Mechanical Property Analysis On Mortise-Tenon Joints And Its Finenumerical Simulation In Ancient Chinese Timber Structures

Ancient Chinese timber structures is an independent system in the world architecture system, it has been developed for nearly seven thousand years since it was produced、evolved and expanded. These outstanding architectural features is to wood truss bearing (wall do not bear the weight of, only to the disjunctive space and building insulation effect), between components by mortise and tenon connection. Because of the mortise tenon joint with excellent energy dissipation performance, hence the ancient Chinese ancient wooden buildings monomer, compared with other system of ancient architecture has better seismic performance. However, the complex properties of wood material and node of the load transfer mechanism is not clear, so from the material, experimental study and numerical simulation of angle inquiry its impact on the ancient wooden structure building seismic performance is very necessary!The main research work of this thesis is as follows-Took the Embrasured Watchtower of Yong Ning Gate of Xi’an City Wall as research object, aaccording to the Kung-ch’eng tso-fa tse-li of Qing Dynasty, produced the three specimens of the scaled ratio is 1:6 straight mortise tenon joints of wooden frame model by horizontal low cyclic loading test and the hysteretic characteristics of straight tenon joint force mechanism analysis, study on the failure characteristics and the lag of timber frame performance, reveals the destruction of ancient Chinese timber buildings, mainly because of hysteretic characteristics of tenon and mortise mutual extruding and produce severe plastic deformation that tenon pulled out, and then the whole structure function is lost; based on the moment rotation joints model of pseudo static test in reciprocating horizontal load under the action of hysteretic curves and skeleton curves, and also based on the similarity relationship between the experimental model and the original structure, the bending bearing capacity and rigidity of the prototype of the prototype are derived, and the influence of the structure on the seismic behavior of the whole structure is also tested.In view of the existing literature on the assessment of wood strength criterion is insufficient, it summarizes the commonly used criteria of wood strength, with 439 samples of spruce biaxial tests at different loading ratio and different grain angle, from the point of view of statistical analysis, using Matlab mathematical software programming calculation, prediction the ability of the eccentric shaft and biaxial strength of the 11 kinds of strength criterion used in wood are evaluated objectively. The results show that the applicability and practicability of the comprehensive consideration of strength criterion are considered, the Tsai-Wu criteria for the stress interaction coefficient F12=0 are the best.Through further research on the physical and mechanical properties and strength criterion of wood, consider the wood along the longitudinal and transversal directions with different intensity, and the same direction of tension, pressure degree is not the same characteristics; According to the results of this paper, the yield characteristics of wood in three dimensional stress space are described by using Tsai-Wu criterion; Based on ABAQUS/Explicit finite element software platform, using Fortran language to the user material subroutine (VUMAT) interface for the secondary development, the orthogonal anisotropic elastic and plastic constitutive model is established, provide factual basis for implementation of mortise and tenon joint of wooden frame of 3D model refinement analysis.Access to two times the development of prepared wood orthotropic elasto-plastic constitutive subroutine in ABAQUS/Explicit platform (VUMAT), a mortise and tenon joint of wooden frame of 3D model of friction contact characteristics between the tenon and the mouth of the prime consideration, analysis of its mechanical properties under quasi-static cyclic loading, moment rotation angle hysteresis curves and skeleton curves were obtained, and combined with the experimental results of this research group, the numerical model is validated and analyzed, The feasibility of the numerical model is proved.