Numerical investigation on moment redistribution of continuous reinforced concrete beams under local fire conditions

This article presents a numerical investigation on the mechanical behaviours, such as the fire resistance, the moment redistribution and the failure mode, of continuous reinforced concrete beams with two spans and three spans under the standard fire of ISO-834. Firstly, a 3D finite element model was established and validated against the fire test beam. Secondly, the three stages associated with the fire time of fire behaviour for the continuous reinforced concrete beams were divided and explained. An index of the moment redistribution amplitude was modified and used to evaluate the fire performance of continuous reinforced concrete beams. A series of parametric analyses for continuous reinforced concrete beams with two spans were conducted in order to investigate the influence of some parameters such as the load ratio, the load position, the support condition and the sectional size. Finally, the distributions of the vertical deflection and the plastic hinge within beam spans and the failure modes for continuous reinforced concrete beams with three spans under local fire conditions were discussed emphatically.