Analysis of Steel-Concrete Composite Buildings for Blast Induced Progressive Collapse

This paper investigates the progressive collapse behaviour of steel concrete composite buildings subject to ground blast explosion using nonlinear dynamic analysis and conventional alternate path approach. The alternate path approach, which is a threat independent methodology, is commonly used as a design guide for minimising the potential for progressive collapse. This method may not be always conservative in assessing the robustness of the structure, especially for building subject to heavy blast loads and thus nonlinear analysis is often needed to investigate the building response under such extreme load. In the present paper, composite slab model based on equivalent area approach and composite joint model based on Eurocode's component method are proposed for nonlinear analysis of building framework. The analysis results show that a heavy blast load may wipe out a series of columns/beams at once instead of a single one. High blast pressure may also induce large lateral drift and lead to significant damage to structural elements spreading over several storeys of the building. Generally, such extensive damage cannot be captured using the alternate path approach. The present investigation recommends that nonlinear analysis should be performed in order to capture the true behaviour of such buildings subject to extreme blast loads.