Experimental Research On Mechanical Property Of Mortise-Tenon Joint Of Chinese Ancient Timber Buildings

Chinese ancient timber buildings with high historical, artistic and scientific value are not only the valuable cultural heritage of the Chinese nation but also an important part in the history of world architecture. Every member in Chinese ancient timber buildings is combined with each other by mortise-tenon connection. The tenon is cut from timber beam while the mortise is drilled from timber column and compared with the original cross section the material of the mortise-tenon joint is impaired. The mortise-tenon joint becomes the weakened part of the whole structure and its performance has a crucial effect on the whole structure. So it is of important significance to research the performance of mortise-tenon joint for the safety assessment and repair protection of Chinese ancient timber buildings.Based on the National Science-technology Support Plan Project:planning and integrated lifting technology demonstration of traditional ancient settlements (2012BAJ14B05) and research status at home and abroad, experimental study of straight mortise-tenon joint and timber frame connected by straight mortise-tenon widely used in the Chuan Dou-style timber frame building is conducted. In this paper the specific work is summarized as follows:(1)The research background and significance of Chinese ancient timber buildings are briefly introduced, its research status is systematically summed up, and then the main research contents of this thesis are summarized.(2)The structural forms, construction features, the origin, development and classification of mortise-tenon connection are introduced. The related mechanical properties of timber and the main factors affecting the strength of timber are summarized. Timber material test of fir which is in the corresponding period with the the test components’ fir is conducted to obtain various mechanical indices.(3)The low-cyclic reversed loading test of six straight mortise-tenon joints is conducted whose experiment parameters are wood peg and sectional dimension of tenon. The failure mode and mechanical performance are studied and the influence of wood peg and tenon sectional dimension to bearing capacity, stiffness and energy dissipation capacity of straight mortise-tenon joint is discussed. The experiment research shows that wood peg can effectively prevent tenon pull out from mortise; ruling out the influence factors of specimen initial crack and obvious timber discreteness, increasing the cross-sectional size of tenon can effectively improve the bearing capacity of joint and reduce the energy dissipation capacity at the same time.(4)A Chuan Dou-style timber frame using straight mortise-tenon joint as the factual beam-column joint is designed and the low-cyclic reversed loading test of the timber frame is conducted. The hysteretic curve, skeleton curve, strength and stiffness degradation curve and energy dissipation capacity of the timber frame under low reversed cyclic load are analyzed.