不同剪跨比下低矮开洞剪力墙抗震性能试验

Seismic behavior of low-rise shear walls with different shear span ratios

核电厂房的剪力墙具有剪跨比低和配筋率高的特点,为满足人员通行以及设备管道的布置,需要在剪力墙中开设洞口,然而,关于低矮开洞剪力墙抗震性能的研究比较有限。为此,设计3个1∶2.7的大比例尺低矮钢筋混凝土剪力墙试件,通过拟静力试验研究剪跨比对此类剪力墙抗震性能的影响。研究内容包括试件的破坏模式、滞回曲线、延性系数、刚度退化、耗能能力和变形能力等方面的分析和讨论。结果表明:低矮开洞剪力墙的破坏主要是由墙肢的斜向主裂缝宽度明显增大引起,导致承载力快速下降;剪跨比的减少使得低矮剪力墙的承载力、刚度和单圈耗能效果增加,但变形能力和极限位移显著降低,从而导致累计耗能较小;剪跨比较小的试件容易在洞口上方产生塑性铰,随后连梁的转动会导致洞口附近的混凝土压碎,且剪切效应较显著。此外,小洞口的存在会产生严重的不对称性,影响其抗震性能。

The reinforced concrete shear walls of nuclear power plants have a low shear span ratio and high reinforcement ratio.Multiple openings are required to allow for the introduction of doors and pipelines into the building.However,research on the seismic performance of low-rise shear walls with openings is relatively limited.Therefore,three 1∶2.7 squat reinforced concrete shear walls were experimentally investigated through quasi-static testing to analyze the impact of shear span ratio on seismic performance.The study included analysis and discussion of the failure mode,hysteresis curves,ductility coefficients,stiffness degradation,energy dissipation capacity,and deformation capacity of the specimens.The results indicated that the failure in low-rise shear walls was primarily caused by the significant increase in the width of diagonal principal cracks in the wall legs,leading to a rapid decrease in bearing capacity.Furthermore,reducing the shear span ratio increased the bearing capacity,stiffness,and energy dissipation of low-rise shear walls,but significantly reduced their deformation capacity and ultimate displacement,resulting in lower cumulative energy dissipation.Specimens with smaller shear span ratios were prone to develop plastic hinges above the openings,and subsequent beam rotation caused concrete crushing near the openings,with significant shear effects.Moreover,the presence of small openings resulted in severe asymmetry,affecting the seismic performance of the shear walls.