Calibration of force reduction factors of RC buildings

A. M. Mwafy, A. S. Elnashai

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


A comprehensive study is undertaken to assess and calibrate the force reduction factors (R) adopted in modern seismic codes. Refined expressions are employed to calculate the R factors “supply” for 12 buildings of various characteristics represent a wide range of medium-rise RC buildings. The “supply” values are then compared with the “design" and “demand" recommended in the literature. A comprehensive range of response criteria at the member and storey levels, including shear as a failure criterion, alongside a detailed modelling approach and an extensively verified analytical tool axe utilised. A rigorous technique is employed to evaluate R factors, including inelastic pushover and incremental dynamic collapse analyses employing eight natural and artificial records. In the light of the information obtained from more than 1500 inelastic analyses, it is concluded that including shear and vertical motion in assessment and calculations of R factors is necessary. Force reduction factors adopted by the design code (Eurocode 8) are over-conservative and can be safely increased, particularly for regular frame structures designed to lower PGA and higher ductility levels.

Original languageEnglish
Pages (from-to)239-273
Number of pages35
JournalJournal of Earthquake Engineering
Issue number2
Publication statusPublished - 2002
Externally publishedYes


  • Ductility
  • Force reduction factor
  • Overstrength
  • RC buildings
  • Shear assessment
  • Vertical motion

ASJC Scopus subject areas

  • Safety, Risk, Reliability and Quality


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