Study On The Seismic Performance And Numerical Simulation Methods Of Ancient Beam-lifted Timber Structure

The existing ancient timber structure carries Chinese cultural history derivesfrom five thousand years, whose value is immeasurable. Old wooden buildingssuffered serious damages in both Wenchuan great earthquake and Lushan Ms7.0earthquake, in Sichuan Province. For this reason, it is imperative to study theseismic behavior and numerical simulation method of ancient timber structure.Focusing on this demand, the paper completes the following four missions:(1) On the basis of widely collecting and thoroughly understanding theknowledge about ancient wooden buildings, including the architecture form, stylecharacteristic, structural arrangement, bearing mechanism, constructionalmeasures and so on, plenty of experiments about mechanical property of timberused in the model are conducted, obtaining the tensile strength, compressivestrength, elastic modulus and Poisson ratio. Then we combine the fieldinvestigation and measure results of Pavilion of the Rain in the Imperial Palaceand consider various factors contributing to anti-seismic capacity as a whole,including the effect of structural members such as column foundation,mortise-tenon and joints, sparrow brace, and also the effect of non-structuralelements, for instance, doors, windows, infilled walls and so on. We simplify thetest model and complete the processing production of1:6scale model of Pavilionof the Rain.(2) Based on its unique style, the author chooses proper similarity criterionand conduct the shaking table tests of the model, according to the fundamentalassumption of equivalent linearization. The experimental results show that, themortise-tenon joints of wooden structure have much stronger energy-dissipatingcapacity and can reduce structural dynamic response effectively. Seismic actionproduces severe structural deformation, leading to the damage of non-structuralelements such as doors, windows and so on. Consequently, appropriate measuresshould be taken as required immediately to these non-structural elements inactual structure. The paper synthesizes the test phenomenon and data to analyzethe structure, a variety of seismic performance indicators of the model areacquired, including the dynamic response of each floor, free vibration frequencies,damping properties of the whole structure and so on. Besides, it transfers theresponse of the model to that of the prototype by the law of similarity principle.(3) The paper has accomplished the numerical modeling of the test model bythe use of the finite element software ANSYS. According to the relevant researchresults about the structural characteristics and construction measures of ancientbuildings, proper assumptions are taken during the modeling, including that: thebeams and columns are still in elastic state during earthquake; only the memberof doorframe is considered in the doors and windows; the mortise-tenon joints of the whole structure have the same rigidity, regardless of whisker pullout,etc. An analysis method is proposed which considers the mortise-tenon joints tononlinear torsional spring and takes the effect of non-structural elements intoconsideration. Then finish the structural numerical modeling.(4)The paper determines the parameters of nonlinear semi-rigid nodes,according to the model analysis results of finite element model and the measuredfrequency of actual structure, and compares the nonlinear time-history analysisresults with the measured data. It not only verifies the rationality of the analysisresults in this article, but also provides reference for numerical simulation ofsimilar structure.