| Fawang pagoda in Xianyou Temple(A.D.601) is located in Heihe yukou Zhouzhi County of Shaanxi,it Is our country only Sui dense-yen existing pagoda With important scientific,historical and artistic value.It have elapsed since the 1400 years of history,experienced a number of earthquake disaster while it had remained intact, reflecting nicer seismic performance.In this paper,the geometry and the structure had been studied in accordance with the measured data of relocation of Fawang pagoda, the finite element analysis model is built by ANSYS software,And its dynamic characteristics are analyzed,discussed the seismic performance of Fawang pagoda, designed for providing a theoretical basis and technical reference designed to repair, reinforcement and protection of China's ancient masonry.The main conclusions is as follow:1,Introduced the structural characteristics of ancient masonry,and analyzed the destruction factors of ancient masonry.2,Introduced the seismic performance research of Masonry pagodas at the present stage,summed up analytical method on the seismic performance of Masonry pagodas.3,Analyzed the structure type and the tower damage situation of Fawang pagoda, it is square in plane and seven floors comprised of the base,tower body,tower yen and tower top.The tower body showed "tube" structure.4,Using the large-scale finite element software ANSYS built the three-dimensional finite element model of Fawang pagoda,the model for modal analysis,form which the two dynamic properties that the natural cycles and the natural frequency is get.The influence of the mesh,the base,the mortar strength and the door opening on the dynamic properties is discussed,only to obtain that the influence of the mesh and the base is relatively small,that can be neglect,but the mortar strength had a great influence on the dynamic properties,so it is need to be though in the maintenance and repair of the tower in the later.5,The natural frequencies derived from the empirical formula is compared with the one derived from the finite element model,it showed that the two have little difference, which is in line with norms,so the finite element model in this article is very credible.6,According to the rules of symmetry,quality and stiffness changes in uniform layers of Fawang pagoda,the structure will be simplified into a model structure of the cantilever bar with variable cross-section then compared the natural frequencies derived from the model in front of simplify and the one derived from simplified model and found that the two have little difference in the framework of norms,and thus has come to the simplified model is in line with the requirements.7,Three types of seismic waves are selected according to Fawang pagoda sites, adjust the seismic waves according the type about the seismic fortification intensity of the site where the Fawang pagoda,import the after adjusting seismic wave by not too strong and strong earthquakes.And then the simplified model of Fawang pagoda's displacement time-history response is analyzed.Found that the drift angle start amplification from the sixth,it is explain that the towers start more easily damaged from the sixth storey;the Stress analysis cloud figure shows that the stress mainly concentrated on the contact surface of tower body and the base,so the base wall is serious damaged,it provides the theoretical data for the reinforcement and repair of Fawang pagoda in after,at the same time it provides a kind of thought to the similar masonry pagodas' analysis. |
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