Torsional irregularity in multi-story structures

Günay Özmen,Yavuz Durgun,Konuralp Girgin

doi:10.1007/s40091-014-0070-5

Abstract

The purpose of this study is first to determine the conditions for excessive torsional irregularity and then to discuss the validity of code provisions. A parametric investigation is performed on six groups of typical struc- tures with varying shear wall positions, story, and axis numbers. It is found that torsional irregularity coefficients increase as the story numbers decrease, i.e., maximum irregularity coefficients occur for single-story structures. They reach maximum values when the asymmetrical shear walls are placed as close as possible to the centers of mass. However, the results obtained for floor rotations are quite contradictory. A new provisional definition for torsional irregularity coefficient based on floor rotations is proposed.

Highlights

Earthquake field investigations repeatedly confirm that irregular structures suffer more damage than their regular counterparts
The purpose of this study is first to determine the conditions for excessive torsional irregularity and to discuss the validity of code provisions
It is found that torsional irregularity coefficients increase as the story numbers decrease, i.e., maximum irregularity coefficients occur for single-story structures

Summary

Introduction

Earthquake field investigations repeatedly confirm that irregular structures suffer more damage than their regular counterparts. A large number of studies exist which investigate various aspects of torsional irregularity including geometric asymmetry (Duan and Chandler 1997; Ozmen 2002; Demir et al 2010; stiffness distribution Ozmen 2002, 2004; Tezcan and Alhan 2001), analysis methods such as pushover and non-linear dynamic analyses. Ozmen (2002) investigated geometric and structural aspects of torsional irregularity according to (Turkish Earthquake Code 2007). Ozmen (2004) determined the shear wall positions which cause excessive torsional irregularity according to TEC2007 and discussed the related code provisions. Dogangun and Livaoglu (2006) examined the differences in results from equivalent seismic load method, mode-superposition method, and analysis method in time domain. They presented some recommendations related to the usage of seismic analysis methods.

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Results

Conclusion