Finite element modelling and parametric analysis of FRP strengthened RC beams under impact load

In this study, a non-linear three-dimensional finite element model was developed to study the impact behaviour of reinforced concrete beams strengthened in shear and/or flexure with carbon-FRP (CFRP) sheets. Concrete damage plasticity model was used for the concrete part, a traction-separation law for the CFRP-concrete interface, and Hashin criteria for rupture in CFRP. Comparisons with experimental data from literature, for various properties, confirmed the accuracy of developed model. A detailed parametric analysis was performed focusing on: the impact location as a ratio (a) from support to mid-span, impact velocity (v); and several geometrical properties related to CFRP technique. Increasing a from 0.26 to 0.79 results in increasing the maximum displacement (Amax) for both un-strengthened and strengthened beams. CFRP strengthening resulted in decreasing Amax for different values of a and v and prevented global concrete failure for v = 8.86 m/s. Delta(max) is also decreased by 13% when a round corner and an arched soffit were used to prepare the beam substrate for bonding the transverse sheets instead of a sharp corner. Furthermore, the paper presents detailed discussions and implications for the above parameters and two additional ones, namely: configuration of transverse sheets (continuous wraps or discontinuous strips) and thickness of CFRP longitudinal sheets.