Progressive collapse analysis of steel moment frames considering joint behaviour

In this study, the progressive collapse potential of steel moment frames is investigated using alternate load path method (APM) recommended in the General Services Administration (GSA 2003) and Department of Defense (DoD-UFC 4-023- 03, 2009) guidelines. The developed finite element model includes the geometric and material nonlinearities and considers the influence of joint behaviour under extreme events. Co-rotational formulation is used to model geometrical nonlinearity. The implicit Newmark method is adopted to handle the dynamic capability. The component-based joint method, which allows one to obtain the strength and stiffness characteristics of all different components of a joint including the column web panel zone, is used to model the joint behaviour. The analysis results show that the location of column removal has significant influence on the progressive collapse potential of frames. The number of building storeys also has some effects. This paper shows that the alternate load path method is a useful approach for assessing the ability of a structural system to absorb the loss of a critical column member. It also highlights the urgent need for a robust and reliable numerical tool to perform this kind of assessment.