Seismic Behavior Experimental Study On Mortise-tenon Joints Of Column And Tie Timber Construction2

Timber structure is the main structural style of ancient buildings in China,wooden beam framework and column and tie timber construction are the most widly used types. Column and tie timber construction has been applied to many existing buildings in Sichuan, Chongqing, Yunnan, Guizhou regions and some new publlic buildings in tourist attractions. It is favored because of light weight, flexibility of arrangement and large space. Column and tie timber construction shows better seismic performance for over sloping instead of collapse under earthquake, which protects people's lives and properties. In the theories, there is no stipulation about design,acceptance, performance evaluation and strengthening of column and tie timber construction in the code of timber structures. And in the actual engineering aspect, the new column and tie timber construction are builded according to the traditional process,while it is a potential security liability for ambiguity seismic mechanism.Most Chinese ancient timber buildings are connected by mortise-tenon joints. At the joints of column and tie timber construction, sereval columns were composited by one beam which's section wasn't weakened, therefore the structure is good in integrity.Studies have shown that joints are the control link of behavior of traditional wooden structure. In order to clarify the seismic mechanism of column and tie timber construction, joints need to be study.By completing the monotonic static loading test and low-cyclic reversed loading test on side straight mortise-tenon joints and middle joints of column and tie timber construction, the main conclusions were as follows:First, the moment-rotation hysteretic curves are Z-shaped form, and have a long segment shift plan.Second, the moment-rotation skeleton curves show that the joints go through slip phase and up phase. The slip stage stiffness is small, in up phase, the stiffness suddenly increased, and then degenerate gradually. When the angle reaches about 0.11 rad, the stiffness comes to the minimum value.Third, the joints show some strength degradation law under low-cyclic reversed load, which mainly in the second cycle under the same control displacement. The magnitude of the degradation is only a little.Fourth, by caculating the equivelant viscous damping coefficient of side joints andmiddle joints, the results show that they have similarenergy dissipation capacity.Fifth, the deformation of joints increase with increasing moment, there are no obvious yield stage.Sixth, theoretical models of joints under positive load and uninstall and reverse load and uninstall were derivated, and the theoretical and experimental curves are in good agreement.Seventh, the influence to theoretical models of joints of the initial gap was discussed. The research indicates that the larger the initial gap, the longer the slip segments, the larger the initial stiffness in effective angle phase, and the slower rate of degradation of stiffness.By theory research and experimental studies on the mortise-tenon joints of Column and tie timber construction, the seismic mechanism of the joint was found. And that also provides theoretical base for construction of engineering, maintenance and reinforcement of timber buildings.There are three innovative points about the research: exploratory research on static behavior and seismic performance of side straight mortise-tenon joint of column and tie timber construction, exploratory research on static behavior and seismic performance of middle straight mortise-tenon joint of column and tie timber construction, built up the theoretical model of.the mortise-tenon joint of column and tie timber construction.