基于性能的城市建筑群震害预测方法研究

The earthquake damage prediction works for urban buildings in China were mainly brought out using empirical methods, which were derived from historical earthquake damages, and followed by the results with seismic intensity. However, without taking fully considerations of the complexity of earthquake ground motion, the evaluation results of seismic zonation could not be directly adopted, which restricted the development of earthquake damage prediction works. A new performance-based earthquake damage prediction method for urban building groups is proposed in this project, which is focus on reinforced concrete (RC) frame structures. The empirical fragility curves of RC frame functioned with ground motion can be gotten by using earthquake damage data of Wenchuan earthquake. Seismic design level for Chinese buildings can be classified by factors such as construction year, seismic fortification intensity, and story numbers. Seismic performance level and quantitative index of each level are rationally defined. Considering the randomness of structural parameters and uncertainties of ground motion, through the increment dynamic analysis (IDA), probabilistic seismic demand model of structure are determined. Then, fragility curves functioned with ground motion can be derived and calibrated by actual earthquake damages. Finally, standardized model database for fragility curves of structures with different seismic design levels can be established. And the characteristics of different cities are considered, a standardized performance-based earthquake damage prediction method for urban building groups suitable for China is proposed according to seismic hazard analysis results and earthquake loss estimation models, which would provide theoretical basis of urban seismic disaster planning and emergency response pre-arranged planning for different governments at all levels.

我国城市建筑物震害预测多以基于历史震害的经验分析方法为主，结果多以地震烈度为指标，对地震动的复杂性考虑不足，无法直接应用地震区划的评价结果，制约了震害预测工作的发展。本项目以城市量大面广的钢筋混凝土框架结构为研究对象，研究基于性能的建筑物群体震害预测方法。利用汶川地震震害资料建立以地震动为变量的经验易损性曲线。根据建造年代、抗震设防烈度和层数等因素给出结构的抗震设防水平分类标准。确定合理的结构抗震性能水准和量化指标。考虑结构参数的随机性和地震动的不确定性，通过增量动力分析确定结构的概率地震需求模型，建立以地震动参数为变量的地震易损性曲线，并与实际震害对比验证。构建不同抗震设防水平的结构易损性曲线标准模型库，根据地震危险性分析结果和地震损失评估模型，考虑各城市差异性提出适合我国国情的基于性能的城市建筑群震害预测标准化方法，可为各级政府进行城市抗震防灾规划、地震应急预案制定等提供理论依据。

针对我国城市不同龄期建筑并存等特点，且已有的易损性分析方法和结果难以满足实际需求，项目组提出了基于性能的建筑物群体震害预测新方法。该方法将城市房屋建筑分为两大类：设防建筑和不设防建筑。其中，（1）不设防建筑主要包括土木、砖木、自建砖混结构等，其地震易损性可以根据已有震害资料统计获得。（2）设防建筑主要包括多层约束砌体结构房屋、多层和高层钢筋混凝土结构房屋等根据抗震设计规范设计和施工的标准房屋。根据经验，在场地条件和抗震设防标准相同的情况下，不同城市的同类房屋的抗震能力和地震易损性是相同的。对于设防建筑，基于实验研究和数值分析构建不同抗震设防水平的设防建筑地震易损性标准样本库，未来各城市或区域进行震害预测时无需重复繁琐的分析工作，只需根据建筑抗震设防水平直接从样本库中获取，为未来我国各城市开展快速有效的震害预测工作做好铺垫。为此，项目组开展的主要工作和取得的主要成果包括：（1）基于汶川地震、玉树地震等震害资料总结分析了各类房屋建筑典型震害特征和震害原因，收集了大量地震中受损建筑的脉动测试数据，可为数值模拟和实验研究提供基础资料和验证依据。（2）针对南北地震带房屋建筑种类众多、易损性差异大等特点，提出采用不同分级和分区域的精细化方法来研究南北地震带房屋建筑地震易损性的方法。（3）通过框架柱、框架梁等构件的低周反复加载试验，以及整体结构的IDA分析，提出了基于性态的RC框架结构损伤评价方法，建立了构件震损现象-构件震损程度及分布-整体震损程度的关联关系。（4）提出考虑建造年代、抗震设防烈度和层数等不同因素的建筑物抗震设防水平分类标准；研究建立合理的地震动记录的选取和缩放方法以及考虑填充墙和楼板影响的结构精细化建模方法，并与实际震害对比验证模型合理性。考虑结构参数的不确定性和地震动的不确定性，通过IDA分析建立以地震动参数为变量的不同抗震设防水平的RC框架结构地震易损性曲线。