Structural Retrofitting of Reinforced Concrete Beams using Carbon Fibre Reinforced Polymer

Abstract: This thesis details experimental work and finite element simulations of reinforced concrete beams retrofitted with carbon fibre reinforced polymer (CFRP). The objectives of this study were to investigate the behaviour of retrofitted beams experimentally, develop a finite element model describing the beams, verifying the finite element model against the experimental results and finally investigating the influence of different parameters on the behaviour of the retrofitted beams. The experimental tests were performed to investigate the behaviour of beams designed in such a way that either flexural or shear failure will be expected. The beams were loaded in four-point bending until cracks developed. The beams were then unloaded and retrofitted with CFRP. Finally the beams were loaded until failure. The ABAQUS program was used to develop finite element models for simulation of the behaviour of beams. The concrete was modelled using a plastic damage model and two models, a perfect bond model and a cohesive model, were evaluated for the concrete-CFRP interface. From the analyses the loaddeflection relationships until failure, failure modes and crack patterns were obtained and compared to the experimental results. The FEM results agreed well with the experiments when using the cohesive model regarding failure mode and load capacity while the perfect bond model was not able to represent the debonding failure mode. The results showed that when the length of CFRP increases the load capacity of the beam increases both for shear and flexural retrofitting. FEM results also showed that the width and stiffness of CFRP affect the failure mode of retrofitted beams. The maximum load increases with increased width. Increased CFRP stiffness increases the maximum load only up to a certain value of the stiffness, and thereafter it decreases the maximum load.

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