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Quantification of Seismic Performance Factors and Ductility of Off-Center Bracing System Composed of Buckling-Restrained Brace Elements

Hosseini Asl, Mohammad Javad | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52692 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Mofid, Masoud
  7. Abstract:
  8. This project aims to determine seismic performance coefficients of Off-Center Braced lateral load resisting system (OBS) equipped with Buckling-Restrained Braces (BRBs), along with comparing its seismic performance in extreme seismicity level with those of Special Moment Frame (SMF). For this intent, the structural design of 24 regular-in-height residential OBS-BRB models was first carried out following ASCE7-16. Then, Static (Pushover) and Incremental Dynamic Analysis (IDA) were performed on the models using the methodology of FEMA P-695 to obtain the target coefficients. Furthermore, the coefficients were used for Pushover and IDA analysis of 27 irregular-in-height OBS-BRB models with soft first or middle stories, in order to establish a collapse safety margin and to assess the applicability of the coefficients on more complex cases. OBS-BRBs are highly preferred over other systems because of their particular geometric layout that allows for large openings and gives room for innovative architectural designs. To furtherly evaluate their seismic performance, dynamic response results of 6 high- and low-period OBS-BRBs excited with different ground-motion records in extreme seismicity level, and the total structural steel spent on them were compared to the ones of 6 SMFs. The results indicate that the seismic performance coefficients and the collapse safety margin are greatly affected by the regularity of the buildings. In addition, a significant decrease was observed in the Collapse Margin Ratio (CMR) with the appearance of a soft story in the building. Moreover, OBS-BRB models showed a higher collapse margin, as well as lower drift ratios and story lateral movements in comparison to the SMFs
  9. Keywords:
  10. Fragility Curve ; Off-Center Brace ; Buckling Restrained Braces Frame (BRBF)System ; Spatial Moment Resisting Frame ; Collapse Analysis ; Seismic Performance

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