Abstract
This study presents the impact of near-field and far-field earthquakes on the seismic design of Intermediate Moment Resisting Frame (IMRF) and Special Moment Resisting Frame (SMRF) structures through FEMA (Federal Emergency Management Agency) P695 methodology to highlight the importance of probabilistic collapse as well as seismic performance factors of these structures. The purpose of this study is to investigate the collapse performance of steel intermediate and special moment resisting frame systems as the most common structural systems in urban areas in order to assess the seismic performance factors used for the design using nonlinear static and dynamic analysis methods. In this regard, as the representatives of low-rise to high-rise buildings, archetypes with 5-, 10- and 15- story of intermediate and special moment resisting frames are designed and then the nonlinear models are developed in OpenSees software. Nonlinear static analyses are performed to assess the overstrength and ductility of these systems. The effects of near-field and far-field ground motions on these frames are investigated through incremental dynamic analysis. These analyses are performed with 22 far-field and 20 near-field ground motion records using FEMA P695 methodology. The results show that near-field earthquakes have serious impacts on the collapse probability of structures. The superiority of special moment resisting frame over intermediate moment resisting frame is quantified in terms of safety margin and median collapse capacity under both near-field and far-field earthquakes. Finally, the results indicate that the response modification factors introduced in seismic design code are acceptable for intermediate moment resisting frame and special moment resisting frame under far-field ground motions. However, in the near-field sites while SMRF system meets the requirements of FEMA P695 methodology, the IMRF system does not satisfy these criteria.
Highlights
Given that natural disasters such as earthquakes cause huge financial or life losses to societies every year, understanding the essence of earthquakes and the effects of various factors on the behavior of structures has made researchers to create different methods in the analysis and design of structures
Under far-field ground motion records it was reported that all the structures experienced collapse when the ground motion intensity reached 3.0 g, while the probability of collapse for low-rise building was nearly 30% and for mid-to-high rise buildings they were around 90%
In a study conducted by Abdollahzadeh, Sadeghi [42] on the seismic performance factors of 5, 10, 15-story Intermediate Moment Resisting Frame (IMRF) using Young’s method, the results indicated that on average the response modification factor around 5.5
Summary
Given that natural disasters such as earthquakes cause huge financial or life losses to societies every year, understanding the essence of earthquakes and the effects of various factors on the behavior of structures has made researchers to create different methods in the analysis and design of structures. The results of these studies have been used in preparation of rules and regulations for constructions that have become more inclusive and comprehensive over the time. Considering the effects of site’s proximity to seismic sources is an important issue in the seismic design of resistant structures and probabilistic evaluation of buildings should be addressed properly especially under near-field ground motions
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