中等剪跨比RC剪力墙拉-弯-剪受力性能试验研究

为研究中等剪跨比钢筋混凝土(RC)剪力墙的拉-弯-剪受力性能，对4个RC剪力墙开展了在恒定轴拉力和往复水平力作用下的拟静力试验。RC墙剪跨比为1.5，尺寸和配筋均相同，仅轴拉力变化。结果表明：RC墙分别发生了剪切破坏、弯曲-剪切破坏和弯曲破坏；轴拉力致使RC墙的水平承载力降低，竖向钢筋平均拉应力比ns从0.20增大到0.80时，RC墙峰值荷载降低了约55%；中等剪跨比RC墙弯曲-剪切耦合效应明显，墙底部截面弯曲屈服后，塑性铰区的剪切变形也表现出显著的非线性；轴拉力和往复水平力作用下墙体发生显著的轴向伸长，引起墙体受剪承载力退化，竖向钢筋平均拉应力比ns=0.40的RC墙，其受力由弯曲机制向剪切机制转变，出现了弯曲-剪切破坏，基于转动角软化桁架模型和轴向伸长的实测数据，定量计算了该类墙体的受剪承载力退化，揭示了弯曲-剪切破坏机理。最后，验证了美国ACI 318—14和中国JGJ 3—2010中RC墙正截面拉弯承载力计算方法和公式的适用性。

Experimental study on axial tension-flexure-shear behavior of moderate-aspect-ratio RC shear walls

To investigate the axial tension-flexure-shear behavior of moderate-aspect-ratio reinforced concrete (RC) walls, quasi-static tests were conducted on four RC shear wall specimens subjected to axial tension force and lateral cyclic loadings. All specimens had a shear-to-span ratio of 1.5, and their geometric dimensions and reinforcement details were identical. The test variable was the tension force applied to the walls. Various failure modes, including shear failure, flexural-shear failure and flexural failure are observed for the specimens. The axial tensile force is found to significantly influence the lateral strength capacity of RC wall specimens. The maximum lateral strength decreases by 55% when the normalized tensile stress of vertical reinforcement ns increases from 0.20 to 0.80. Shear flexure interaction is observed for the moderate-aspect-ratio wall specimens, where the inelastic flexural deformations of walls lead to inelastic shear deformations developed in plastic hinge region. Significant axial elongation is observed for the wall specimens subjected to combined axial tension and lateral cyclic loading. The axial elongation would result in degradation of shear strength capacity of walls, and consequently lead to the failure mechanism transition from flexural mode to shear mode for the wall specimen with ns=0.40. Using the rotating-angle softened truss model and measured data of axial elongation, the shear strength degradation of the wall specimen was estimated and the flexural-shear failure mechanism was illustrated. Finally, the design method and formulae of tension-flexure strength of RC walls specified in U.S. code ACI 318-14 and Chinese standard JGJ 3—2010 were calibrated with test data