An Equivalent Frame Model for Seismic Analysis of Existing Masonry Building

Collapse safety is the most important objective of performance-based seismic design. Buildings should have enough safety margin to avoid collapse during severe or mega earthquake. However, current Chinese seismic design code does not have explicit design specification or quantitative evaluation for collapse-resistant capacity. Take a two-story masonry building as an example, an equivalent frame model for pushover and incremental dynamic analysis are established, and the comparison are also studied. In addition, the fragility curves can also be obtained. The analysis results show that the results of plastic hinge mainly appear in ground floor wall between windows and doors. Moreover, the analysis result has good uniformity with seismic damage. Judging from the failure mechanism, pushover and incremental dynamic analysis have very good similarity. In addition, they show elastic deformation is very small and brittleness is very apparent of the masonry building. Seismic vulnerability analysis shows that the significant damage and the near collapse curves are very close to each other. This mean that, once the significant damage limit state is reached,only small PGA increments are need for reaching the near collapse limit state.