Dynamic Increase Factor for Progressive Collapse Analysis of Steel Structures

Progressive collapse refers to a phenomenon in which a local damage of a primary structural element leads to the failure of partial or whole structural system. To investigate the progressive collapse of structures, three analysis procedures: linear static, nonlinear static and nonlinear dynamic procedures can be used. For static analysis, the gravity force applied on the column removed bay should multiply by a constant factor 2. Using a constant Dynamic Increase Factor (DIF) is appropriate only for elastic systems. According to optimal design of structures, assuming elastic behavior after column removal scenario is conservative. Thus, it is necessary to establish expression for DIF that consider inelastic response. In this paper, using load-displacement and capacity curve of a clamped-clamped steel beam, an explicit expression for DIF is established for elastic-perfectly plastic and elastic-plastic with catenary action behavior.