装配整体式剪力墙结构动力特性研究

Dynamic characteristics of a monolithic precast concrete shear wall structure

根据相似理论,基于质量系统量纲推导了动力系统中各物理量的相似关系,并确定合适的相似常数。对12层剪力墙结构拆分,设计了模型材料配合比和模型结构预制墙板及连接技术方案,制作了一个1:5装配整体式剪力墙结构(MPCS)和一个现浇剪力墙结构(CIPS);通过振动台试验对比研究了装配整体式剪力墙结构的破坏形态、动力特性参数。结果表明:装配整体式剪力墙结构的裂缝形态及扩展顺序不同于现浇剪力墙结构,预制墙板上下接触面的水平裂缝为主要损伤形态之一,连梁端部形成塑性铰后,最终微裂缝形成于MPCS预制墙板的竖向连接部位结合面,而CIPS为剪力墙墙肢;连接部位接触面微裂缝的发展使MPCS的初始刚度和主频率较CIPS的下降明显;两模型结构阻尼比随加速度峰值增大而增大,变化范围为4. 2%～8. 2%;一阶振型曲线近似为"弯曲"型,随PGA增大逐渐外凸,且现浇结构在塑性阶段外凸更明显,而二阶振型相似。

Here,according to the similarity theory,similar relations of physical quantities in a dynamic system were deduced based on a mass system dimensions and appropriate similar constants were determined.A12-story shear wall structure was disassembled,and its model material mix ratio and the model structure’s precast wall plates and connection technique were designed to construct a1∶5scaled monolithic precast concrete shear wall(MPCS)structure model and a cast-in-place shear wall(CIPS)one.The failure forms and dynamic characteristics of MPCS and CIPS structure models were contrastively studied with shaking table tests.The results showed that MPCS’s crack forms and their expansion sequence are different from those of CIPS;horizontal cracks in the upper and lower contact surfaces between precast wall plates are one of MPCS’s main damage forms;After connected beams’ends form a plastic hinge,final micro-cracks form at the vertical connection joint surface of MPCS precast wall plates,while those form at the wall limb of CIPS;the micro-cracks at connection contact surface between precast wall plates cause MPCS’s initial stiffness and main frequency to drop more obviously than CIPS’s do;structural damping ratios of both two models increase with increase in PGA,their variation range is4.2to8.2%;the first order vibration shape curve of MPCS is approximated as a"bending"type and gradually becomes outward convex with increase in PGA,and that of CIPS becomes more obvious than MPCS’s does in plastic stage;the second order vibration shape curves of both two models are similar.