Seismic Assessment of Collapse probability In Special Moment Reinforced Frames

In seismically active regions, designing and constructing structures that can withstand severe ground motions with minimal displacement and damage is essential. One of the effective approaches to reducing earthquake-induced damage is performing a seismic fragility assessment of structures. This assessment is thoroughly examined in this research using advanced numerical analyses.The main objective of this study is to assess the seismic fragility of special reinforced concrete moment-resisting frames under the influence of diverse seismic records. In this regard, the structures were initially designed using linear analysis based on the Iranian Standard 2800. They were then subjected to nonlinear analysis using ground motion records from soil type III with varying intensities. These records were extracted from the PEER database and standardized using the SeismoSignal software. In accordance with Standard 2800, the records were categorized into three sets of seven records each and scaled using a target spectrum and MATLAB software. Four-story and eight-story structures were analyzed using these records through nonlinear analysis, and the results were presented as performance curves. According to the guidelines of Iran's Publication No. 360, the nonlinear design of the structures was evaluated from two perspectives: the mean response of each record set and the individual response of each record. The results indicated that the average responses were within the permissible limits of the code, although in some specific records, the maximum rotations of beams and columns exceeded the allowable limits. Additionally, the inter-story drifts of the structures were generally within acceptable ranges, indicating good performance of the structures against seismic fragility.The collapse margin ratio was evaluated based on FEMA P695 requirements, which include incremental dynamic analysis, pushover (nonlinear static) analysis, and performance factor evaluations. The findings confirm that all safety and performance criteria were met and that the structures are in a desirable and acceptable condition. Moreover, the obtained reliability factor values are within acceptable ranges and in accordance with international standards, indicating the structures' reliability and stability against seismic effects.

کلیدواژه ها:

، special reinforced concrete moment-resisting frame ، incremental dynamic analysis ، pushover (nonlinear static) analysis ، performance factors ، collapse margin ratio