An efficient compound-element for potential progressive collapse analysis of steel frames with semi-rigid connections

In this paper, the formulation of a novel 1D frame compound-element for the materially and geometrically non-linear analysis of steel frames with flexible connections is outlined. The element is formulated based on the force interpolation concept and the total secant stiffness approach, and implemented in a FORTRAN computer code. The accuracy and efficiency of the formulation are verified through some numerical examples. For steel frames with bolted flush end-plate and extended end-plate connections, a static and dynamic progressive collapse assessment based on the alternate load path (ALP) method is undertaken by employing the developed analytical tool and dynamic load factor (DLF) is estimated. Furthermore, the implications of analyzing semi-rigid steel frames based on the assumption of fixed connections and the effects of the connection details on the global response of a frame during different progressive collapse scenarios are investigated.