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Proposal for Doctor of Philosophy in Engineering Science

By

Md. Moshiur Rahman

Supervisor : Prof Ir. Dr. Mohd Zamin Jumaat,

Department of Civil Engineering

University of Malaya

50603 Kuala Lumpur

Tel:

Fax:

Email: zamin@um.edu.my

Field of Research: Structural (Civil) Engineering.

Topic of Research proposal: Effective method of strengthening reinforced concrete beams for

repeated loads and fatigues.

Research background:

Fatigue is a process of progressive permanent internal structural change in a material to repetitive

stresses. This changes may be damaging and result in progressive growth of cracks and complete

fracture if the stress repetitions are sufficiently large. A typical reinforced concrete bridge may

experience up to seven hundred million stress cycles during the course of its 120-year life span

(Moss 1972). However, in general, for reinforced concrete a required fatigue life of two million

cycles is considered normal for most applications (Dong, 2003). Under such as high cycle traffic

loading, the structural members like bridge may fail after going through many cycles of tensile

stresses. Thus, it is important to be able to assess the fatigue performance of such structures.

The technique of bonding steel plates or Carbon fiber reinforced plastic (CFRP) plates to the

external surfaces of reinforced concrete structures to enhance its strength or serviceability has been

employed worldwide since the late 1960s. Even though there are some test data on the structural

behaviour of strengthened beams under monotonic static loading, it is very difficult to find the

existing test data on the fatigue behaviour of strengthened beams under repeated loadings

(Saadatmanesh and Malek, 1998, Smith and Teng, 2002, Xiong et al., 2007). Experimenal works

were conducted to study the fatigue behaviour of externally strengthened reinforced concrete beam

with CFRP plate (Meier et al 1995,Inuoe et al 1995, Barnes and Mays 1999, Shahawy and

Beitelman 1999, Hefferman and Erki 2004, Aidoo et al 2004, Eknel et al 2005, Brena et al 2005,

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Gussenhoven and Brena 2005, Toutanji et al. (2006), with prestressed CFRP (Meier et al 1995, El-

Hacha et al. 2003), with Glass Fiber Reinforced Polymer Plate (Shijie and Ruixian 1996,

Papakonstantinou et al 2001), and with steel plate (M. ASCE et al 2003). However, most of

researchers used only one material type to strengthen in their individual works and no comparison

was made to observe relative effectiveness. Tests to investigate the effect of plate thickness on

fatigue performance were hardly found. In addition, there are a few number existing codes or

manuals available for strengthening the reinforcement concrete structures like ACI.2R-02, fib Task

Group 9.3.2001, ISIS Canada2001. However, there is little information regarding effective

consideration for fatigue design. Brena et al 2006 investigated that the maximum composite stress

in the CFRP laminates to strengthen reinforcement concrete beam ranged only from 15 to 25% of

the ultimate strength of the laminates. These values are significantly lower than the limit included

in the ACI 440 design guide for externally bonded composite systems (Kim, Y. J., and Heffernan,

P. J. 2008). Therefore, development of effective and more practical design guideline for externally

bonded composite systems considering fatigue is required for long term sustainability.

The aim of this research work is to investigate the effect of plate thickness on fatigue behaviour of

externally strengthened reinforced concrete beam using two different materials and make a

comparison to see relative performance. A detail design guide line for externally bonded composite

systems subjected to fatigue will also be proposed. To achieve this aim, an extensive experimental

work on externally strengthened and unstrengthened beams will be conducted to examine their

fatigue performance. A numerical analysis will also be made to verify the validity of the test

results. Thus, quantifying the fatigue performance of structural elements externally strengthened

with steel and FRP composites may significantly help in making use of these composites in civil

infrastructure systems.

Objectives of research

The objectives of this research are listed below:

i. To study the behaviour of steel plate and CFRP laminate flexurally strengthened r.c. beams

under repeated loads and fatigues.

ii. To find out the effective methods of strengthening r.c. beams under repeated loads and

fatigues

iii. To eliminate premature failures of strengthened beams under repeated loads and fatigues

iv. To simulate the structural behaviour of flexurally strengthened r.c. beams using finite

element modelling.

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Research methodologies

Generally, the methodology of the study can be summarized as below;

i) Design of strengthened RC beams: Test specimens used in the experiments will be fabricated

according to Euro Code. Design guidelines of strengthened beams under repeated loads and

fatigues will be proposed.

ii) Experimental works: The beams will be strengthened using steel plates and CFRP laminates

for static and repeated loading test. Since the repeated load has the effects of crack propagation of

strengthened beams, eliminating crack induce debonding of strengthened beams under repeated

loads and fatigues will be the main concern of this experiment. Beams will be designed to eliminate

premature IC debonding and will be investigated the structural behaviour under static and repeated

loading. Two million cycles will be used for repeated loading test.

iii) Numerical analysis: All un-strengthened and strengthened beams will be modelled using a

finite element package (LUSAS) and analyzed based on nonlinear structural analysis. The results

are obtained to compare with the experimental results.

Equipment required:

Most of the materials, equipments and facilities required for this research work are available in the

Department of Civil Engineering, University of Malaya. These include,

i) Materials (cement, sand, aggregate, fibre, steel etc)

ii) Mixing and casting equipment (mixture machine, mould, curing tank etc)

iii) ELE concrete compression machine

iv) Devices for data recording (Portable data logger, electrical resistance strain gauge,

demec points, digital demec gauge, LVDT, crack measuring microscope etc)

v) Instron Universal Testing Machine and Hydraulic Jack.

vi) Finite element softwares for modelling.

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Research Flow Diagram

Start

Literature Review

Design of RC Beam

Casting of concrete beam

Flexure strengthening Shear strengthening

Testing Testing

Analysis

Numerical Modeling

Discussion

Recommendation and conclusion

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Schedule of work:

Schedule of work Project duration (Year)

2010

2011 2012 2013

(J~S) (O~D) (J-A) (M-A) (S-D) (J-A) (M-A) (S-D) (J-A) (A-J)

Literature work

Identification

Formulation of test

specimens

Preparation of beam

specimen (Case preparation,

casting, strengthening )

Experimental investigations

(test set-up, instrumentation

and testing)

Analysis of test result

Computer modelling and

simulation of specimens

with experimental results.

Report writing

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Expected Result:

i) New findings : a) To understand the behaviour of steel plate and CFRP laminate flexurally

strengthened r.c. beams under repeated loads and fatigues.

b) To recommend the effective methods of strengthening r.c. beams under repeated loads

and fatigues

c) To recommend for elimination premature failures of strengthened beams under repeated

loads and fatigues

ii) Two papers in ISI Journal

iii) List of Journals : 1) International Journal of fatigue

2) Engineering Structure

3) Composite

Brief Bibliography:

ASCE, M. B. H. O., Cho, J. Y. and Park, D. G. (2003), “ Static and Fatigue Behavior of Reinforced

Concrete Beams Strengthened with Steel Plates for Flexure”, Journal of Structural Engineering, vol. 129,

no. 4, pp.527-535.

Aidoo, J., Harries, K. A., and Petrou, M. F. _2004b_. “Fatigue behavior of carbon fiber reinforced polymer

strengthened reinforced concrete bridge girders.” Journal of Composite for Construction, Vol.8, no6, pp

501–509

Barnes, R. A., and Mays, G. C. (1999). “Fatigue performance of concrete beams strengthened with CFRP

plates.” Journal of Composite for Construction, Vol.3, no.2, pp 63–72

Brena, S. F., Benouaich, M. A., Kreger, M. E., and Wood, S. (2005).“Fatigue tests of reinforced concrete

beams strengthened using carbon fiber-reinforced polymer composites.” ACI Structural Journal, Vol.102,

no. 2, pp 305–313

Dong, Y. (2003),“Static and Fatigue Performance of Reinforced Concrete Beams Retrofitted with External

CFRP Composites”, PhD thesis, UMI Dissertation Services.

Ekenel, M., and Myers, J. J. _2009_. “Fatigue performance of CFRP strengthened RC beams under

environmental conditioning and sustained load.” Journal of Composite for Construction, Vol.13, no.2, pp

93–102

El-Hacha, R., Wight, G. R., and Green, M. F. (2001). “Prestressed fibrereinforced polymer laminates for

strengthening structures.” Prog. Struct. Eng. Mater., Vol.3, pp 111–121.

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Inoue, S., et al. (1996) “Deformation characteristic, static and fatigue strength of reinforced concrete beams

strengthened with carbon fiber reinforced plastic plates” Transaction of Japan Concrete Institute 18, 1996,

pp 143-150

Gussenhoven, R., and Brena, S. F. _2005_. “Fatigue behavior of reinforced concrete beams strengthened

with different FRP laminate configurations.” Fiber-reinforced polymer (FRP) reinforcement for concrete

structures (SP-230), ACI, 613–630

Heffernan, P. J., and Erki, M. A. (2004). “Fatigue behavior of reinforced concrete beams strengthened with

carbon fiber reinforced plastic laminates.” Journal of Composite for Construction, Vol.8 no.2, pp 132–140.

Kim, Y. J., and Heffernan, P. J. (2008), “Fatigue behavior externally strengthened concrete beams with

fiber-reinforced polymers: State of the art.” Journal of Composite for Construction, ASCE Vol.12, no 3, pp

246–256.

Meier, U., Deuring, M., Meier, H., and Schwegler, G. (1992). „„Strengthening of structures with CFRP

laminates: Research and applications in Switzerland.‟‟ Advanced composite materials in bridges and

structures, K. W. Neale and P. Labossiere, eds., Canadian Society for Civil Engineering, Montreal.

Moss, D. S. (1982). “Bending fatigue of high-yield reinforcing bars in concrete.” TRRL Supplementary Rep.

No. 748, Transport and Road, Research Laboratory, Crowthome, U.K

Saadatmanesh H. and Malek A. M. (1998),“Design guidelines for flexural strengthening of RC beams with

FRP plates”, Journal of Composites for Construction ASCE, vol. 2, no. 4, pp.158-164.

Senthilnath, P., Belarbi, A. and Myers, J.J. (2001), “Performance of CFRP Strengthened Reinforced

Concrete Beams in the presence of delimunation and Lap Splices under Fatigue Loading”, Proceedings of

the International Conference on composites in construction (CCC-2001), Porto, Portugal, pp. 323-328.

Shahawy, M. and Beitelman, T. E. (1999),“Static and Fatigue Performance of RC Beams Strengthened with

CFRP Laminates”, Journal of Structural Engineering, vol. 125, no. 6, pp. 613-621.

Smith S. T. and Teng J. G. (2002), “FRP-strengthened RC beams. I: review of debonding strength models”,

Engineering Structures, vol. 24 pp. 385–395

Toutanji, H., Zhao, L., Deng, Y., Zhang, Y., and Balaguru, P. (20060.“Cyclic behavior of RC beams

strengthened with carbon fiber sheets bonded by inorganic matrix.” Journal of Material in Civil

Engineering, Vol.18 no. 1, pp28–35

Xiong G. J., Jiang X., Liu J. W. and , Chen L. (2007),” A way for preventing tension delamination of

concrete cover in midspan of FRP strengthened beams”, Construction and Building Materials, vol. 21, pp.

402–408.