Numerical modelling of CFRP shear-strengthened prestressed concrete beams

A three-dimensional nonlinear finite element (FE) model for carbon fibre reinforced polymer (CFRP) shear-strengthened prestressed concrete (PC) beams was developed and validated against experimental results from the published literature. The PC beams had internal steel as well as externally bonded (EB) CFRP shear reinforcement. A total-strain rotating crack model was used for the concrete. In this model, explicit modelling of the concrete shear behaviour after cracking is not required as the crack plane is always a principle plane with no shear stresses acting on it. The steel reinforcement bars and prestressing tendons were modelled as elastic-plastic materials. An elastic-brittle model was used for the EB CFRP reinforcement whereas the behaviour of the CFRP-to-concrete interface was modelled using a bond-slip model. The validated FE model was used to investigate the influence of concrete compressive strength, effective beam depth, and interaction between internal steel and EB CFRP shear reinforcement on the shear behaviour of the modelled beams. The predicted results showed that the shear strength enhancement could be significant and depended on the studied parameters. The predicted shear force gain due to the EB CFRP sheets increased with the increase in concrete compressive strength and effective beam depth but decreased with the increase in the internal steel-to-CFRP axial rigidity ratio.