Blast Testing of Steel Frame Assemblies to Assess the Implications of Connection Behavior on Progressive Collapse

Abstract

Terrorist bombings of buildings in the United States of America over the past decade have created an urgent need for all governmental and code agencies to provide guidance for the analysis and design of structures to reduce the potential for progressive collapse under abnormal loading conditions. This paper presents the results to date of a first-ever, multi-year steel frame blast research program sponsored by the General Services Administration (GSA) of the Office of Chief Architect (OCA), as part of an historic integrated inter-agency test program with the Defense Threat Reduction Agency (DTRA) as an integral part of DTRA's Blast Effects Tests Series. GSA's primary program goals and objectives are threefold, viz. 1) to evaluate the behavior of steel frame connections subjected to large scale arena explosive tests, 2) to determine their post-blast integrity for the purpose of mitigating progressive collapse, and 3) to identify and prescribe effective solutions. This paper examines the blast resistance and overall structural performance of selected steel frame beam-to-column moment connection configurations when subjected to direct air blast attack, including the effects of high strain rates in critical components and welds, and evaluates the post-blast integrity of those same moment connection configurations needed to arrest structural mechanisms that are known to trigger progressive collapse. Gaining this knowledge is of strategic importance to the GSA in light of the fact that the GSA has found steel framed structures to be characteristically cost-effective to build due to their light weight when compared to concrete structures, and because they are typically erected much faster with a corresponding reduction in construction time.