Dynamic analyses of bolted-angle steel joints against progressive collapse based on component-based model

Some design methods have been proposed to prevent progressive collapse of building structures. Alternate Path (AP) Method is the most effective and popular one among them. Based on component-based joint models, this paper takes AP Method to study the dynamic performance of two-dimensional (2D) bolted-angle steel joints under a sudden column removal scenario. The comparison between the quasi-static and dynamic responses of the component-based models simulated by finite element software and the experimental test results shows that the component-based models are reliable. After that, based on the validated component-based models, parametric study was conducted in order to study the dynamic responses of bolted-angle steel joints subjected to different levels of sudden gravity loads. These 2D steel joints employ two types of beam-column connections, including web cleat connections and top and seat with web angle connections. Dynamic increased factors (DIFs) are obtained by comparing the acquired dynamic responses with the corresponding nonlinear static responses of the bolted-angle steel joints. Finally, DIFs calculated in this study are compared with the regulations of Department of Defense (DoD) in United States and a simplified energy balance method. As a conclusion, it is found that the numerical results in this study are in good agreement with the energy balance method.