不同竖向荷载下“米字形”补间铺作抗震性能试验研究

EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF BUJIAN PUZUO IN THE SHAPE OF CROSS AND SALTIRE UNDER DIFFERENT VERTICAL LOADS

  • 摘要: 明晰古建筑木结构铺作节点的抗震性能,是了解古建筑木结构受力性能和安全状态的重要基础。为揭示不同竖向荷载下“米字形”补间铺作的抗震性能,以应县木塔三层明层东南向补间铺作为原型,制作2个1∶3.7的缩尺模型,进行了不同竖向荷载作用下补间铺作的拟静力荷载试验,分析了“米字形”补间铺作竖向荷载传递路径,研究了不同竖向荷载作用下补间铺作的破坏模式、滞回曲线、骨架曲线、耗能能力等抗震性能,重点关注了补间铺作各层构件内部的滑移和转动变形模式,研究了竖向荷载对其变形模式的影响。结果表明:不同竖向荷载下“米字形”补间铺作的变形模式和破坏特征基本一致。变形模式均为在正向加载时以转动变形为主,在负向加载时以构件间滑移变形为主,且滑移变形主要集中在“米字形”交叉构件层上部。增大竖向荷载会使产生主要滑移的构件层位置下移,也会使构件层间相对滑移量减少,同一加载级下滑移量可减少25%。破坏特征主要表现为斗类构件斗耳开裂甚至被剪掉。增大竖向荷载会提高试验铺作模型的水平承载力、初始刚度和耗能能力,竖向荷载增至3.7倍,水平荷载在正向和负向加载时分别提高至2.5倍和2.43倍,初始刚度提高至3.29倍,耗能能量增加至2.37倍。

     

    Abstract: Clarifying the seismic behavior of Puzuo joints in ancient wooden architectures is an important basis for understanding the mechanical performance and safety status of ancient wooden architecture. To explore the seismic performance of Bujian Puzuo in the shape of cross and saltire, the Bujian Puzuo in Yingxian Wooden Pagoda was taken as the prototype, and two 1∶3.7 scaled models were produced. Low cyclic-reversed loading experiments under different vertical loads were carried out. The loads transmission path of Bujian Puzuo in the shape of cross and saltire was analyzed, and the seismic behaviors, such as the failure modes, hysteretic curves, and skeleton curve energy dissipation capacity, were studied. In addition, the slip of the components in each layer of the Bujian Puzuo and rotation deformation modes were studied, and the influence of the vertical load on its deformation mode was studied. The results show that the deformation patterns and failure characteristics of Bujian Puzuo in the shape of cross and saltire under different vertical loads are basically the same. The deformation mainly includes the whole rotational deformation and the slip among components. The rotational deformation is the main deformation form under positive load, and the slip deformation among the components is the main form under negative load. The slip deformation is mainly concentrated on the upper part of the component layer in the shape of cross and saltire. When the vertical load is increased, the position of the component layer that produces the main sliding will be moved downward. In addition, increasing the vertical load will reduce the slip displacement between the upper and lower components, which can be reduced by 25% under the same loading level. The failure mode is mainly represented by the cracking or even shearing of Dou components. Increasing the vertical load has remarkable improvement on all Bujian Puzuo’s relative properties. When the vertical load is increased to 3.7 times, the load-carrying capacity under both positive and negative directions, initial stiffness and consumption of energy are increased by 2.5, 2.43, 3.29 and 2.37 times, respectively.

     

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