Research On The Behavior Of Mortise-tenon Joints Of Ancient Timber

The ancient construction is an important part of Chinese history and culture, which is contained of the wisdom of ancient Chinese outstanding skillful craftsmen, so it has the very high historical and cultural value. The connection mode of mortise and tenon joint is one of the outstanding performances of craftsman’s wisdom. Without a nail or an iron, it still has very good connection effect, moreover, it also shows the superior characteristics on the force transmission way and the seismic performance. Therefore, it is popular among the ancient craftsmen. Because the mortise and tenon joint in the process of structural force bearing is in a key position, needing the effective connection with adjacent components and it is weakened compared with other parts, the mortise and tenon joint is more possible to be made large deformation and damage, even to failure. Therefore, study on the characteristics of mortise and tenon joint is of great importance for ancient timber structures. In order to solve the seismic problem of mortise and tenon joint in timber frame, for seismic performance of typical mortise and tenon joint in the earthquake, ZhouFuJiu house in Yangzhou is as the prototype. The main connection forms of typical mortise and tenon joint are summarized, and its theoretical mechanics performance of mechanical characteristics and damage forms is analyzed, and the various typical mortise and tenon joints are carried on under low reversed cyclic test and finite element simulation analysis. So seismic performance index of the typical mortise and tenon joints under the low reversed cyclic loading are obtained, and various seismic performance of different typical mortise and tenon joints are compared, and different stages of the bending moment-corner formula can be obtained. So the detailed research contents are as follows.(1) Based on characteristics of Hui style, its unique regional style, timber frame characteristics and the typical connection forms of mortise and tenon joint are summarized.(2) Before performing the test of mortise-tenon joint, new wood was determined to analyze physical and mechanical performance indicators by material performance testing, and got some values of wooden strength, such as compressive strength parallel to grain, compressive strength perpendicular to grain, etc..(3) By choosing two typical types of mortise and tenon joint to analyze its mechanical properties, mechanical characteristics and failure modes were analyzed in the process of loading.(4) Based on the various wooden physical and mechanical parameters, nonlinear finite element simulation analysis was carried out on the several typical mortise and tenon joint nodes, and analyze the stress of the analysis model under low reversed cyclic loading, obtaining parameters such as stress, the internal forces in the process of loading.(5) The experiments on wooden mortise-tenon joint were carried out in the school laboratory, and the seismic performance indicators could be obtained on the new wood, such as the M-θ hysteresis curves, skeleton curves, etc. What is more, the seismic performance of various typical wooden mortise-tenon joints were compared and analyzed.(6) Comparing the results of finite element simulation with experiment, the different forms of angle stiffness formula was concluded according to the test of the skeleton curve of mortise and tenon joint.This paper carried on the beneficial exploration on ancient wooden mortise and tenon joint in Hui State area under the seismic action, especially on the study of the structure made by old wood, it can truly show the mechanical performance of mortise and tenon joint in the old building. However, due to the limitations of the testing conditions and finite element analysis software, the expression on the superficial damage of mortise-tenon joint and the corresponding reduction factors need further research.