Investigating the Seismic Design Lateral Force Distribution of a Tall Steel Moment Frame Building Based on Inelastic Behaviour

In recent earthquakes, most of the observed collapses have been related to inappropriate distributions of strength and stiffness of structural elements. Since most building structures designed according to currentcode procedures are expected to undergo large deformations in the inelastic range when subjected to major earthquakes, lateral force distributions can be quite different from those given by the code formulas. One of the essential elements of performance-based seismic design of structures should be touse more realistic design lateral force distribution, which represents peak lateral force distribution in astructure in the inelastic state and includes the higher mode effects. In this paper, design lateral force distribution of the 20-story steel moment resistant frames located in Los Angeles, which was the subject of an extensive analytical study as part of the SAC project, has been investigated using dynamic timehistory analyses results. The maximum story shear at each level, under twenty ground motion records at 10% and twenty at 2% probability of exceedance in 50 years, obtained from nonlinear time history dynamic analyses, and compared with the code lateral load pattern. OpenSees software has been used in this paper for modeling and performing analyses. It is concluded that code lateral force distribution does not able to accurately predict deformation and force demands that may be induced during nonlinear phase; causing structures to behave in a rather unpredictable and undesirable manner

کلیدواژه ها:

Tall ، Steel frame ، Inelastic behavior ، Lateral distribution