Structural Evaluation of Tall Steel Moment-Resisting Structures in Simulated Horizontally Traveling Postearthquake Fire

Abstract

Postearthquake fire (PEF) can result in a catastrophe even worse than the earthquake itself. Investigating the effect of PEF loads on structures is thus of paramount importance. On the other hand, because of the complexity of fire, the simulation to account for the thermal loads exerted on structures has always been an issue. Although there are two main methods for simulating real fires—standard fires and natural fires—observations have shown that both of these are more correct for small/medium-size structures. For large open-plan structures, alternative methods (such as traveling fires) should be used. Here, an investigation is performed on a tall seven-story steel moment-resisting structure with a plan area of 900 m2. The structure is first pushed to arrive at a target displacement corresponding to the life safety level of performance according to FEMA code. The damaged structure is then subjected to different traveling fire sizes of 16.7, 50, and 100%. To draw a comparison between the results, a uniform fire (the ISO834 curve) is also considered. The results show that the structure fails at 12, 9, 11, and 16 min under the 16.7% fire size, the 50.0% fire size, the 100% fire size, and the ISO834 fire curve, respectively. The results confirm a considerable difference between the results of a uniform fire and those of traveling fires. It is therefore concluded that the structure is shown to be more vulnerable to PEF loads when the traveling fire methodology is used to calculate the fire resistance.