Numerical Analysis of Steel-concrete Composite Beams Strengthened with Pre-stressed CFRP Plates

Applying pre-stressed Carbon Fiber Reinforced Polymers (CFRP) plate to steelconcrete composite beams is considered an active strengthening technique that can create permanent internal stresses in the beam opposite to the internal straining actions due to the service loads. This study presents a numerical analysis of steelconcrete composite beams stiffened with pre-stressed CFRP plates. The pre-stressing effect on CFRP plate is enforced in the finite element (FE) model as an initial stress on the solid element that used to simulate the strengthening plate and the epoxy is considered as a thin layer between CFRP plate and the steel flange. The deterministic and stochastic analysis is performed to obtain the long-term random responses of the strengthened beams as well as plain beams due to the effect of shrinkage. In addition, the effect of CFRP plate rigidity and strengthening schemes are investigated. By using CFRP plates, strengthening can be achieved up to 25% for the system explored. During the post-elastic range, stiffness is improved when adding pre-stressed CFRP plates and deflection of strengthened beams is reduced by 20% in comparison to the reference beam at the ultimate capacity. Also, a slight drop in ductility occurs with the addition of CFRP plates.