Research On The Offsetting Correction Scheme And Structural Performance Of Ying-Xian Timber Pagoda

Yingxian Wooden Pogoda is the highest existing ancient timber frame building in the world, and it’s the only pure wooden structure tower, as the first batch of national key cultural relics protection units.Yingxian Timber Pagoda built in AD 1056 is a tower of octagonal pavilion-style and connected by the nonrigid mortise connection mode. The pagoda uses more than 400 forms of Dou-Gong, which has been the most distinctive part of the tower. As the last millennium load bearing, earthquake damage, material aging, artificial damage and so on, the pagoda especially the second layer is seriously distorted and damaged. As time flies, the tendence of tilt and twist deformation, cracks and damage deterioration is worsening, therefore, the wooden pagoda is of urgent need to repair and reinforcement.This research under the frame of major project "Condition evaluation, safety margins and property retention of the timber structure of ancient buildings" (51338001) of Nature Science Foundation in China, designed the layout plan of reset force systems based on the 3 reset schemes of stretch-draw horizontally, the internal "Shore-Tension" and Jack up-Tension which were proposed by the research group of conservation of historic building in Yangzhou University. And the method of finite element numerical simulation is used to study on the structural properties of Yingxian Timber Pagoda which is under the action of reset force systems. This thesis had finished following research work:(1)The analysis and evaluation of damage characteristics and repairing schemes of Yingxian Timber Pagoda. Based on literature materials and on-site investigation report, this paper made a systematic analysis of damage conditions of the pagoda and summarized the historical repairing projects as well as the existing maintenance schemes of reinforcement. In addition, the characteristics of different repairing schemes were evaluated by reference to the principles of protection of cultural relics in this paper.(2)The establishment of finite element model of Yingxian Timber Pagoda based on damage to status quo and deformation mechanism. According to the research data of current damages to Yingxian Timber Pagoda, the finite element modeling methods, such as adjusting the effective area of beam and column and the stiffiness of bracket sets sectionally which can reflect damage status of components, is put forward. And based on the commercial software ANS YS, the finite beam element model which can reflect deformation and damage characteristics of the pagoda is established to be made as the basic model of simulation analysis.(3)The simulation analysis of structural properties of Yingxian Timber Pagoda which is under the action of reset force systems. Prof. Based on the basic thoughts of 3 restoration schemes such as stretch-draw horizontally reset, the internal "shore-tension" reset and jack-up-tension reset, contraposing the damage and deformation characteristics of Yingxian Timber Pagoda, the specific layout plan of reset force systems was designed in this paper. Besides, based on the platform ANSYS, the reset state of each follr and the maximum stress of components under the action of different reset force systems were analyzed by computer simulation.(4)The structure performance evaluation of Yingxian Timber Pagoda under restoration system. To target the effective restoration of the integral structure, the minimum stress increment of components and the maximum stress less than the admissible value, the restoration results and stress state under the action of reset force systems were compared. And consider of the process factors such as workyard and mechanical equipment conditions, some comprehensive evaluations and some suggestions for further research to the three restoration methods were put forward.The simulation analysis results of the 3 restoration schemes of Yingxian Timber Pagoda in this paper can provide theoretical basis for the repairation and reinforcement of the pagoda in the future. And the relevant restoration methods can provide beneficial references for repairation and reinforcement engineering of ancient timber frame buildings of our country.