Improving seismic performance of steel IMRFs using quarter-elliptic bracings

In the present study, seismic performance of steel moment resisting system equipped with quarter-elliptic braces has been evaluated by conducting linear and nonlinear analysis in different software. The main aim of this study is to evaluate seismic behavior of this bracing system through calculating the response modification coefficient, Rμ factor, and comparing the results to intermediate moment resisting systems. In order to calculate the response modification coefficient and overstrength factor, push over and incremental dynamic analysis have been used on two, four, six and eight-story archetypes in accordance with standard methodologies and guidelines. Accordingly, it was concluded that R factor and overstrength factor, Ω۰, can be assumed ۶ and ۲.۵ respectively for this type of earthquake resisting system. In addition, the comparison of the performance of this system with intermediate moment resisting system revealed that, the former is better in terms of energy dissipation and economical design.

Keywords:

quarter-elliptic bracing , innovative steel structures , seismic performance factors assessment , FEMA P۶۹۵