Abstract

Concrete buildings reinforced by plain bars are one of the special types of old structures generally built before the 1970s. According to the experiences of earthquakes and experimental tests, the dominant damage mode in these structures includes a deep crack at the intersection of the beam with the joint panel zone. In this study, seismic fragility curves of existing concrete buildings reinforced by plain bars were investigated by means of incremental dynamic analysis and by consideration of soil-type effects and construction quality effects. A relatively simple and efficient non-linear model based on the experimental behaviour of exterior and interior joints of the represented building is used to simulate pre- and post-elastic behaviour of the joints which fail under bar slippage mode. Two record sets were considered corresponding to the soil types C and D of the NEHRP provision. The results indicated that the seismic vulnerability of the represented building increases at all damage states as the type of soil changes from C to D. On average, the median capacity of the building is decreased by about 30% for the moderate limit state as the type of soil changes from C to D. Also, the normal distribution function with median data is the best distribution function for seismic fragility assessment of the represented building.

摘要

普通钢筋混凝土建筑是1970年代以前普遍建造的特殊类型的旧结构之一。根据地震和试验试验的经验，这些结构的主要破坏模式包括梁与连接面板区域相交处的深裂缝。本研究采用增量动力分析的方法，考虑土型效应和施工质量效应，研究了现有素钢筋混凝土建筑的抗震脆性曲线。基于所代表建筑物的外部和内部节点的实验行为，一个相对简单和有效的非线性模型被用来模拟在杆滑动模式下失效的节点的预弹性和后弹性行为。两个记录集被认为对应于 NEHRP 规定的土壤类型 C 和 D。结果表明，随着土壤类型从C到D的变化，所代表建筑物的地震易损性在所有破坏状态下都增加。平均而言，在中等极限状态下，建筑物的中值容量降低了约30%。土从 C 到 D 的变化。此外，具有中值数据的正态分布函数是代表建筑物地震脆弱性评估的最佳分布函数。