Modeling high-rise steel framed buildings under fire

This study evaluates some modeling parameters that affect the use of FE models to predict the behavior and capacity of a high-rise steel moment frame under fire. In particular, the study focuses on the perimeter columns and the girders that frame into them perpendicular to the building's exterior. The parameters examined in this paper are: (1) 3-D frame model versus a 2- D plane frame model; and (2) the representation of the slab in the 2-D plane-frame model. Results from a prototype building frame show that the 3-D and 2-D models experience similar structural behavior and reach the element limit states. The 3-D models, however, require significantly more run time and computational effort. The 2-D models can therefore be used to reasonably and efficiently model the fire-exposed performance of a plane frame. Results also indicate that in the 2-D models, the slab should be considered in the thermal analysis of the girder, but it can be neglected in the structural analysis since it has a negligible effect.