Blast and Impact Loading and Response of Structures
Full Session with Abstracts
Current design standards provide methodologies to analyze and design structures against disproportionate collapse, colloquially referred to in instances as progressive collapse. While these standards generally improve the overall robustness of structures, it is not known with a high degree of certainty, how these structures will perform directly against blast loading. There is a need for blast and structural engineers alike to incorporate disproportionate collapse mitigations that adequately address specific Design Basis Threats (DBT), such as blast. This paper tests the collapse prevention methodology outlined in UFC 4-023-03 (2016), against two typical blast scenarios; a Vehicle Borne Improvised Explosive Device (VBIED) detonated within an internal basement and a VBIED detonated externally with minimal stand-off. In addition to sudden key element removal, these two scenarios capture phenomena unique to blast, such as confinement of the blast wave within the internal building space and upward loading of floor structures. Consideration is given to a typical multi-story structural steel building frame where either the tie force or alternate load method has been applied. Computational Fluid Dynamics (CFD) analysis is used to determine the applied blast loading and Finite Element Analysis (FEA) is used to analyze the highly transient structural response under these loads. Expected levels of damage and the limitations of using a standardized approach to collapse prevention are summarized within this paper. The purpose of this paper is to provide blast engineering practitioners an understanding on the limits of applying general collapse prevention provisions in lieu of an assessment where a blast DBT is considered explicitly.