Dynamic Increase Factor for Investigation of Progressive Collapse Potential in Tall Tube-Type Buildings

Abstract

In recent decades, vulnerability of tall buildings to unforeseen loads induced by progressive collapse has drawn researchers’ attentions. There is a growing tendency among engineers to design tall buildings using complicated structural systems with adventurous load paths that are inconsistent with the existing guideline recommendations. Progressive collapse is a dynamic and nonlinear phenomenon. This paper describes a recommended methodology for calculating the dynamic increase factor (DIF) to consider the dynamic effects for nonlinear static analysis. Based on this method, the specific load factor corresponding to the progressive collapse potential of building structures is evaluated by a proposed collapse index. In the development of the methodology, selected tube-type structural systems such as framed tube, braced tube, diagrid, and hexagrid systems were investigated. This study was conducted to assess the collapse behavior of typical 48-story building models under sudden loss of corner load-bearing elements from the first story using nonlinear static and dynamic analyses. The study calculated modified DIF for the validated analytical models via proposed methodology. The results of the proposed method discussed here were in good agreement with nonlinear dynamic analysis results.