Study On Seismic Mechanism Of Side Span Half Tenon Joint In Ancient Chinese Wooden Buildings

The ancient Chinese wooden building is a treasure in the history of world architecture,but in its long life cycle,environmental and human factors have brought various forms of damage to ancient Chinese wooden building.Damaged ancient Chinese wooden building tend to be partially damaged or even collapsed under earthquake loads.After investigation,it was found that the ancient Chinese wooden building was damaged by the tenon-and-mortise joints due to earthquake disasters.Therefore,the reinforcement and repair of the mortise and tenon joints of ancient Chinese wooden building can well avoid the damage of the overall structure.The reinforcement and repair of the mortise and tenon joints under the action of seismic loads often rely on the study of the seismic mechanism of these joints.At present,scholars have carried out theoretical analysis,finite element analysis and experimental analysis on the seismic mechanism of through tenon,straight tenon and dovetail joint.However,after investigation,it is found that the pull-out resistance of the side span half tenon joint is weak,and it is prone to local damage under the earthquake load.However,there are many experimental studies on this kind of joint,and theoretical analysis and finite element analysis are rare.Therefore,this paper first describes the working process of this kind of joint under seismic load by using the method of theoretical analysis.Mechanical analysis method is used to predict the M-θ curve of the joint under earthquake load,and the free rotation stage,elastic state stage and plastic state stage of the M-θ curve are described by theoretical formula.In addition,working with gaps should be the normal state of work under the seismic load of the side span half-tenon joints in Chinese ancient wooden buildings.However,few scholars have studied the working state of the side span half-tenon joints with gaps under the seismic loads,so this paper uses finite element analysis to study the mechanism of the above-mentioned joints.From the results of finite element analysis,it can be known that the existence of gaps will affect the stress state of the joint under seismic load.Under the reciprocating action of the seismic load,this type of joint has a large slip,which makes the "shuttle-shaped" hysteretic curve become "inverse Z-shaped".The existence of gaps also led to the decline of the ultimate seismic bearing capacity,and the stiffness degradation law and displacement ductility index also changed.