近场强震下齿槽拼缝预应力装配耗能剪力墙的工作机理和易损性分析

Higher structural ductility and strength capacity are required in the near-fault strong earthquake, but relevant researches on precast concrete structures are few. A new prestressed precast energy dissipated shear wall with cogging connection is proposed in the project to deal with failure modes including excessive lateral deformation, slit slip, failure of prestressed tendons and local failure of bottom edge members, etc., which can be observed in the prestressed precast concrete shear wall in the near-fault strong earthquake. The proposed precast shear wall with cogging connection is assembled via prestressed tendons running across the tenons in bottom shear wall and cogging at the base. Energy dissipation bars restrained by thin-walled tubes are embedded in edge members across the connection. Firstly, the bending-shear decoupling working mechanism, characteristic as concrete cogging resisting shear and edge members of the shear wall resisting bending, will be verified via experimental and numerical analyses. Then, the configuration of the tenons and cogging will be optimized. A secondary stiffness will be provided in the proposed shear wall due to the shift of the point of resultant force (contact point) under the large deformation, which results in the formation of two-phase mechanical characteristics and helps the establishment of the high-efficiency calculation model. Besides, design methods of the energy dissipation bar restrained by thin-walled tube will be determined and the simplified simulation method will be provided through tests on the bottom of edge members of the shear wall. Finally, performance requirements of the proposed shear wall under the near-fault strong earthquake velocity pulse will be studied based on the high-efficiency calculation model obtained from theoretical and experimental analyses. The safety tolerance of the shear wall will be evaluated and uncertainties of the earthquake will be fulfilled via a large amount of time-history analyses.

近场强震下结构有着更高的延性和承载力需求，而装配式混凝土结构的相关研究较少。项目基于近场强震下预应力装配式混凝土剪力墙可能存在的侧移过大、拼缝滑移、预应力筋失效以及边缘区底部失效等破坏模式，提出了新型齿槽拼缝预应力装配耗能剪力墙，主要由底层墙板端部齿榫及基础齿槽通过后张无粘结预应力筋张拉锚固，拼缝边缘区内置薄壁套管耗能筋。首先，通过有限元和试验结合确认混凝土齿槽抗剪、剪力墙边缘构件抗弯的弯剪解耦工作机制；其次，优化齿槽拼缝折面形态，使得在大变形下齿槽拼缝外侧面接触，合力点外移，为剪力墙提供次生刚度，形成齿槽拼缝两阶段受力特性，建立其高效分析模型；再次，通过剪力墙边缘区底部局部试验，研究内置薄壁套筒耗能筋设计方案，给出剪力墙边缘区底部的简化模拟方法；最后，基于理论和试验得到的高效分析模型，研究近场强震速度脉冲特性对新型剪力墙结构性能需求，通过大量时程分析模拟地震不确定性，评估剪力墙安全裕度。

强震或序列强震作用下装配式剪力墙有着更高的延性、消能和震后可修复的需求，但是相关研究较少。项目围绕剪力墙耗能元件失效模式、设计方法和检修技术，震后预应力筋的易更换，序列强震作用下剪力墙拼缝的工作机制等四个方面开展了理论、试验和设计方法研究。共发表高水平英文论文14篇，完成专著2本，授权发明专利6项，培养研究生6人，参与获得中冶集团科学技术一等奖等，主要工作如下：.(1)建立了剪力墙外置消能杆的内核消能段疲劳断裂和内核外伸段无约束区域的压弯失效两种失效模式，提出了消能杆内核外伸段压弯失效的变形模式，基于弹塑性屈曲理论建立了消能杆内核外伸段的力学模型，给出了弹塑性状态下无约束段的屈曲临界力的计算方法。.(2)提出了具有断裂监测功能的消能杆设计思路，消能杆的一端设有销钉，端部销钉将在内核颈缩或者断裂后受剪破坏。分析了断裂预警机制，确定了相关尺寸参数的取值范围，通过试验验证了断裂监测机制的可行性。.(3)强震作用下预应力装配式剪力墙中的预应力筋可能屈服或破损。为了方便预应力筋更换，并提高预应力筋利用效率，提出了仅在装配式剪力墙下部布置后张无粘结预应力筋的新型局部预应力装配式剪力墙(LPPW)，试验表明LPPW具有稳定的滞回性能和良好的自复位能力，混凝土墙板和预应力筋均处于弹性状态。.(4)为了实现剪力墙结构强震及序列强震作用后快速恢复，以LPPW为研究对象开展序列荷载作用下拟静力试验，对比了LPPW在序列加载下的抗震性能，验证了更换预应力筋和耗能杆来实现LPPW快速修复的可行性，在此基础上建立了装配式剪力墙拼缝的工作机制。.上述研究不仅促进了预应力装配式剪力墙的性能提升，而且消能杆设计理论和方法，将有助于促进其在高性能装配式混凝土结构的应用。