Strength reduction factor demands for building structures under different seismic levels

Damage levels of building structures under a design earthquake are closely related to the assigned values of strength reduction factors. This paper is to investigate the strength reduction factor demands of building structures that were designed considering various earthquake ground intensity levels, soil ground types, and strength reduction factors. In the investigation, a huge number of rigorous nonlinear inelastic dynamic response analyses of various analytical models of five-story and nine-story frame structures were conducted under various generated ground motions with variations in phrase angles but identical response spectral acceleration amplitudes. Various scaled earthquake records were also considered for evidence of the investigation. The obtained results showed that when the same values of the strength reduction factors were used for determination of the design lateral seismic forces, the damage and reliability level demands of the structures designed for moderate seismic areas were much less than those for severe seismic ones. As a result, it is proposed that the strength reduction factor demands given in design codes can additionally be expressed in a linear relation of the maximum ground acceleration. Copyright (c) 2012 John Wiley & Sons, Ltd.