Thermal-Stress Finite Element Analysis of CFRP Strengthened Concrete Beam Exposed to Top Surface Fire Loading

A detailed 3D time domain transient thermal-stress finite element analysis is performed to study the heat transfer mechanism within a CFRP strengthened reinforced concrete beam for fire conditions initiating at the top of the beam. This loading scenario has not been investigated previously either experimentally or analytically. Accordingly, a reinforced concrete T-beam strengthened with CFRP and fire-tested by other investigators is modeled here to compare the fire rating of top and bottom exposure. The finite element results correlated very well with the experimental measured results for the bottom fire exposure. In addition, the investigation of the top fire exposure yielded important findings on the resistance of concrete beams when subjected to such fire conditions. It is concluded that heating the top surface (slab) of reinforced concrete beams seems to be beneficial in minimizing mid-span deflection.