Structural Engineering and Mechanics

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The questionable effectiveness of code accidental eccentricity

  • Ouazir, Abderrahmane (Department of Civil Engineering, College of Engineering, University of Ha'il) ;
  • Hadjadj, Asma (Department of Interior Designl Engineering, College of Engineering, University of Ha'il) ;
  • Gasmi, Hatem (Department of Civil Engineering, College of Engineering, University of Ha'il) ;
  • Karoui, Hatem (LR14ES03 Laboratoire d'Ingenierie Geotechnique, Ecole Nationale d'Ingenieurs de Tunis, Universite de Tunis El Manar)
  • Received : 2021.02.22
  • Accepted : 2022.04.12
  • Published : 2022.07.10
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Abstract

The need to account for accidental torsion in seismic design is no longer debatable, however, the seismic codes' requirement for accidental eccentricity has recently faced criticism. In order to get as close to real conditions as possible, this study investigated the impact of accidental torsion in symmetric RC multistory buildings caused by one of its many sources, the torsional earthquake component, and compared the results to those obtained by using the accidental eccentricity recommended by the codes (shifting the center of mass). To cover a wide range of frequencies and site conditions, two types of torsion seismic components were used: a recorded torsion accelerogram and five others generated using translation accelerograms. The main parameters that govern seismic responses, such as the number of stories (to account for the influence of all modes of vibration) and the frequency ratio (Ω) variation, were studied in terms of inter-story drift and displacement responses, as well as torsional moment. The results show that the eccentricity ratio of 5% required by most codes for accidental torsion should be reexamined and that it is prudent for computer analysis to use the static moment approach to implement the accidental eccentricity while waiting for new seismic code recommendations on the subject.

Keywords

Acknowledgement

The authors are thankful to the Deanship of Scientific Research at the University of Ha'il, Saudi Arabia for the financial support under the contract (RG-20 026).

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