Experimental and numerical study on collapse modes of single span steel portal frames under fire

Abstract

This paper presents experimental and numerical investigations on the collapse modes of single span steel portal frames exposed to fire. A fire test on a scaled-down single span steel portal frame is conducted and measurements of deformation and collapse mode of the test frame are used to validate the numerical model for simulating the behavior of the single span steel portal frames subjected to fire. Four collapse modes of the portal frames, column lateral collapse, column buckling collapse, overall inward collapse and overall outward collapse, are revealed through parametric studies with the validated numerical model. The effects of heating conditions, stiffness of column base, temperature gradient, fire protection, load ratio, span-height ratio and column spacing on collapse modes of single span steel portal frames in fire are obtained. It is found that heating conditions, stiffness of column base and load ratio have a great impact on the portal frame collapse modes while temperature gradient and fire protection mainly affect the column collapse modes. The findings of this study lay the foundation for early-warning of fire-induced collapse of single span steel portal frames.