砌体结构的地震易损性研究

The research of seismic vulnerability of masonry building

建筑结构的抗地震倒塌能力是抗震性能化设计的核心目标。建筑结构需要足够的抗倒塌安全储备,以避免大震或超大震的倒塌破坏。我国现行抗震设计尚缺乏大震抗倒塌定量设计方法和抗地震倒塌能力的定量评价指标。采用等效框架方法,以一幢2层的砌体结构民房为例,对其进行了Pushover和IDA分析,并对其进行了比较,最后获得了结构的易损曲线。结果表明,结果的塑性铰主要出现在底层窗间墙和窗下墙被存在的洞口削弱的部位,这一点与地震中砌体结构的破坏具有较好的一致性,从破坏机制来看,Pushover和IDA分析具有很好的相似性,且砌体结构脆性非常明显;结构易损性分析表明,结构的严重破坏和倒塌两条曲线相隔非常近,这就意味着当砌体结构为严重破坏时,就非常容易倒塌。

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, the Pushover and IDA analysis are studied used by the equivalent frame, and the comparison are also studied. In addition ,the fragility curves can be obtained. The analysis results show that the results of plastic hinge mainly appear in ground floor wall between windows and doors. The analysis result has good uniformity with seismic damage. Judging from the failure mechanism, Pushover and IDA analysis have very good similarity. In addition, they show elastic deformation is very small and brittleness is very apparent of the masonry building. Structure 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.