Mechanical Behavior Of Mortise And Tenon Joint Nodes In Reticulated Timber Shells

Nowadays the greenhouse effect is severe and the concept of green building has become an industry’s common understanding,the development of timber frame construction has entered a new phase.The design of the nodes is important,as they will affect the force performance of the entire timber shell structure.The design of the nodes is of paramount importance,as they will affect the load-bearing performance of the whole timber shell structure.In this study,we have proposed a node for connecting timber elements by means of mortise and tenon,which avoids the direct intervention of bolts and reduces the negative impact of bolts on the elements.The research on this type of connection nodes is not comprehensive,so it is necessary to analyze its force performance.The main research elements of this paper are as follows:(1)After analysing the force performance of the combined structure and the mortise and tenon structure,it is determined that the node connection method in this study is that the lateral corrugated web of the steel hub is embedded in the timber member to form a mortise and tenon connection,and the theoretical formula for calculating the bending load capacity of the node is proposed according to the force situation of the node under the action of bending moment.(2)The load-displacement curve and moment-angle curve of the mortise and tenon joint node are obtained through finite element simulation.As can be seen from the stress cloud diagram,the compression zone produces higher stresses when the timber member is extruded against the corrugated web,followed by higher stresses in the tension zone when the corrugated web restricts the deformation of the timber member,and as the load increases,the corrugated web in the tension zone yields,leading to the failure of the node after the flange plate yields.The node is designed with flat grooves to avoid the cross-grain diagonal stresses caused by the pin grooves and to improve the strength,stiffness and stability of the node.Based on the finite element analysis results,the correctness of the calculation formula for the load bearing capacity of the mortise and tenon joint node is verified.This paper also presents a seismic analysis of the node,which shows that the hysteresis curve of the node is bowed,with a certain degree of pinching in the middle of the curve,which is mainly due to the slippage of the timber member and the corrugated web under load,and the overall seismic performance of the mortise and tenon joint node is relatively good.(3)This paper establishes a parametric model of the mortise and tenon joint node and discusses the effects of different bolt strengths,flange plate thickness,corrugated web thickness,corrugated web height and axial pressure on the force performance of the mortise and tenon joint node.The parametric analysis shows that the flexural load capacity of the node increases with the thickness of the flange plate and the thickness of the corrugated web,the node stiffness increases with the thickness of the web,and the height of the corrugated web and the strength of the bolts have less influence on the force performance of the node.The application of axial pressure results in a significant increase in the load capacity and stiffness of the node,but as the pressure continues to increase,the increase in both mechanical properties decreases until they remain constant.The nodes are subject to instability damage when the thickness of the corrugated web is too small,and brittle damage when the thickness is too large and the mechanical properties of the timber member itself are reduced.Finally,this paper proposes a reinforcement method to optimise the mortise and tenon joint nodes,which can effectively improve the strength,stiffness and plastic deformation capacity of the nodes.