Response of RC T-beams strengthened for flexure with staggered CFRP plates

The results of an analytical and experimental study on the behavior of reinforced concrete T-beams retrofitted with carbon-fiber-reinforced polymer (CFRP) plates are discussed in this paper. CFRP plates were bonded to the underside of the beams with the main objective of increasing the service life load capacity. A test series comprising a prototype beam and six 5-m-long simply supported beams were tested under repeated cyclic and monotonic load conditions to failure. Particular emphasis was given to the development of the CFRP plates and to the behavior of the service and ultimate load ranges. This paper examines variables that have not previously been considered such as the use of staggered plates and the use of plates on beam with curtailed longitudinal steel reinforcement. The effect of diagonal tension cracking is also considered in this study by adapting a simple version of the modified compression field theory into the discrete element method. An important conclusion in this paper is that staggered CFRP plates can be used in lieu of full-length plates when considering flexural strengthening of beams.