Experimental Study And Theoretical Analysis Of Traditional Timber Typical Mortise-tenon Joints Based On The Wood Friction Mechanism And Embedded Pressure Characteristics

With social and economic development,people's cognition of traditional timber frame aseismatic system is getting deeper and deeper.The timber structure of Chinese ancient buildings and traditional folk dwellings are rich and unique in seismic intelligence.It has also aroused the interest of experts and scholars in the research of traditional wood structure in China.This paper is intended to be based on previous research.Of the traditional timber building typical mortise and tenon joints:steps through motise-tenon joints,fang under steps through motise-tenon joints,half mortise-tenon joints and dovetail joints model based on wood's friction mechanism and the characteristics of the pressure test,numerical simulation and theoretical research.Under different friction coefficient,the tenon nodes were selected for low-cycle reversed loading test.The influence of friction on seismic performance of the joints are quantitative studied.In this paper,the seismic performance of the tenon joints under different side gap conditions was studied by low-cycle reversed loading test.The finite element ABAQUS analysis software was used to analyze model of low-cycle reversed loading test.The theoretical analysis and derivation based on the wood friction mechanism and the embedded pressure characteristics are carried out on the typical tenon joint of traditional wooden structure.In this paper,the experiment of the shaking table of two layers of wooden structure model is carried out.At the same time,a fan-shaped viscoelastic dampers were installed on the tenon joint of the building structure model,and the shaking table tests were carried out for the enhanced integral building model of the installation dampers.Comparison of experimental results of two architectural models of shaking table tests.This paper mainly completes the work:(1)Chapter 2,by mortise tenon joints with oil processing and without oil processing in two ways,control the friction coefficient of traditional wood mortise and tenon joints model of typical full scale low-cyclic reversed loading tests,study mechanics and energy dissipation characteristics of mortise-tenon nodes in different friction coefficient.Got conclusions as following:The friction has little effect on the failure shape,bearing capacity and ductility of the mortise tenon joints.The relationship between the friction coefficient change and the size of the hysteresis loop area is affected:half motise-tenon joints>fang under steps through motise-tenon joints>steps through motise-tenon joints>dovetail motise-tenon joints;The change of the friction coefficient of the steps through motise-tenon joints,fang under steps through motise-tenon joints and half mortise-tenon joints model has great influence on the initial stiffness,and did not cause obvious regular change of dovetail joints model;The equivalent viscous damping coefficient of steps through motise-tenon joints of the friction coefficient 0.38,which is more than twice that of the friction coefficient 0.20.The equivalent viscous damping coefficient of fang under steps through motise-tenon joints of the friction coefficient 0.38 is 1.4 times the friction coefficient of 0.20.The effect of friction on the equivalent viscous damping coefficient of the dovetail joint is mainly reflected in the speed of the node energy consumption.(2)Chapter 3,through controlling constant width mortise,and different width tenon of nodes,making the steps through motise-tenon joint,half mortise-tenon joint and dovetail three kinds of nodes,each node was divided into three models of tight,medium and easing,a total of nine models,research on the close degree between every mouth side effects on the seismic performance of mortise and tenon joints by low-cyclic reversed loading tests.At the same time,through the use of the simple moire technique(5mm x 5mm grid),the phenomenon and the process of the insertion of the tenon during the test are observed.The results show:The close degree has great influence on node energy consumption,ultimate bearing capacity,initial stiffness and ductility,and the closer the tenon,the more obvious the brittle character;Ultimate bearing capacity relation:Tight node model>Moderate node model>Easy node model;Initial stiffness size relationship:Tight node model>Moderate node model>Easy node model;Equivalent viscous damping coefficient size relationship:Moderate node model>Tight node model>Easy node model;Tight node model ductility is bad,easy ductility is good.(3)Chapter 4,using the large finite element software ABAQUS to simulate the low-cycle reversed loading test of the steps through motise-tenon,the semi-tenon and the dovetail motise-tenon.The results of finite element simulation are consistent with the test results,and the accuracy of this method is verified;Joint lateral gap of mortise-tenon joint hysteretic energy dissipation effect is more apparent,but little effect on the performance of mortise-tenon joint bending,showed motise-tenons lateral friction between their motise and tenong is very important to hysteretic energy dissipation effect.(4)Chapter 5,set up M-? relationship formula of motise-tenon joint based on friction mechanism and entrapment of-wood properties,and according to the theoretical formula calculation made the M-?relation curve,comparison and analysis test skeleton curve,for the traditional timber joint design and maintenance of testing provides a theoretical reference.(5)Chapter 6,the design and manufacture of a two-layer timber frame building model,The two-way shaking table test of the model was carried out.Quantitative study of the model structural characteristics and dynamic response.A fan-shaped viscoelastic dampers were installed in motise-tenon joints of the model,and the shaking table test of the two architectural models is compared and analyzed.The results show that structure model has a good recovery deformation,mortise-tenon joints equipped with viscoelastic dampers,enhanced to provide plenty of restoring force structure,and protect the mortise-tenon joints from pull out,to ensure the good energy dissipation mechanism of mortise-tenon joints.