侗族木鼓楼底层构架抗震性能研究

Study on seismic performance of bottom frame of Dong nationality wooden drum tower

为研究侗族木结构鼓楼的抗震性能,依据一实例杉木结构鼓楼,取其底层木构架,设计并制作了两榀单跨杉木构架缩尺模型,通过低周往复水平荷载试验与有限元数值模拟,分析木构架的滞回性能、刚度退化规律、变形等力学性能,并从能量角度定量分析了木构架的耗能机制。结果表明:水平反复荷载作用下,木构架的滞回曲线呈反Z字形,有捏拢现象,滞回环面积逐渐增大,木构架耗能也随之增加;木构架抗侧刚度退化严重,且在加载初期退化速率快,至极限位移时,刚度仅为初始刚度的32%;木构架的变形能力较好,易整体倾斜,当柱顶水平位移达到20mm时,柱脚开始部分抬升及水平滑移,榫卯出现挤压与脱榫;木构架主要通过滞回耗能消耗能量,滞回耗能的最大耗能占比可达80%;榫头与卯口之间的摩擦系数越大,木构架的极限水平承载能力越大。

In order to study the seismic performance of Dong nationality wooden drum tower,based on an example of fir structure drum tower,taking its bottom frame,two single-span fir frame scale models were designed and manufactured.Through low-cycle reciprocating horizontal load test and finite element numerical simulation,the hysteretic performance,stiffness degradation law,deformation and other mechanical properties of the wooden frame were analyzed,and the energy dissipation mechanism of the wooden frame was quantitatively analyzed from the energy point of view.The results show that under the action of horizontal repeated load,the hysteresis curve of the wooden frame is in the shape of inverse Z,and there is pinching phenomenon.The area of hysteresis loop increases gradually,and the energy consumption of the wooden frame also increases.The lateral stiffness of the wooden frame is seriously degraded,and the degradation rate is fast at the initial stage of loading.When the ultimate displacement is reached,the stiffness is only 32%of the initial stiffness.The deformation capacity of the wooden frame is good,and it is easy to tilt as a whole.When the horizontal displacement of the top of the column reaches 20mm,the column foot begins to rise and slip horizontally,and the tenon and mortise appear extrusion and de-tenoning.The wooden frame mainly consumes energy through hysteretic energy,and the maximum energy consumption of hysteretic energy can reach 80%.The greater the friction coefficient between the tenon and the mortise,the greater the ultimate horizontal bearing capacity of the wooden frame.