FRP加固非延性钢筋混凝土框架结构的地震易损性分析与性能设计方法

Aiming at the extensive vulnerable existing nonductile reinforced concrete (RC) frames in China, in this project, the seismic fragility analysis of RC frame structures retrofitted with fiber-reinforced polymer (FRP) composites will be taken as a basic theoretical framework. Through the seismic damage investigation, numerical simulation and experimental verification, the principle of distinction and quantitative description for different seismic performance levels of RC frame strengthened with FRP is investigated and identified. Considering the earthquake randomness and the uncertainties of FRP material strength, the probabilistic seismic demand model for the seismic fragility analysis of whole structures is proposed. Based on the probabilistic safety assessment, the optimized retrofitting methods are systematically studied for RC frames with different heights, as well as different seismic performance levels. According to the analysis results, the conceptual design principle of FRP-retrofitted RC frame is developed. Moreover, the decomposition rules which separate the plastic storey displacements into the deformations of members including columns, beams and joints are studied and the relationship between the deformation of structural members and the amount of FRP retrofitting is proposed. Finally, the performance-based seismic retrofitting design method using FRP composites to improve the seismic performance of existing RC frame structures and to ensure the smallest global failure probability is set up. The goals of this project are to provide the evidences and decision supports for the revise of code for seismic design of buildings and code for strengthening concrete structures, and to provide the theoretical foundation for performance-based probabilistic seismic design and assessment based on global reliability.

本项目针对我国量大面广、且受灾严重的非延性钢筋混凝土框架结构，以FRP加固框架结构的地震易损性分析为切入点，通过震害分析、数值模拟和试验验证，研究加固后框架结构不同抗震性能水准的划分原则与量化描述方法，建立考虑地震动与FRP材料强度不确定性的概率地震需求模型，实现FRP加固框架结构不同性能水准下的地震易损性分析；依据易损性概率评定，系统研究不同高度、不同抗震性能水准下框架结构的FRP优化加固方法，提出FRP抗震加固框架结构的概念设计原则；研究框架结构层间位移分解为构件变形的解构规则，建立构件变形与FRP加固用量之间的关联，提出地震作用下钢筋混凝土框架结构整体抗震性能失效概率最小的FRP抗震加固性能设计方法。通过上述研究，为建筑抗震设计规范和混凝土结构加固规范的进一步修订提供参考依据和决策支持，为基于结构整体可靠度的概率抗震性能设计与评估方法提供理论基础。

本项目针对我国非延性或低延性现役钢筋混凝土（RC）框架结构，系统研究了FRP纤维增强复合材料加固RC框架结构的抗震性能、失效模式和设计方法，取得了如下研究成果：(1) 完成了FRP加固RC柱在双向水平荷载作用下拟静力，以及大比例柱的振动台试验，同时完成了带有楼板以及正交梁的框架角节点抗震性能试验，积累了丰富的试验数据，为后期构件与结构层面的精细化有限元分析和设计方法研究奠定基础；(2) 建立了FRP加固RC柱的精细化有限元模型和荷载—位移恢复力模型，提出了考虑节点核心区的FRP加固钢筋混凝土框架节点的宏单元模型，实现了FRP加固RC框架结构的整体抗震性能分析；(3) 完成了足尺FRP加固前后RC框架结构的振动台试验，进行了大量框架结构加固前后弹塑性静、动力有限元模拟分析，实现了FRP加固RC框架结构的易损性分析；(4) 依据我国旧抗震规范分别设计了五层、十层和十五层RC框架结构，以代表现役低层、中层和高层的低延性框架结构，基于极大似然估计算法，分析了FRP加固前后带有填充墙的不同高度框架结构的地震易损性，完成了不同加固方案下填充墙框架结构基于概率意义的抗震性能评定，最终给出了低层、中层和高层填充墙框架结构采用FRP抗震加固的概念设计原则；(5) 研究了不同结构特征参数及不同加固方案对填充墙框架结构的地震响应规律，建立了适用于我国规范的填充墙框架结构采用FRP加固前后的强度折减系数谱，给出了强度折减系数谱的简化表达式，提出了FRP抗震加固填充墙RC框架结构基于性态的能力谱方法。本项目研究成果，可为建筑抗震设计规范和混凝土结构加固规范的进一步修订提供了理论依据和决策支持，具有较好的理论意义和工程应用价值。