Effect of shear on fire response of steel beams

Fire resistance of flexural members is derived based on flexural limiting criterion with no consideration to shear failure. However, under certain conditions, shear capacity can degrade at a higher rate than moment capacity in steel beams exposed to fire and this can lead to early failure of beams. This paper discusses the effect of shear on fire resistance of steel beams. For studying this phenomenon, a three-dimensional nonlinear finite element model capable of predicting fire response of steel beams is developed using the finite element package ANSYS. This model is capable of predicting fire response of steel beams under different conditions such as loading pattern, web slenderness and fire insulation. The finite element model is applied to evaluate fire response of beams with different geometrical configurations. It is shown that shear capacity can degrade at a higher rate than flexural capacity in certain scenarios and hence, shear limiting state can be a dominant failure mode in such flexural members.