Techno Press


Steel and Composite Structures   Volume 22, Number 3, October30 2016, pages 677-690
DOI: http://dx.doi.org/10.12989/scs.2016.22.3.677
 
Effects of damping ratio on dynamic increase factor in progressive collapse
Javad Mashhadi and Hamed Saffari

 
Abstract     [Full Text]
    In this paper, the effect of damping ratio on nonlinear dynamic analysis response and dynamic increase factor (DIF) in nonlinear static analysis of structures against column removal are investigated and a modified empirical DIF is presented. To this end, series of low and mid-rise moment frame structures with different span lengths and number of storeys are designed and the effect of damping ratio in DIF is investigated, performing several nonlinear static and dynamic analyses. For each damping ratio, a nonlinear dynamic analysis and a step by step nonlinear static analysis are carried out and the modified empirical DIF formulas are derived. The results of the analysis reveal that DIF is decreased with increasing damping ratio. Finally, an empirical formula is recommended that relates to damping ratio. Therefore, the new modified DIF can be used with nonlinear static analysis instead of nonlinear dynamic analysis to assess the progressive collapse potential of moment frame buildings with different damping ratios.
 
Key Words
    progressive collapse; alternate load path; nonlinear static analysis; dynamic increase factor; damping ratio
 
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