Seismic Vulnerability Analysis Of RC Frame Structures With Different Performance Levels

The performance-based seismic design theory is a new concept in the civilengineering field since1990s. Much attention has been paid to study it. Aiming atimproving the target performance level of structures, the theory requires that theperformance of structures designed should be predictable under the coming earthquake.In China, the study is relatively enough but practical application is still at initial stage atpresent. Therefore, expanding the performance-based structural design work and toresearch the seismic vulnerability of structures with different performance levels haveimportant theoretical significance and practical value.In this paper,3floors and7floors RC frame structures have been designedaccording to current Code for seismic design of buildings in China, which recommendsa reference method for seismic performance design. The author also designsconventional structures for the comparative analysis. All of the structures are located inzone where fortification intensity is7. Intermediate axis RC plane frame of structureshas been selected as the analysis object which was modelled by OpenSEES software.And ground motion records have been selected for incremental dynamic analysis. Theresults of IDA have been used for preliminary evaluation of the structures. According tothe conclusions of IDA, three types of records have been selected for structural failuremode analysis. Finally, the structural vulnerability curve and Collapse Margin Ratio(CMR) obtained through structural vulnerability analysis has been used for making areasonable assessment of the structures.This paper shows that different ground motion record input will lead to differentstructural collapse failure mode. Higher seismic performance requires higherperformance level of structure. Known by the structural vulnerability analysis, structurewith a higher performance level has a smaller probability of exceeding the limit statespecified in this paper; structure with a higher performance level has a larger CMRvalue. And the CMR values of3floors structures are larger than7floors structures atthe same performance level. The collapse probability of all structures under rareearthquake is less than1%, which can meet the requirement that is "no crash in rareearthquake" in ATC code, strucutures designed due to level1and level2have a smallercollapse probability than structures designed by other levels when all of them are undergreat earthquake, the former has a better collapse resistant capability.