宋式带“昂”斗栱节点力学性能试验研究

Experimental study on mechanical properties of Song-style Dougong joints with Ang

古建筑中宋式斗栱节点最为显著的特征之一就是带有"下昂"。为研究具有这种特征的斗栱节点的受力性能,制作1∶3.52的缩尺模型试件进行竖向荷载试验和水平低周反复荷载试验,依据宋《营造法式》和实际建筑的"有昂无梁栿"和"有昂有梁栿"两种类型的宋式斗栱节点模型,设计并制作了以柱头斗栱节点为对象的试验模型。研究结果表明:在竖向荷载作用下,栌斗始终作为薄弱构件首先破坏;下昂与梁栿虽打断了斗栱节点分层叠加,但其依旧能保持良好的整体性;水平荷载作用下单个斗栱节点的倒三角形构造易发生转动,但加入梁栿后,节点的转动受到约束而发生滑移,此时斗栱表现良好的耗能效果,由此说明斗栱节点良好的抗震性能并非来自单个斗栱节点,而是由其通过相互约束协同工作而产生;底部暗销有较强的锚固作用,斗栱节点水平承载力主要由底部暗销的锚固力和柱与斗栱节点接触面的摩擦力组成。

One of the most significant features of the Song-style Dougong joints in ancient buildings is the so-called’Ang’.In order to study the mechanical properties of Dougong joints with this feature,vertical loading tests and horizontal low-cycle repeated loading tests were conducted on 1∶3.52 scale models.Two experimental models were made according to the official construction manual of Song Dynasty and real buildings to simulate two types of Songstyle Dougong joints at the top of column,namely,the’Ang with no beam’joints and the’Ang with beam’joints.The experimental result shows that the Ludou is always the first to be destroyed under different loads.Though the Ang and the beam disturbs the overlapping characteristic of the Dougong joints,they still maintain good integrity under the vertical loads.Under horizontal loads,the inverted triangles of individual Dougong joints are prone to rotation,but the additional beam greatly restricts the rotation of these joints,so that the whole Dougong joints can effectively slide and dissipate energy.This observation suggests that the good seismic performance of the Dougong joints does not come from a single Dougong joint,but is the result of mutual restraints and interaction of multiple joints.In an actual building,it is the Puzuo layer.The bottom hidden dowel has strong anchoring effect,and the horizontal bearing capacity of the Dougong joint consists of the anchoring force of the dowel and the frictional force at the interface between column and Dougong joints.