2 Changing type of concrete in section

S5 Mix I Normal in all

sections Stirrups Φ8@100 3.3 Rect.

S1 RPC in girder

S6 RPC @h/2

in girder from the

bottom

Group3 Type of shear connection


S7 Epoxy only (no shear

stirrups

S8 Stirrups Φ8@50

S9 Stirrups Φ8@50 in

shear zones, and

Epoxy@ flexure zone

Group 4 changing Shear span over effective depth (a/d)


S10 4.3

S11 2.3

Group5 changing girder shape

S1 Mix I RPC in girder Stirrups Φ8@100 Rectangular

S12 Inverted T-

section

4. MODELING

In ANSYS program version 15.0, all materials of the specimens as concrete and steel

are modeled as nodes and elements. Solid element (CONCRETE 65) is used to

represent the concrete for both RPC and ordinary concrete but with different material

properties and input data. SOLID 185 is used to represent the steel plates at support

and loading points. LINK 180 is used to model the steel reinforcement in the girder

and the slab as discrete representation but with different material properties according

to its diameter (Φ8, Φ12), distributed according to the specimens. A perfect bond is

assumed between concrete and steel reinforcement. To represent the construction

joint, COMBIN 39 is used to represent the connection layer between the slab and

girder as discrete representation with using SURFACE-TO-SURFACE contact

elements. Also to represent the construction joint, CONTAC 178 is used as another

model. but the results of model (COMBIN 39 with SURFACE-TO-SURFACE

contacts elements) is more close to the experimental results, so this study depends

(COMBIN 39 with SURFACE-TO-SURFACE contacts elements) model. The finite

element models adopted in this study have a number of inputs values. These inputs

depend upon the experimental results and according to equations and assumptions of

the finite modeling, which can be classified as:




Concrete characteristics' values, indicated in table VI;

Steel characteristics' values, indicated in table VII;

Steel plates property, indicated in table VIII;

Interface characteristics' values, shown in table IX and X.

TABLE VI Concrete characteristics' values

Definition NSC RPC

Mix I Mix II Mix III Mix IV '

cf MPa(1) Uniaxial Crushing Stress 25.8 158 125.3 140.2 115.7

tf MPa(2) Uniaxial Cracking Stress 2.42 14.04 16.9 19.37 5.29

cbf MPa(3) Biaxial Crushing Stress 30.96 189.6 150.36 168.24 138.84 a

h MPa(4) Hydrostatic Pressure 47.44 273.66 217.3 242.834 200.398

1f , MPa(5) Hydro Biaxial Crush Stress

on,a

h

37.41 229.1 181.685 203.29 167.765

2f , MPa(6) Hydro uniaxial crush Stress

on, a

h

44.505 272.55 216.143 241.84 199.583

1 (6) Tension stiffening

parameters

6 6 6 6 6

0.6 0.9 0.6 0.6 0.6

o (7) Shear transfer Coefficient 0.55 0.55 0.55 0.55 0.55

c 0.66 0.66 0.66 0.66 0.66

cE MPa(8)

Young’s modulus of

elasticity

23523 45606 42836 44233 40448

(9) Poisson’s ratio 0.195 0.234 0.229 0.243 0.2084

(1), (2), (9), and (10) from experimental results.

(3), (4), (5) and (5) according to Willam and Warnke[19]

(7) and (8) from trial and error.

TABLE X Load-Displacement for Nonlinear Spring Element in Shear Direction.

Dia-meter Displa-cement, mm **

0 0

1 0.022

2 0.074

3 0.154

4 0.265

5 0.416

6 0.6244

7 0.925

8 1.416

9 2.597

9.419* 8.666

TABLE VII Steel Property Parameters

Diameter Steel Parameter

Ab, mm2 fy , MPa Es,MPa TE ,MPa Φ8 50.2655* 603* 200000** 6000** 0.3

Φ12 113.097* 644* 200000** 6000** 0.3

*Expermential results

** Aziz [4].

2



TABLE VIII Steel Plates Property

Steel Plate Parameter Value

Thickness of steel plates 15 mm

Modulus of elasticity, Es 200000 MPa

Tangent modulus of elasticity, ET 2000 MPa

Poisson’s ratio (υ) 0.3

Material behavior Linear elastic

TABLE IX Interface Property Parameters

Interface Parameter Definition value Note

μ Coefficient of friction 1.0 ACI-318 Code

τmax Maximum equivalent shear stress,

MPa

14.896 Xinzheng, and Jianjing

[20]

Target surface NSC as material 2

Contact surface RPC as material 1

FKN Contact compatibility factor 1.0 Assumed

Fdu Ultimate dowel force, kN 9.419 Aziz [4]

5. RESULTS OF FINITE ELEMENT ANALYSIS COMPARISON

WITH EXPERIMENTAL RESULT

The largest difference in the results is in the first cracking load of S4, about (16.67%).

The largest difference is in mid-span deflections at service load of S4 and S9 which is

about (19.2%) for both specimens.

The experimental and numerical slip (horizontal displacement) measurements

versus applied load for S7 are shown in Fig.5. In general, the load-slip curve from the

finite element analyses agree well with the experimental data with difference not more

than 12.2%.

Figure 5 Bond slip for S7

0

50

100

150

200

250

0 0.05 0.1 0.15 0.2 0.25

Ap

pli

ed L

oad

, kN

Relative horizontal displacement between slab and girder, mm

S7-slip-EXP

S7-slip-FEM




6. PARAMETRIC STUDY

The effect of some selected parameters on overall behavior of hybrid concrete,

reinforced RPC girder with reinforced NSC deck slab are decided herein, as follows:

6.1. Compressive strength for the slab

To study the effect of compressive strength of the slab on the flexural behavior of

hybrid reinforced concrete sections, four specimens were taken, with changing grade

of the concrete slab to (35, 45, and 65 as NSC, and 158 as RPC) MPa. From fig. 6 and

7, the results showed that the effect of the grade of slab concrete is more effective on

S1 than S7, which there are no significant difference in the stiffness behavior in S7

group- (fć of 45, 55, and 158) MPa since the improvement in ultimate load did not

exceed 5% when compressive strength increased from (25.8 to 158) MPa. While the

increase in ultimate load of S1 was rather noticeable which exceeded 20% when the

compressive strength of the slab developed from (25.8 to 158) MPa. Fig. 8 shows that

the bond-slip decreased for S7 by (2.7, 7.9, and 18.4)% when the compressive

strength of the slab developed from (25.8 to 158) MPa.

Figure 6 Load-Deflection Curves for fć effect of S1 by ANSYS.

Figure 7 Load-Deflection Curves for fć effect of S7 by ANSYS.

0

50

100

150

200

250

300

0 5 10 15 20

Applied

lo

ad,

kN

Mid span deflection, mm

S1-(fć=25.8) S1-(fć=45) S1-(fć=55) S1-(fć=156)

0

50

100

150

200

250

0 10 20 30

Applied

Lo

ad, kN


S7-(fć=25.8) S7-(fć=45) S7-(fć=55) S7-(fć=156)



Figure 8 Bond-Slip Curves for fć effect of S7 by ANSYS

Figure 9 load-deflection curves for studying Tensile Reinforcement effect for S1

using ANSYS

6.2. Tension reinforcement steel of the girder

To explain the effect of the tensile steel reinforcement area in girder on the behavior

of homogenous and reinforced hybrid cross section, two specimens were studied with

changing of tensile reinforcement area (4Φ10, and 4Φ16) for S1 and S7. Increasing

the tension reinforcement area of the girder improves the stiffness behavior and the

ultimate capacity. Fig. 9 and 10 indicate that the effect of increasing area of tension

reinforcement of the girder is more effective on improving the stiffness behavior of

S1 than S7; which when use Φ16 instead of Φ12, the improvement in ultimate load of

S1 and S7 is (19.7, and 4.1)%, respectively. The small effect of increasing tensile

reinforcement in the slab S7 may be attributed to the type of failure which is splitted

in connection between the slab and girder. Fig.11 shows that increasing the area of

tension reinforcement has no significant influence on bond-slip response for S7.

Figure 10 load-deflection curves for Studying Tensile Reinforcement Effect for S7

using ANSYS.

0

50

100

150

200

250

0 0.05 0.1 0.15 0.2

Applied

Lo

ad, kN

Bond-Slip, mm

S7-(fć=25.8)

S7-(fć=45)

S7-(fć=55)

S7-(fć=156)

0

50

100

150

200

250

300

0 5 10 15 20

Applied

lo

ad,

kN


S1-(4Φ12)

S1-(4Φ16)

S1-(4Φ10)

0

50

100

150

200

250

0 10 20 30

Applied

Lo

ad, kN


S7-(4Φ12) S7-(4Φ16) S7-(4Φ10)




Figure 11 Bond-Slip curves for changing Tensile Reinforcement of S7 using ANSYS.

6.3. Number of shear connectors and effect of epoxy resin layer.

To explain the effect of thickness of epoxy resin layer, five specimens were studied

on the behavior of hybrid reinforced cross section with no shear reinforcement S7, by

changing the epoxy resin thickness to (1.5, 4, 6 and 10) mm. From noticing fig. 11,

and 12, the results showed that when the thickness of epoxy resin layer increased

from 1.5mm to (3, 4, 6 ,and 10) mm, the load in early stages (elastic-uncracked)

increased about (63.6, 58.6, 73.5, and 111.7)%, respectively. For mid-span deflection

is equal to 1mm.However, fig. 13 shows that there is an optimum epoxy layer

thickness that give the best behavior and strength and it is 4mm, as also indicated in

fig. 13 and at elastic-cracked and post-cracking stages. In general, all results and fig.

14 indicate that stiffness behavior and bond- slip response of specimen with epoxy

thickness equals to 10 mm is acted as if it was 1.5mm thickness in post-cracking

stage. Also, the same figure indicated that the bond-slip response of specimens with

epoxy thickness equals to (3, 4, and 6)mm were similar at early loads stages. This was

due to the epoxy layer thickness, when it was near to be slight, it would be not

sufficient for the transfer of the stresses and strains from the slab to the girder. And as

thicker of the epoxy layer was applied as it would be appropriate to accommodate and

transferred the stresses and strains from the slab to the girder. But when the thickness

of epoxy layer became larger, the behavior of it acted close to be rigid layer and bond

slip was happening faster between the contact surfaces.

Figure 12 Load-Deflection curves for Epoxy Resin Layer Effect for S7 by using

ANSYS

0

50

100

150

200

0 0.05 0.1 0.15 0.2 0.25 A

pplied

Lo

ad, kN

Bond- Slip, mm

S7-(4Φ12)

S7-(4Φ16)

S7-(4Φ10)

0

50

100

150

200

250

0 10 20 30

Applied

Lo

ad, kN


S7-(t=1.5mm) S7-(t=3mm) S7-(t=4mm) S7-(t=6mm)



Figure 13 Bond-Slip curves for Epoxy Resin Layer Effect on specimen S7 by using

ANSYS

Figure 14 Bond-Slip curves for Epoxy Resin Layer Effect of S7 by using ANSYS.

7. CONCLUSION

There is reasonable agreement in the comparison between the experimental and the

numerical of all results with maximum difference not exceeds (14.7%).

From ANSYS results, the increasing of the grade of slab concrete from 25.8 MPa to

(45, 55, 158)MPa the ultimate capacity increases by (7.5, 14.2, and 24.5) % and the

deflection decreases to (10.6, 16.4, and 24.8)% for reinforced hybrid RPC girder with

NC slab.

From ANSYS results, the increase of the area of tension reinforcement in the girder

of the considered section, by (33.3) %, improves the ultimate capacity by 19.7%.

From ANSYS results, the degree of improvement of the both parameters :(1- grade of

slab concrete and 2- area of tension reinforcement bars of the girder) on hybrid

reinforced girder is much larger than for same specimen without shear reinforcement

(using epoxy adhesive). Since the improvement in the ultimate load of the considered

specimen without shear reinforcement does not exceed 5%; however, the bond-slip

decreases to 18.4%; and the deflection decreases to 32.6%, when compressive

strength of the slab increases from (25.8 to 158) MPa.

There is an optimum epoxy layer thickness that give the best behavior and strength

and it is 4mm for the considered specimens in the present study.

16.2 26.5 25.7

28.1 34.25

84.4 94.4

110.6 102

85.5

191.3 212.9

220.9 205.6

184.5

0

50

100

150

200

250

0 2 4 6 8 10 12

Applied

Lo

ad, kN

The Thickness Layer of Epoxy, mm

Mid. Defle.=1mm Mid. Defle.=6mm Mid. Defle.=20mm

0

50

100

150

200

250

0 0.05 0.1 0.15 0.2 0.25

Applied

Lo

ad, kN

Bond-Slip, mm

S7-(t=1.5mm) S7-(t=3mm) S7-(t=4mm) S7-(t=6mm)




REFERENCES

[1] Forster, S. W., "High-Performance Concrete Stretching the Paradigm ", Concrete

International, Oct, 1994, Vol. 16, No. 10, pp. 33-34.

[2] ACI Committee 318, Building Code Requirements for Reinforced Concrete (ACI

318-06) and Commentary-ACI318RM-06, American Concrete Institute, Detroit,

2006.

[3] Salmon, C. G., and Johnson, J. E., "Steel Structures: Design and Behavior", 3rd

Edition, Harper Collins Publishers Inc., USA 1990, (1086) p.

[4] Aziz, A. H. "Flexural And Shear Behavior Of Hybrid I-Beams With High-

Strength Concrete And Steel Fibers", Phd thesis, Univ. of Al-Mustansiriya, 2006.

[5] Resan, S. F., "Structural Behavior of Ferrocement- Aluminum Composite

Beams", Phd thesis, Univ. of Basrah, 2013.

[6] Al-Amry, M. Gh, "Experimental Investigation and Nonlinear Analysis of Hybrid

Reinforced Concrete Deep Beams" M.SC thesis, Univ. of Babylon, 2013.

[7] Ismael, M. A.," Flexural Behavior of Reactive Powder Concrete Tee Beams",

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