主余震序列作用下RC框架结构累积损伤机理及性态设计方法

More than 85% mainshocks are followed by lots of aftershocks. The sequential excitation of mainshock-aftershocks will induce the significant cumulative damage to engineering structures. However, the current seismic design codes are all based on the single ‘design earthquake’ while ignoring the cumulative damage induced by mainshock-aftershock sequence. Next-Generation Performance-Based theory framework analyzes and designs structure with total probability theorem method. It can scientificly incorporate the cumulative damage and high uncertainty induced by mainshock-aftershock sequences. This project will perform the shake table test of reinforced concrete (RC) frame structure under the mainshock-aftershock sequences, and study the cumulative damage evolution process with test results and numerical simulation. The evaluation system on cumulative damage induced by mainshock-aftershock sequences will be built. The ability of residual displacement to represent the cumulative damage induced by mainshock-aftershock sequences will be investigated, and the influences of ground motion characteristics will be quantitatively studied. This project also aims to develop the evaluation theory and method for the structural fragility and economic loss of RC frame structure considering the cumulative damage induced by mainshock-aftershock sequences. The influences of aftershocks on the collapse safety margin and economic loss will be studied. This project finally will determine the acceptable design exceeding probability of RC frame structural damage and economic loss, and then propose the performance-based design methods considering the cumulative damage induced by mainshock-aftershock sequences. The project will provide reference and support to reveal the cumulative damage mechanism of structure under the mainshock aftershock sequence, and to improve the seismic design theory.

超过85%的主震均伴随大量余震，主余震序列作用对结构产生严重的累积损伤，现有抗震设计规范基于单次地震作用而无法考虑主余震序列作用。第二代性态理论框架基于全概率理论方法对结构进行分析和设计，能够科学地考虑主余震序列作用所造成的结构累积损伤和高不确定性。本项目将进行主余震序列作用下RC框架结构的振动台试验，结合数值模拟研究结构在主余震序列作用下的损伤演变过程，建立主余震序列所致累积损伤的评价体系，研究残余位移表征主余震序列所致累积损伤的能力，量化地震动特征的影响；发展考虑主余震序列所致累积损伤的RC框架结构易损性和经济损失评估理论及方法，研究余震对结构倒塌安全储备和经济损失的影响规律；确定主余震序列作用下RC框架结构破坏状态和经济损失的可接受设计超越概率，提出考虑主余震序列所致累积损伤的性态设计方法。本项目可为揭示主余震序列作用下结构损伤机制、完善抗震设计理论提供依据和理论支持。

地震统计表明，超过85%的主震均伴随大量余震，主余震序列作用对结构产生严重的累积损伤，现有抗震设计规范基于单次地震作用而无法考虑主余震序列作用。本项目在第二代性态理论框架内基于全概率理论研究了RC框架结构的累积损伤机理及性态设计方法。本项目基于全球真实主余震地震动，研究了RC框架结构在硬土场地、软土场地和近场主余震序列作用下的累积损伤反应，揭示了RC框架结构在主余震作用下的累积损伤机理，分析了余震地震动特征对结构残余位移的影响，建立了能够反映结构损伤与地震动特征之间关系的损伤谱；基于增量动力分析方法提出了主余震序列作用下结构易损性评估方法，研究了余震作用对结构直接经济损失、间接经济损失的影响，建立了考虑余震作用的地震经济损失评估模型；在对我国抗震设计谱进行修正的基础上，提出了考虑主余震效应的抗震设计谱，基于倒塌储备等效原则和考虑主余震的设计谱，提出了主余震序列作用下RC框架结构的抗震设计方法。本项目为揭示主余震序列作用下结构的累积损伤机制、经济损失估计、和完善抗震设计方法提供重要的理论依据和支持。本项目按照预期目标圆满完成了针对主余震序列作用的结构累积损伤机理、易损性评估和性态设计方法。