Analysis of Steel Structures in Fire with Force-Based Frame Elements Available to Purchase

This paper considers the extension of the force-based element formulation to simulate the nonlinear, temperature-dependent response of structural frames exposed to fire. The two-dimensional formulation presented here accounts for thermal expansion, temperature-dependent material properties, and residual stresses. The element utilizes a fiber discretization to simulate the gradual plastification of the section. Geometric nonlinearities are included through coordinate transformations of the corotational reference frame. Analyses of benchmark experimental tests demonstrate that the force-based element formulation is computationally stable and provides accurate results for structures exposed to fire. In addition, comparisons to traditional displacement-based elements indicate that the force-based element may offer improved computational efficiency because fewer elements are needed per member.