Modelling of steel structures for progressive collapse mitigation: The contribution of lateral force resisting systems

Abstract

Progressive collapse research in the past decade focused on understanding the nonlinear dynamics behaviour of the structural system after a primary structural member loses capacity to carry its load. The author is of the opinion that progressive collapse resistant design should take advantage of native structural systems that are part of the original design rather than create new systems or adopt unduly complicated approaches. Certain types of lateral force resisting systems such as Outrigger-belt system could contribute to mitigation of progressive collapse by transferring load from damaged/removed members to other parts of the structure through an alternate load path. This paper demonstrates the capability of outrigger-belt lateral force resisting system for transferring gravity load from damaged members to other parts of the structure. Steel structures are particularly vulnerable to instability related failures due to their inherent slenderness; therefore, any analysis must explicitly consider geometric nonlinearity. The results reported here were obtained using the nonlinear static analysis and AISC Direct Analysis Method which accounts for geometric nonlinearity. © Civil-Comp Press, 2011.

Keywords: Direct Analysis, Outrigger-Belt System, Progressive Collapse, Second Order Effects, Steel Structures