双轴地震作用下RC带翼缘剪力墙破坏机理与计算模型研究

Under biaxial earthquake action, coupling effect exists between the loading directions of the three-dimensional shear walls with flange. But at present, the research on its seismic behavior under the influence of biaxial coupling effect is scarce, the performance degradation index and analytical model have not been established as well. To solve this problem, the damage evolution, hysteretic behavior and failure mechanism of RC shear walls with flange subjected to biaxial loading are studied through model test, numerical simulation and theoretical analysis. Based on the model test, the qualitative description and quantitative index of such component under different damage states are given, the failure criterion and analytical model considering the biaxial coupling effect is then established. Through numerical simulation, the effect of biaxial earthquake action on shear lag effect is studied, on which the calculation methods of effective flange width and bearing capacity for normal section of RC shear wall with flange under the influence of biaxial coupling effect are established. Through analyzing the variation of each deformation component along loading process, a method for calculating the deformation capacity of RC shear walls with flange under the influence of biaxial coupling effect is proposed. This project not only extends the research on RC shear wall with flange from uniaxial to multidimensional level, but also provide reference and technical support for the seismic design of such component under biaxial earthquake action.

双轴地震作用下，作为空间受力构件的带翼缘剪力墙各加载方向间存在耦合作用，但目前对其双轴耦合效应影响下抗震性能的研究较少，且未建立起相应的性能劣化指标和计算模型。针对此问题，本项目采用试验研究、数值模拟与理论分析相结合的方法，研究RC带翼缘剪力墙在双轴水平地震作用下的损伤演化、滞回性能和破坏机理，确定此类构件不同损伤状态的定性描述和量化指标，建立考虑双轴耦合效应的失效破坏准则和计算模型；研究双轴地震作用对剪力滞后效应的影响，建立双轴耦合效应影响下RC带翼缘剪力墙有效翼缘宽度和正截面承载力计算方法；揭示双轴地震作用下RC带翼缘剪力墙的各变形分量在受力过程中的变化规律，建立考虑双轴耦合效应的截面变形能力计算方法。本项目将RC带翼缘剪力墙的研究从单轴拓展至多维层面，可为双轴地震作用下此类构件的抗震设计提供基础资料和技术支撑。

作为空间受力构件的带翼缘剪力墙，其在多维地震作用下各加载方向间存在耦合作用，并会影响带翼缘剪力墙原有的损伤机制和抗震性能。本项目以研究双轴地震作用下RC带翼缘剪力墙的抗震机理与计算模型为目标，首先开展了不同双轴加载制度下RC带翼缘剪力墙的拟静力试验，研究了带翼缘剪力墙在双轴荷载作用下的损伤演化过程和破坏机理，量化了双轴耦合效应对剪力墙各受力方向抗震性能的影响，并基于PIV技术揭示了双轴荷载作用下剪力墙弯曲、剪切以及滑移变形的发展规律。结果表明：双轴耦合受力产生的内力重分布和局部附加应力会改变带翼缘剪力墙的局部受力机理，加速了剪力墙的开裂和损伤，削弱了各受力方向的承载力、延性和耗能能力，并增大了弯曲变形占比和剪力滞后效应。其次，通过RC带翼缘剪力墙的精细化数值模拟，揭示了带翼缘剪力墙剪滞效应的发展规律，量化了不同参数对剪滞效应的影响，基于变分原理推导了带翼缘剪力墙有效翼缘宽度的弹性解析解，建立了极限状态下有效翼缘宽度的简化计算方法，提出了考虑双轴耦合效应影响的正截面承载力计算模型。最后，通过对带翼缘剪力墙截面曲率和塑性铰长度的变参数分析，建立了异形截面剪力墙截面曲率和塑性铰长度的计算方法，提出了一种考虑弯曲、剪切和纵筋滑移贡献的RC带翼缘剪力墙变形能力计算模型。项目研究成果对双轴地震作用下RC带翼缘剪力墙的抗震设计和性能评估具有重要的参考价值。