RC剪力墙拉-弯-剪受力机理及抗震设计方法研究

Under strong seismic motions, RC shear walls of high-rise buildings are probably subjected to axial tensile forces and in a critical tensile-bending-shear condition. This project will conduct a series of experimental tests on RC slender walls, moderate-aspect-ratio walls and squat walls subjected to axial tensile forces and lateral cyclic loads. The tensile-bending-shear behavior and seismic performance of RC walls will be investigated through those large-scale tests and in-depth theory analysis. This project will also develop a numerical model which can accurately capture the tensile-bending-shear nonlinear behavior of RC walls. Based on the test results and numerical simulation, this project will study the influence of key design parameters of RC walls to their seismic performance, including the tensile force amplitude, span-to-shear ratio, ratio of distributed rebars, ratio of boundary longitudinal rebars, etc. With those fundamental studies, this project targets to develop the seismic design method for the RC walls under tensile-bending-shear actions, propose the index and limiting value for the tensile forces acting on the RC walls, and recommend the details for improving the seismic behavior of tensile RC walls. The outcomes of the proposed research can contribute to development of the seismic design theory of RC walls and provide scientific support to the associated design codes and standards.

强震下高层建筑中RC剪力墙可能轴向受拉，出现拉-弯-剪受力的不利工况。本项目拟进行RC高墙、中高墙和矮墙在轴向拉力和水平往复力作用下的系列试验；通过大尺寸试验和理论分析，系统研究RC墙的拉-弯-剪破坏模式、受力机理和抗震性能；开发能准确模拟RC墙拉-弯-剪行为的非线性数值模型；通过试验和数值模拟，研究轴向拉力水平、剪跨比、分布钢筋配筋率、边缘构件纵筋配筋率等关键设计参数对RC墙拉-弯-剪抗震性能的影响规律。基于上述基础研究，提出RC墙拉-弯-剪抗震设计方法，提出RC墙轴向拉力水平控制参数和限值、以及改善其抗震性能的构造措施建议。研究成果可完善RC墙的抗震设计理论，并为相关规范和标准的制定提供科学依据。

钢筋混凝土（RC）剪力墙是高层建筑的主要抗侧力构件，强震下高层建筑中部分剪力墙可能轴向受拉，处于拉-弯-剪耦合受力的不利状态。本项目系统研究了RC剪力墙的拉-弯-剪受力机理和抗震性能，建立了高保真的数值模型，发展了相关抗震设计方法。项目的主要研究工作和成果包括4个方面。（1）系列试验：完成了系列大尺寸RC墙拟静力试验（4个大剪跨比墙试件、6个小剪跨比墙试件、4个中等剪跨比墙试件），研究了RC墙在轴向拉力和水平往复荷载下的破坏模式、滞回性能、承载力、有效刚度、变形能力等，揭示了RC墙在拉-弯-剪耦合受力下的变形特征。（2）理论分析：揭示了RC墙弯曲-滑移、剪切-滑移、弯曲-剪切等复杂破坏模式的力学机理，提出了RC墙的拉剪承载力理论模型；揭示了拉-弯受力下RC墙轴长的机理，提出了受拉RC墙轴向伸长的精细化计算模型和简化公式。（3）有限元模型：建立了基于实体单元的精细化有限元模型（LS-DYNA程序）和基于循环软化膜的有限元模型（OpenSees程序），可准确模拟RC墙在拉-弯-剪耦合受力下的非线性行为；通过参数分析研究了轴拉力、水平和竖向分布钢筋、边缘构件纵筋等对RC墙拉-弯-剪抗震性能的影响。（4）设计方法：校核了现行规范中RC墙正截面拉弯承载力和斜截面拉剪承载力计算公式，提出了改进的拉剪承载力计算公式，可合理考虑轴拉力和竖向钢筋对受剪承载力的影响；提出了基于竖向钢筋平均拉应力比的轴拉力控制指标及其限值。本项目研究成果完善了RC墙的抗震设计理论，可为相关规范和标准的制定提供科学依据，对保障高层建筑的地震安全有重要意义。