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

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.