Kumpei Azai, Jiro TAKAGI
The collapse behavior of steel floor structures in fire was investigated using detailed three-dimensional finite element models. A typical steel office building with long-span beams and uninsulated secondary beams was analyzed, considering variations in fire compartment location, primary beam temperature, and slab reinforcement. Large deformation behavior under elevated temperatures was numerically evaluated. It was found that the dominant load-carrying mechanism and collapse mode significantly depend on these factors. The vertical load carrying paths can be relocated associated with catenary and membrane actions. It was suggested that performance-based fire design may allow uninsulated primary beams under certain conditions.