塑性铰区加强方式对高强混凝土剪力墙抗震性能的影响

Effects of strengthening methods in plastic hinge zone on seismic performance of high-strength concrete shear walls

为研究塑性铰区加强方式对高强混凝土剪力墙抗震性能的影响,首先,开展4片高强钢筋高强混凝土剪力墙的低周反复荷载试验与ABAQUS有限元模拟;其次,分析塑性铰区采用添加钢纤维、加密箍筋、外包钢板3种加强方式对剪力墙破坏形态、滞回特性、承载力与变形能力、强度与刚度退化、耗能能力以及塑性铰发展长度等方面的影响机理;最后,提出适用于高强钢筋高强混凝土剪力墙的等效塑性铰长度与承载力计算方法。研究结果表明:3种加强方式均有利于减轻墙体损伤程度,降低剪切变形占比,提高变形与耗能能力;当3种方式加强段高度相同时,添加钢纤维的方式对墙体破坏形态作用最明显;墙底部外包合理厚度的钢板可以使墙体塑性铰充分发展,形成双塑性铰区,从而使试件峰值荷载提高17.7%、极限位移角提高75.0%。基于简化的曲率分布与塑性变形基本假定,考虑力的平衡关系、弯曲与剪切变形的协调关系,本文提出的等效塑性铰长度计算方法与水平承载力计算方法精度较高。

To investigate the effects of plastic hinge zone reinforcement methods on the seismic performance of high-strength concrete shear walls, firstly, four high-strength concrete shear walls with high-strength reinforcements were designed to carry out low-cycle loading tests and ABAQUS finite element analysis. Secondly, the effects of three reinforcement methods with adding steel fibers, adding stirrups, and wrapping steel plates on the failure modes, hysteretic behavior, load-bearing and deformation capacity, strength and stiffness degradation, deformability, energy dissipation capacity, and the development length of plastic hinge zone for shear walls were evaluated. Finally, the equivalent plastic hinge length calculation method and bearing capacity calculation method applicable to high-strength concrete shear walls with high-strength reinforcements were proposed. The results show that the three strengthening forms effectively reduce the degree of wall damage, diminish the proportion of shear deformation, and improve the wall's deformation and energy consumption capability. When the heights of the strengthening sections in the three methods are equal, the addition of steel fibers is the most effective in improving the damage pattern of the wall. A fitting thickness of steel plate at the wall base can make the plastic hinge zone fully develop and form the double plastic hinges, significantly enhance the peak load by 17.7%, and the ultimate drift ratio by 75.0%. Based on the simplified curvature distribution and basic assumptions of plastic deformation, considering the balance of force relationship, and the bending and shear deformation coordination relationship, the proposed methods for calculating the equivalent plastic hinge length and horizontal bearing capacity show a high level of precision.