Nonlinear finite element analyses of steel/FRP-reinforced concrete beams in fire conditions

In this paper, a simple one-dimensional two-node layered composite beam element is developed for accurate modeling of structural behavior of steel/fiber reinforced polymer-reinforced concrete beams under a combined mechanical and thermal loading in fire conditions. By employing the Timoshenko's beam functions to construct the new element, shear-locking problem is avoided naturally and a unified formulation for analyses of both slender and moderately deep beams is established. A nonlinear finite element analysis based on heat transfer theory is performed to determine the temperature distribution across the cross section of the beam. Both geometric and temperature-dependent material nonlinearities are accounted for. The element is computationally effective, and is demonstrated to be efficient and accurate. The element is easily employed to investigate the influences of a series of parameters on the structural behavior of FRP-reinforced concrete beams in fire conditions, which could provide useful references for structural analysis and design.