Dynamic increase factor for progressive collapse analysis of semi-rigid steel frames

Yan Fei Zhu, Chang Hong Chen*, Yao Yao, Leon M. Keer, Ying Huang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


An empirical and efficient method is presented for calculating the dynamic increase factor to amplify the applied loads on the affected bays of a steel frame structure with semi-rigid connections. The nonlinear static alternate path analysis is used to evaluate the dynamic responses. First, the polynomial models of the extended end plate and the top and seat connection are modified, and the proposed polynomial model of the flush end plate connection shows good agreement as compared with experimental results. Next, a beam model with nonlinear spring elements and plastic hinges is utilized to incorporate the combined effect of connection flexibility and material nonlinearity. A new step-by-step analysis procedure is established to obtain quickly the dynamic increase factor based on a combination of the pushdown analysis and nonlinear dynamic analysis. Finally, the modified dynamic increase factor equation, defined as a function of the maximum ratio value of energy demand to energy capacity of an affected beam, is derived by curve fitting data points generated by the different analysis cases with different column removal scenarios and five types of semi-rigid connections.

Original languageEnglish (US)
Pages (from-to)209-221
Number of pages13
JournalSteel and Composite Structures
Issue number2
StatePublished - Jul 25 2018


  • Alternate path method
  • Dynamic increase factor
  • Nonlinear static analysis
  • Progressive collapse
  • Semi-rigid steel frame

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Metals and Alloys


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