考虑失效路径随机演化的钢筋混凝土框架结构整体抗震可靠度研究

To overcome the difficulties of the traditional system reliability theory of structures, in this project, a viewpoint of physical random systems will be taken as a basic theoretical framework for the research. A fully non-stationary physical random process model will be developed for earthquake strong motions with consideration of both temporal and spectral nonstationarities. The reinforced concrete frame structures are taken as test-beds. Through the damage investigation, numerical simulation and experimental verification, the evolution pattern of failure paths and collapse failure modes of RC frame structures are investigated. Considering the random evolution phenomenon of failure paths during the process of failure modes formation, the most likely failure modes of structures and their corresponding severest critical earthquake action are sought using nonlinear finite element reliability methods, and the probability evolution laws of structural failure paths are studied by use of generalized probability density evolution theory. On the basis of the above research, considering the multiple failure criteria and multi-level performance objectives, the limit state equations for global load-carrying capacity, global deformation capacity, global seismic damage, and global progressive collapse of structures are set up, and the global seismic reliability for RC frame structures are systematically and thoroughly studied. The goals of this project are to provide reference frame for optimization and control of structural failure modes, to provide technical support for the research on robustness and resilience of structures under strong earthquakes, and to provide the theoretical foundation for performance-based seismic design based on global reliability.

为克服传统结构体系可靠度理论存在的困难，从"物理随机系统"的观点出发，建立强度与频率非平稳的地震动物理随机过程模型及其时域模拟方法；以钢筋混凝土框架结构为载体，通过震害分析、数值模拟和试验验证，研究其在强震作用下失效路径的演化规律以及倒塌破坏模式；针对结构地震失效模式形成过程中失效路径的随机演化现象，采用非线性有限元可靠度方法研究结构的最可能失效模式及最不利地震作用，采用广义概率密度演化理论研究结构失效路径的概率密度演化规律；在此基础上，考虑结构的多种破坏准则和多水准性能目标，建立结构的整体承载能力、整体变形能力、整体地震损伤和整体连续倒塌极限状态方程，深入开展考虑失效路径随机演化的钢筋混凝土框架结构整体抗震可靠度研究，以其为研究结构失效模式优化与控制问题提供参考依据，为研究结构的鲁棒性和可恢复性理论提供技术支持，为研究基于整体可靠度的概率抗震性能设计提供理论基础。

近年来结构整体可靠度理论受到了国内外学者广泛重视，为解决当前结构整体抗震可靠度理论中存在的问题，本项目以钢筋混凝土框架结构为载体，通过数值模拟和试验验证，研究钢混框架结构在强震作用下失效路径的演化过程以及局部和整体倒塌失效模式。分别从基本变量模型和综合变量模型角度，研究结构地震失效模式形成过程中失效路径的随机演化现象。在此基础上，考虑结构的多种破坏准则和抗震性能设计理论的多水准性能目标，分别建立结构的整体承载能力极限状态、整体变形能力极限状态和整体地震损伤极限状态方程。考虑结构构件的压弯失效和剪切失效，建立考虑多重失效模式的结构整体侧向倒塌和连续倒塌极限状态方程，深入开展考虑失效路径随机演化的钢筋混凝土框架结构在多种破坏准则和多重失效模式下的整体抗震可靠度研究。通过四年时间取得了以下研究成果：1) 建立新的强度与频率非平稳地震动物理随机过程模型，给出其物理参数预测模型；2) 提出地震动随机过程基于随机脉冲序列线性滤波的时域模拟法，生成四类场地的系列人工地震动记录；3) 建立同时考虑构件强度和刚度退化、节点影响、楼板影响、填充墙影响等多种复杂因素的钢筋混凝土框架结构精细化非线性有限元模型；4) 提出钢筋混凝土框架结构整体承载能力极限状态、整体变形能力极限状态、整体累积损伤极限状态、整体连续倒塌极限状态的非线性抗震可靠度分析方法；5) 开发有限元可视化模拟软件 DONAP-OpenSeesGUI可靠度分析程序。本项目为研究大型复杂结构的失效模式优化与控制问题提供参考依据，为研究结构的鲁棒性和可恢复性理论提供技术支持，为研究新一代基于性能的地震工程理论和基于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。