Simulation Study On Mechanical Properties Of Dovetail Joint In Timber Construction

This paper takes dovetail joints widely used in ancient buildings as the research object,and designs two second-grade material dovetail joints and one third-grade material dovetail joint in different model proportions according to the "Building Method" "wood system" as the standard In this study,the hysteresis curve,skeleton curve,stiffness and strength degradation curve,energy dissipation capacity and joint tenon stress change rule of the node were obtained.The effects of different model scales and equivalent material grades on the mechanical properties of dovetail joints are analyzed,and recommendations are given for the selection of the scale ratio of dovetail joints.The main conclusions are as follows:(1)The hysteresis curve of the node is generally "Z" type,with obvious "pinch-up effect" and slip,indicating that the node has shear deformation and slip during loading,and the amount of slip increases with the increase of the rotation angle.M(bending moment)during reverse loading is less than forward loading,the peak bending moment YS-2>YS-1>YS-3,YS-1>YS-4,indicating that the higher the grade,the greater the bending moment of the node;The slopes of the forward and reverse curves of the nodes near the origin are higher,because the column rotation needs to overcome the additional bending moment of the axial force;the growth rate of the bending moment of YS-1 is significantly faster than that of YS-4,and the bending moment of YS-1 at the same rotation angle Bigger.(2)The initial stiffness of the node is large,and the forward and reverse stiffness gradually decreases with the increase of the rotation angle.The stiffness degradation rate of YS-1,YS-2 and YS-4 is faster before 0.015rad,and the stiffness degradation of YS-1 and YS-4 after 0.015rad The speed slowed down gradually to a horizontal state.The stiffness degradation of YS-2 is the most obvious in the whole loading process,and the degradation rate of the overall stiffness of YS-3 is the slowest.The initial stiffness of forward loading YS-2 is 594KN.m.rad-1,which is 3.4 times and 9.4 times that of YS-1 and YS-3.The reverse loading law is similar to gradually decreasing with the increase of the model proportion.The initial stiffness of YS-1 forward and reverse loading is 1.3 times and 1.4 times that of YS-4.(3)The intensity degradation coefficient YS-2(0.98)>YS-1(0.97)>YS-3(0.95),gradually decreases with the increase of the scale of the model.Comparing YS-1(0.97)>YS-4(0.96),it is found that the strength degradation of the second-class material nodes is greater than that of the third-type material nodes at the same model scale.(4)YS-3 has an initial he of 0.14 and 0.22 at 0.08rad,which is significantly stronger than YS-1 and YS-2,It shows that the larger the model ratio,the stronger the energy consumption ability.When YS-4 is 0.08 rad,he is 0.17,which is lower than the energy value of YS-1 node at this corner,It shows that the energy dissipation ability of the second-class material node is stronger than that of the third-class material node at the same model scale.(5)The amount of tenon under the first-level control displacement of YS-1,YS-2 and YS-4 is about 1.76mm,and the amount of tenon under YS-3 is significantly smaller at 0.66mm.YS-1,YS-2,YS-3 and YS-4,the maximum tenon pulling amount under the last level of control displacement is 13.5mm,17.8mm,4.9mm and 11mm respectively,indicating that the larger the model ratio,the smaller the tenon pulling amount,and At the same model scale,the amount of tenon joints of the second-class wood joints is larger than that of the third-class wood joints.