Fragility analysis of steel moment-resisting frames subjected to impact actions

In recent decades, researchers have been examining the behavior of structures subjected to abnormal loadings such as fire, blast, and vehicle collision. Extreme actions like the impact force of light and heavy vehicles on the external column of steel buildings, whether accidentally or purposely, are an essential research topic among the many impact loading scenarios. Since the impact loads induced by vehicle collisions on external building columns are rarely considered in the design procedure, so, the effect of these loads on the nonlinear performance of structures needs to be investigated thoroughly by using nonlinear dynamic time history analyses and fragility curves. In this study, 2D steel moment-resisting frames (SMRFs) with 2, 5, 8, and 12-story with an intermediate ductility are designed for gravity and seismic loads. Then, nonlinear dynamic time history analyses are performed using OpenSees software under the impact loads induced by light and heavy vehicles collisions with corner column of mentioned frames. Next, Fragility curves are proposed based on the various damage levels for interpretation of probabilities. The results of the probabilistic analyses showed that among the studied frames, mid-rise 8-story frame had more collapse capacity and low-rise 2-story frame had less collapse capacity against vehicle impact. For example, the average collapse velocity for low, medium, and severe damage levels of a 2-story frame is equivalent to 27, 37 and 69 km/h under the impact of a light vehicle collision, respectively. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.