S. A. Haj Seiyed Taghia - Assistant Professor, Qazvin Branch, Islamic Azad University, Qazvin, Iran
A. S. Moghadam - Assistant Professor International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran

This paper examines differences in performances of a range of torsionally stiff and flexible single story buildings designed with the provisions of Iranian Standard 2800. Seismic nonlinear dynamic time history behavior of eight building models subjected to seven horizontal bi-directional design spectra compatible ground motions are investigated. These models cover a wide range of very torsionally stiff to very flexible buildings. Response parameters are element ductility demand and building story drift ratio. These criteria are appropriate indices for structural and nonstructural damages, respectively. This investigation shows that the linear static analysis of building code such as Iranian Standard 2800 is not generally adequate for structures with very low torsional stiffness.

Torsion, Torsionally stiff, torsionally flexible, Standard 2800, Non-linear dynamic analysis, Story drift ratio, Performance level