Seismic response estimation of mid-rise steel moment frame buildings using a new energy-based methodology

Abstract

Nonlinear Time History Analysis (NTHA) contains a complex and rigorous process for structural seismic evaluation. Nonlinear static (Pushover) analysis can simplify this process. This paper aims to develop an energy-based seismic assessment methodology using pushover analysis. This methodology can estimate the response of mid-rise buildings with much fewer computational operations than NTHA and consider higher mode effects. Other advantages of the proposed procedure include using the capacity curve of Multiple Degrees Of Freedom (MDOF) systems directly instead of the Equivalent Single Degree Of Freedom (ESDOF) and computing the energy demand of the structure based on the mean spectrum corresponding to the desired hazard level instead of the various earthquake record spectrums. The proposed methodology converts the pushover capacity curve to the energy capacity curve for each mode, and the energy demand curve is superimposed on it. The intersection of these two curves is considered the target response. NTHA and Modal Pushover Analysis (MPA) are employed to validate and compare the proposed methodology with other ones. Also, 4, 8, and 9-story steel moment frame buildings are selected, modeled, and analyzed using OpenSEES software. The results show that the proposed methodology can estimate the responses of the building with reasonable accuracy compared to the mean results of the NTHA. Also, the proposed method significantly reduces the error of the responses compared to the MPA. Nevertheless, it can be concluded that the proposed energy-based methodology can be a simple, efficient, and rapid alternative for NTHA.

Keywords

• seismic evaluation
• pushover analysis
• energy-based methodology
• higher mode effects
• steel frames