Comparative fire behavior of composite girders under flexural and shear loading

This paper presents results from an experimental study on the fire behavior of composite steel girders subjected to high shear loading. Four steel-concrete composite girders, comprising of steel girders and concrete slab, were tested under simultaneous structural loading and fire exposure. The first composite girder was subjected to typical flexural loading and fire conditions, while the other three girders were subjected to high shear loading and exposed to fire conditions. The main test variables are level of composite action, type and magnitude of loading. All tested girders failed in less than one hour of fire exposure, however, their failure mode varied significantly. For instance, composite girder subjected to flexural loading failed through flexural yielding of steel girder with large rotation at end supports, while girders subjected to high shear loading failed with no signs of large deflections or rotations at end supports.