| General Services Administration(GSA)put out a few editions of guidelines to peruse disproportionate partially and fully failures of buildings,that is known as progressive collapse.This study compares two main distinct editions: GSA2003 and GSA2013,and also shows whether or not can a seismic-designed steel frame building bear progressive collapse according to both versions of GSA.Although there are a few editions of another organization named Department of Defense(DOD)to assess reinforced concrete as well as steel structures for progressive collapse,this study does not include regulations and requirements mentioned in DOD guidelines.For this study,two five-story steel frame buildings were numerically analyzed linearly and nonlinearly using a method named the alternate path(AP)analysis,where critical vertical structural components are deleted and remaining members are examined to span across a lost element.The results we got for the linear analysis were important,where beams resisted loads better according to GSA2013,however,the controlling components for the analysis were the connections that were less vulnerable to progressive collapse according to GSA2003.Moreover,columns were also more serious in GSA2013,though better extreme-column locations were captured for the new guidelines.Although models were analyzed and designed for seismic loads,both of them did not withstand a column loss due to connections’ capacities in the new guidelines.However,both models were safe according to GSA2003.For the nonlinear analysis,GSA2013 proved to be more careful with web and flange compactness of steel sections.As a result,more economic results were found for the new guidelines,notwithstanding the difficulties of calculations needed to assess a building for progressive collapse according to GSA2013.Finally,both models bridged over a column loss successfully except for the corner cases according to the new guidelines. |
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