Fiber Beam Element Model for the Collapse Simulation of Concrete Structures under Fire

In order to analyze and simulate the collapse of reinforced concrete (RC) elements under fire, a novel numerical model based on the fiber beam model is proposed in this paper. By dividing the cross section of beam element into many small concrete and steel fibers and assigning different materials to each fiber, this model can consider the non-uniform temperature distribution across the section and simulate the behavior of cracking or crushing for concrete and yielding for steel. The explicit tangential stiffness matrix is deduced for proposed fiber beam with Total Lagrangian (TL) description, and the incremental equilibrium equations are also established. Finally, the proposed fiber model is validated by comparing with various experimental results.