EXPERIMENTAL STUDY O F REINFORCED …...A total of two RC T-beams and One Rectangular beam were fabricated for this experimental program. Reinforced concrete T beam specimen of …

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 7, July 2017, pp.

Available online at http://www.iaeme.com/IJCIET/issues.

ISSN Print: 0976-6308 and ISSN Online: 0976

© IAEME Publication

EXPERIMENTAL STUDY O

CONCRETE CONTINUOUS

AND FLANGED BEAMS AT

Professor,

Kumaraguru College of Technology

Assistant Professor

Kumaraguru College of Technology

Assistant Professor (Sr.Gr.),

Sri Ramakrishna Institute of

ABSTRACT

Fiber-reinforced polymer (FRP) application is a very effective way to repair and

strengthen structures that have become structurally weak over their life span. FRP

repair systems provide an economically viable alternative to traditional repair

systems and materials. In this study Experimental and Analytical Investigation on

Behaviour of Reinforced concrete Continuous

strengthened using Glass Fiber Reinforced Polymer (GFRP) sheets are carried out.

Reinforced concrete T-beam

failure using a symmetrical two point static loading system. Two RC T

Rectangular beam were cast for this experimental test. One beam was used as a

control beam and one beams is strengthened u

(GFRP) sheets. Experimental data on load, deflection and failure modes of each of the

beams were obtained. The effect of different amount and configuration of GFRP on

ultimate load carrying capacity and failure mode of t

experimental results showed that the externally strengthened reinforced concrete

beam with bonded GFRP sheet showed significant increase in ultimate load

of comparative studies on deflection between T

made.

Key words: RC T-beams, Negative Moment region, GFRP sheets

IJCIET/index.asp 706 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) 2017, pp. 706–713, Article ID: IJCIET_08_07_076

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6308 and ISSN Online: 0976-6316

Scopus Indexed

EXPERIMENTAL STUDY OF REINFORCED

CONCRETE CONTINUOUS RECTANGULAR

AND FLANGED BEAMS AT SUPPORT REGION

Dr. P. Eswaramoorthi

Professor, Department of Civil Engineering,

Kumaraguru College of Technology, Coimbatore, Tamil Nadu

P. Sachin Prabhu

Professor, Department of Civil Engineering,

Kumaraguru College of Technology, Coimbatore, Tamil Nadu

P. Magudeaswaran

Professor (Sr.Gr.), Department of Civil Engineering,

Sri Ramakrishna Institute of Technology, Coimbatore, Tamil Nadu, India

reinforced polymer (FRP) application is a very effective way to repair and



materials. In this study Experimental and Analytical Investigation on

Behaviour of Reinforced concrete Continuous T-beams in Negative Moment Region


beam externally bonded with GFRP sheets were tested to

failure using a symmetrical two point static loading system. Two RC T-


control beam and one beams is strengthened using Glass Fiber Reinforced Polymer



ultimate load carrying capacity and failure mode of the beams were investigated.


beam with bonded GFRP sheet showed significant increase in ultimate load

of comparative studies on deflection between T-beam and Rectangular beam were

beams, Negative Moment region, GFRP sheets.

[email protected]

asp?JType=IJCIET&VType=8&IType=7

F REINFORCED

RECTANGULAR

SUPPORT REGION

Coimbatore, Tamil Nadu, India

Tamil Nadu, India

Department of Civil Engineering,

, Tamil Nadu, India

reinforced polymer (FRP) application is a very effective way to repair and



materials. In this study Experimental and Analytical Investigation on

beams in Negative Moment Region


externally bonded with GFRP sheets were tested to

-beams and One


sing Glass Fiber Reinforced Polymer



he beams were investigated. The


beam with bonded GFRP sheet showed significant increase in ultimate load.A series

beam and Rectangular beam were

Dr. P. Eswaramoorthi, P. Sachin Prabhu and P. Magudeaswaran

http://www.iaeme.com/IJCIET/index.asp 707 [email protected]

Cite this Article: Dr. P. Eswaramoorthi, P. Sachin Prabhu and P. Magudeaswaran.

Experimental Study of Reinforced Concrete Continuous Rectangular and Flanged

Beams at Support Region. International Journal of Civil Engineering and Technology,

8(7), 2017, pp. 706–713.

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1. INTRODUCTION

While many methods of strengthening structures are available, strengthening by applying

GFRP laminate has become popular. For strengthening purposes, application of GFRP

laminate is more advantageous than other materials. Teng et al. (2002) pointed out that, there

is increased demand for extensive research work to improve the characteristic behavior of

FRP materials to establish their application acceptability in RC structures, beams, slabs and

columns. In particular, their practical implementations for strengthening civil structures are

numerous. Several researchers pointed out that most of the pragmatic works consist mainly of

the rectangular beams. Furthermore, the design methodologies as well as guidelines are

evolved mainly for the simply supported rectangular beams. Generally, the research works

were conducted on RC rectangular sections which are not truly representative for the fact that

most RC beams would have a T Section due to the presence of a top slab.

Although many research studies had been conducted on the strengthening and repairing of

simply supported RC beams using external plates, there is little reported work on the behavior

of strengthened RC-T beams. Especially, works relating to the application of GFRP laminate

for strengthening the tension zone of RC T- beams in the presence of column are very few.

The negative moment region or the support region of continuous reinforced concrete (RC)

beams is a critical one due to the simultaneous occurrence of maximum moment and shear. In

addition, there are few difficulties arise due to the presence of columns and other components

such as electric and plumbing lines or HVAC ducts.

These columns and components hinder the process of applying CFRP laminate in this

region using conventional techniques. Another important point is that, the use of thick steel

plates for strengthening will raise the floor level, which might be undesirable. An exhaustive

literature review has revealed that, a little amount of research works had been done to address

the possibility of strengthening the tension zone of RC T- beam in presence of column using

FRP materials. In this context, due its low profile and ease of installation, composite materials

such as carbon fiber reinforced polymer (CFRP) can be used to provide an economical and

versatile solution for extending the service life of structures. CFRP laminates may provide

strengthening solutions for all types of structural elements such as beams, columns, walls and

slabs (Nanni, 1999).

2. EXPERIMENTAL PROGRAM

Experimental investigations were carried out on the test specimens to study the properties of

concrete. The specimens such as cubes, cylinders and prism were used to study the following

properties. The specimens cast and tests carried out are given in Table 1.

(a) Compressive Strength

(b) Split Tensile Strength

(c) Flexural Strength

Experimental Study of Reinforced Concrete Continuous Rectangular and Flanged Beams at

Support Region


Table 1 Types of tests and Specimen Sizes

S.NO Properties studied Specimen No.of specimens Specimen size (mm)

1 Compressive strength Cube 06 150 x 150 x 150

2 Split tensile strength Cylinder 03 150 x 300

3 Flexural Strength Prism 04 150 x 150 x 700

2.1. Compressive Strength

The compressive strength of concrete is determined at the age of 7 days and 28 days using

cubes. The test was carried out on 150mm x 150mm x 150mm size cube as per IS: 516-1959.

A 2000kN capacity standard compression testing machine was used to conduct the test and

the test results are shown in Table 2.

Table 2 Compressive Strength Test Results

Specimen Compressive Strength

(N/mm2)

Average Compressive

Strength (N/mm2)

At 28 Days

Specimen 1 26.60

27.35 Specimen 2 28.12

Specimen 3 27.33

2.2. Split Tensile Strength

The split tensile strength of concrete is determined at the age of 28 days. The tests were

carried out on 150x300 mm size cylinder. The load was applied till the failure of the cylinder

specimens and the results are shown in Table 3.

(1)

Table 3 Split Tensile Strength Test Results

Specimen Split Tensile Strength

(N/mm2)

Average Split Tensile Strength

(N/mm2)

At 28 Days

Specimen 1 5.79

5.75 Specimen 2 5.82

Specimen 3 5.63

2.3. Flexural Strength

Flexural strength is one of the measure of tensile strength of concrete. It is a measure of an

unreinforced beam or slab to resist failure in bending. It is measured by concrete beams with

span length at least three times the depth. The flexural strength is expressed as Modulus of

rupture in mPa and is determined by standard test methods ASTMC 78(third -point loading)

or ASTMC (centre point loading). Flexural strength of concrete is about 10 to 20 percent of

compressive strength depending on the type, size and volume of coarse aggregate used.

Flexural strength of various specimens casted are provided in Table 4.



Table 4 Flexural Strength Test Results

Specimen Flexural Strength (N/mm2)

Average Flexural Strength

(N/mm2)

At 28 Days

Specimen 1 7.45

7.3 Specimen 2 7.12

Specimen 3 7.33

2.4. Experimental Setup of RC T- Beams

A total of two RC T-beams and One Rectangular beam were fabricated for this experimental

program. Reinforced concrete T beam specimen of size as shown in the fig (Length = 2.6m ,

flange width = 500mm , web width = 100mm, depth of the flange = 75mm) and all having the

same reinforcement detailing are cast. Reinforced concrete Rectangular beam of size

2.6x0.1x0.175m is cast. For all the two reinforced concrete T beams, the same arrangement

for flexure and shear reinforcement is made. The tension reinforcement consists of 2 nos of 10

mm diameter and 2 nos of 8 mm diameter HYSD bar and 6mm diameter rings are placed

@150mm c/c. In flange 8mm diameter main rods and four bars of 6 mm diameter HYSD bars

are provided as distributors. The Rectangular beam is reinforced with 2 nos of 10 mm

diameter and 2 nos of 8 mm diameter HYSD bar and 6mm diameter rings are placed

@150mm c/c. The detailing of reinforcement of the beam is shown in Fig.1. All the beams

were casted with M25 grade concrete and tested after 28 days. Fig 2 shows the beam with

mould and reinforcement detailing as specified . One of the T beam and Rectangular beam

was tested without FRP reinforcement, and was identified as Beam B0 and B1. The other T

beam is identified as Beam B2, was strengthened in both flexure and shear.

Figure 1 Reinforcement Detailing of T- Beam

Figure 2 .Beams with their moulds

Experimental Study of Reinforced Concrete Contin

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For flexural strengthening of Beam B2, two plies of 0.8mm thick GFRP laminates were

applied on the flanges. The strengthening system was applied to the surface of

standard procedure specified by the manufacturer. The surface treatment of concrete prior t

the installation of strengthening system was done using water jetting,

which proved to be very effective and environmentally friendly.

beam is shown in fig 4.

Figure 4

The beams were tested as simply supported T

purpose of the test setup was to obtain tension on the flanges, as in the case of the negative

moment region of a continuous beam. The supports represented the points of inflection of a

continuous beam, where the bending moment is zero. Linear Variable Differential

Transformers (LVDTs) were placed at mid span and quarter span to monitor the deflection of

the beam and at the supports to measure settlement. T

fig 5.

Figure 5

3. RESULTS AND DISCUSSI

Beam B0 failed in the classical flexural failure mode, which is characterized by yielding of

the tension steel followed by the crushing of concrete in the compression zone. Beam B1

failed in the flexural failure mode, which is characterized by yielding of

followed by the crushing of concrete in the compression zone. The strengthened beams also


Support Region

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strengthening of Beam B2, two plies of 0.8mm thick GFRP laminates were

The strengthening system was applied to the surface of

standard procedure specified by the manufacturer. The surface treatment of concrete prior t

the installation of strengthening system was done using water jetting,

which proved to be very effective and environmentally friendly. Fixing of GFRP sheet on

Figure 4 Fixing of GFRP sheets on the beam

ed as simply supported T-beams under two point bending. The



beam, where the bending moment is zero. Linear Variable Differential


the beam and at the supports to measure settlement. The test setup is shown in the following

Figure 5 Test setup of rectangular beam and T-Beam

RESULTS AND DISCUSSION



failed in the flexural failure mode, which is characterized by yielding of


uous Rectangular and Flanged Beams at

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strengthening of Beam B2, two plies of 0.8mm thick GFRP laminates were

The strengthening system was applied to the surface of the beam using

standard procedure specified by the manufacturer. The surface treatment of concrete prior to

Fixing of GFRP sheet on

beams under two point bending. The



beam, where the bending moment is zero. Linear Variable Differential


he test setup is shown in the following



failed in the flexural failure mode, which is characterized by yielding of the tension steel




exhibited flexural failures. All beams cracked at practically the same level of load, at about 40

kN. The Failure modes of beams B0, B1, B2 are shown in fig 6,7 & 8 respectively. After

cracking, the decrease in stiffness in Beam B0 was larger than in Beams B1 and B2. The

ultimate strength of Beams B1 and B2 were higher than that of the Rectangular beam,

respectively.

Figure 6 Final failure in beams by crushing of concrete (beam B0)

Figure 7 Failure modes of rectangular beam at support and mid span (beam B1)

Figure 8 Final failure in beams by crushing of concrete (beam B2)


Support Region


3.1. Load Deflection Analysis

Here the deflection of each beam at different positions is analyzed. Mid-span deflections of

each beam are compared with the control beam. It is noted that the behavior of the flexure

deficient beams when bonded with GFRP sheets are better than the control beams. The mid-

span deflections are lower when bonded externally with GFRP sheets. The use of GFRP sheet

had effect in delaying the growth of crack formation.

Beam B0 is the Rectangular Beam. In Beam B0 no strengthening is done. Two point static

loading is applied on the beam and at the each increment of the load, deflection at L/3, L/2

and 2L/3 are taken with the help of dial gauges. Using this load and deflection data, load vs.

deflection curve is plotted and is shown in fig 9. At the load of 25kN initial hairline cracks

appeared. Later with the increase in loading values the crack propagated further. The Beam

B0 failed completely in flexure.

Beam B1 is the T-beam. In Beam B1 no strengthening is done. Two point static loading is

applied on the beam and at the each increment of the load, deflection at L/3, L/2 and 2L/3 are

taken with the help of dial gauges. Using this load and deflection data, load vs. deflection

curve is plotted and is shown in fig 9. At the load of 40kN initial hairline cracks appeared.

Later with the increase in loading values the crack propagated further. The Beam1 failed

completely in flexure.

Beam B2 is strengthened only at the flange at one third distance .Two point static loading

is applied on the beam and at the each increment of the load, deflection at L/3, L/2 and 2L/3

are taken with the help of dial gauges. Using this load and deflection data, load vs. deflection

curve is plotted and is shown in fig 9. At the load of 55kN initial hairline cracks appeared.

Later with the increase in loading values the crack propagated further. Beam B2 failed due to

fracture of GFRP sheet and then flexural failure of the beam took place.

Figure 9 Load Deflection Diagram

4. CONCLUSIONS

The present experimental study is done on the behavior of reinforced concrete continuous T-

beams in negative moment region strengthened by GFRP sheets. From the test results and

calculated strength values, the following conclusions are drawn:

• The ultimate load carrying capacity of T-beam is 23% more than that of the Rectangular

beam.

• Initial flexural cracks appears at 40kN in the control beam and at 55 kN in case of

strengthened beams.



• The Uultimate load carrying capacity of rectangular section is 130 kN, flanged section is 160

kN and FRP Flanged section is 175 kN.

• The load carrying capacity of the strengthened Beam was found to be maximum of all the

beams. It increased up to 37.5 % more than the control beam

• The deflection of the strengthened flanged beam reduced by 5% in all the load cases.

• Externally bonded GFRP laminates are very effective in enhancing the strength, in both

flexural and shear, and stiffness of the negative moment region of T-beams.

REFERENCES

[1] ACI Committee 440 (1996) State Of Art Report On Fiber Reinforced Plastic

Reinforcement For Concrete Structure ,ACI 440R-96, American Concrete Institute ,

Farmington Hills, Michigan

[2] Nanni, A ., Khalifa A ., Improving shear capacity of existing RC T-section beams using

CFRP composites Cement & Concrete Composites 22(3) ,2000,pp. 165-174.

[3] Muhammad Mukhlesur Rahman and Md. Waliur Rahman ,Simplified method of

strengthening RC continuous T beam in the hogging zone using carbon fiber reinforced

polymer laminate – A numerical investigation journal of Civil Engineering and Concrete

Technology 4(6), 2013,pp. 174-183

[4] Sinaph M. Namboorimadathil, J. Gustavo Tumialan, Antonio Nanni, Behavior of rc T-

beams strengthened in the negative moment region with CFRP laminates, San Francisco,

CA ICCI June 2002.

[5] Christos G. Papakonstantinou, Konstantinos Katakalos, George C. Manos, reinforced

concrete t-beams strengthened in shear with steel fiber reinforced polymers 6th CICE,

Rome (2012).

[6] Abdul Ridah Saleh ,Ammar Abd Alameer Hussein Barem(2013), Experimental and

Theoretical Analysis for Behavior of R.C. Continuous Beams Strengthened by CFRP

Laminates Journal of Babylon University/Engineering Sciences 21(5), pp.1555-1567.

[7] Y. Haryanto, I. Satyarno , D. Sulistyo ,Strength and ductility of reinforced concrete t-

beams strengthened in the negative moment region with wire rope and mortar composite ,

Journal of the Civil Engineering Forum 21(1),2012.

[8] M. Z. Jumaat, M. M. Rahman* and M. A. Alam, Flexural strengthening of RC continuous

T beam using CFRP laminate, International Journal of Physical Sciences, 5(6), 2010, pp.

619-625.

[9] Ross, C. A., Jerome, D. M., Tedesco, J. W., and Hughes, M. L. , Strengthening of

reinforced concrete beams with externally bonded composite laminates, ACI Structural

Journal, 96(2), pp. 65-71.

[10] M.S.Shetty , Concrete Technology : theory and practice , S. Chand, 2008, pp.624.

[11] Lalramnghaki Hauhnar, R. Rajkumar and N. Umamaheswari, Behavior of Reinforced

Concrete Beams with Circular Opening in the Flexural Zone Strengthened by Steel Pipes.

International Journal of Civil Engineering and Technology, 8(5), 2017, pp. 303-309

[12] M. Rajesh Reddy, Dr. N. Srujana and N. Lingeshwaran, Effect of Base Isolation in

Multistoried Reinforced Concrete Building. International Journal of Civil Engineering

and Technology, 8(3), 2017, pp. 878–887

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EXPERIMENTAL STUDY O F REINFORCED …...A total of two RC T-beams and One Rectangular beam were fabricated for this experimental program. Reinforced concrete T beam specimen of …