Research On Joint Aseismatic Performance Of The Structural Carpentry In The Qing Dynasty

Ancient Chinese timber Structures is the representative of the Oriental ancientbuildings, and has a style of its own on the world ancient architecture system,it hasimportant historical value and directive function on analysis and study of the structure’sseismic performance.Took the Embrasured Watchtower of South Gate(Yong Ning Gate)of Xi’an City Wall as research object, employed the research methods of theoreticalanalysis and experimental study,the energy dissipation characteristics between thecolumn and headstone of ancient buildings’ timber frame under the action of theearthquake were studied;the load-transferring mechanism, Damping properties as wellas energy dissipation capability of mortise and tenon joint between beam and column(including Que-Ti) were analyzed in this paper.Through the analysis of timber property and the study on the load-transferringmechanism and failure mechanism of half-mortise and tenon joint,the conclusion whichjoint failure is the main effect factor of structural failure and accumulated plasticdeformability give rise to joint failure can be obtained.Though The pseudo-static experimental study on Alone column model，we canconclude that, under seismic action, the column’s Plastic deformation and energydissipation is very small,its equivalent viscous damping coefficient changed from0.04~0.08, which was affected by the axial force.So it can be looked as an elasticcomponent for the structural seismic performance analysis.Applying mechanics theoretical knowledge,computational formula about flexuraland shear bearing capacity of Que-Ti,half-mortise and tenon joint with Que-Ti wasobtained, simplified finite element model of column-beam joint which took Que-Ti ’seffect into account also was got. Took the Embrasured Watchtower of Yong Ning Gate(South Gate) of Xi’an CityWall as research object, according to the rules of Gong Cheng Zuo Fa Ze Li of QingDynasty,the low cyclic lateral loading tests were conducted on two groups timber framemodels,one group hasn’t Que-Ti,the other one has it.Two kinds of timber frame joints’characteristics of stressed deformation and working mechanism were analyzed. themoment-rotation hysteresis curve,moment-rotation skeleton curve, characteristicparameters, stiffness degradation rule,restoring force model and damage expression ofmortise-tenon joints were obtained. Experimental results proved that Mortise-tenonjoint has a good ability of rotation,then Que-Ti can effectively improve the joint’sstiffness,to improve the integrity of the structure when bearing the lateral force.The column frame and mortise-tenon joints’ energy consumption ability werevaluated. It is determined that until the frame destructed,every timber frame modeldissipated about2000kN·mm energy averagely.while the energy of every joints’transformation dissipated just about1/10of it.The mathematical model between Thedissipated energy of mortise-tenon joint’s transformation and displacement’s ductilityfactor was fitted.Applying related mechanics theoretical knowledge,under three assumingcondition(rigid column-beam connection， semi-rigid joint and semi-rigid jointthinking about second-order effect),the change rule of the Timber frame internal forceand displacement was calculated,though combined with test results,the calculationmethod of Timber frame internal force and displacement was obtained.