Progressive Collapse of Three-Dimensional Semi-Rigid Jointed Steel Frames

Abstract

In this paper, a simplified numerical model is developed for studying the progressive collapse of three-dimensional semi-rigid jointed steel frames under static loading conditions using rotational springs. So far in the literature, limited study has been reported on progressive collapse of semi-rigid jointed frames, especially in the case of three-dimensional (3D) frames. Numerical modeling of semi-rigid connections using the SAP2000 software package and generation of different input requirements are discussed in detail. The results of problems given in the literature are compared for validation of the model. A detailed parametric study is carried out that includes different types of semi-rigid connections and different cases of column removal (i.e., single and consecutive) at different stories. The effects of geometric nonlinearity and debris loading are considered, and reduced 2D models are analyzed to highlight the importance of the 3D model. It is found that the progressive collapse resistance of a frame is influenced not only by in-plane-member end connection characteristics but also by out-of-plane-member end connection characteristics. Based on this study, a new retrofitting scheme for improving progressive collapse resistance is recommended. This study will be useful for engineers and researchers in progressive collapse analysis of 3D semi-rigid jointed frames.