Blast and Impact Loading and Response of Structures
Full Session with Abstracts
To ensure the safety of U.S diplomatic personnel overseas, the U.S Department of State (DoS) has developed façade retrofits capable of resisting high blast loads. Historically, these hardened facades have been primarily used in Reinforced Concrete frame structures which are perceived to perform better against high lateral forces generated by these facades. As the DoS builds and renovates existing steel-framed buildings, it is vital to understand the effects of hardened facades on steel structures to avoid potential collapse situations that would pose a threat to the building occupants.
An analytical study evaluated the global lateral response of steel frames representative of typical diplomatic facilities using hardened and conventional facades against high blast loads. The global blast response was evaluated using non-linear dynamic structural analysis. The study showed that conventionally designed steel frame buildings when used in conjunction with blast-resistant facades, could be susceptible to failure due to the high blast reactions transferred to the Lateral-Force-Resisting-System (LFRS). However, when used with conventional facades, the rapid failure of the façade significantly reduces the loads on the LFRS.
A test program was initiated to validate the findings from the study. Two (2) arena blast tests have been planned using a full-scale, conventionally designed three-story steel braced frame representative of a typical diplomatic office building. Test 1, in which a conventional curtain wall was installed on the steel frame structure was conducted and the results validated portions of the analytical approach and also the initial findings that conventional facades do not generate significant lateral loads on the LFRS. Test 2 which is in progress, will use a hardened façade (designed to resist typical Embassy loads) and is expected to increase the effects (forces and deflections) on the members of the LFRS. The presentation will discuss the results of the analytical study and test program as well as providing an overall review of the research program findings.