Moment Redistribution in Continuous RC Beams Top Strengthened with Steel and CFRP Plates

Abstract

It is common practice to retrofit continuous reinforced concrete (RC) beams by fiber reinforced polymer (FRP) or steel plates. This can cause a significant amount of moment redistribution (MR) which results in an efficient and economic design when taken into consideration. There is lack in research regarding MR in continuous RC beams when strengthening plates are applied only at the top side at the hogging regions. The main purpose of this paper is to assess MR in continuous RC beams top strengthened with steel and/or carbon fiber reinforced polymer (CFRP) plates. In this respect, a nonlinear finite element model was developed using ABAQUS 6.14 and validated using experimental research program. The model was found capable of stimulating the behavior of such beams and hence assessing the percentage of MR which can be achieved using steel and CFRP strengthening. A parametric study is conducted to investigate the effect of various parameters, different from those investigated in the experimental program, on the MR in continuous RC beams. Parameters related to the concrete compressive strength, reinforcement ratio, beam thickness and thickness of strengthening plates were considered in this study. The results showed that significant amounts of MR can be achieved using either steel or CFRP plates and that MR is enhanced with the change in concrete compressive strength. Moreover, it was found out that the change in steel bars reinforcement ratio or in thickness of the strengthening plates has different effect on the beams strengthened with steel plates than those strengthened with CFRP plates.