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Yingxian Wood Pagoda, built in 1056, is located in the town of Yingxian County, Shanxi Province, China. It is the oldest and highest standing ancient wood structure in China. The pagoda is octagon-shaped in plan, with a total height of 67.31m and a base diameter of 30.27m. It appears as a five-storeyed structure, but actually consists of nine storeys, with four shorter but stiffer storeys hidden between the five apparent storeys. Yingxian Wood Pagoda was built without any metal connectors like nail, screw, or bolt. Instead, Tenon-Mortise connections and Dou-Gong brackets were used to connect all posts and beams. Tenon-Mortise connections and Dou-Gong brackets have been playing a vital role for the pagoda to resist severe winds, earthquakes and some human-induced disasters for nearly a thousand years. To evaluate the safety of the pagoda, it is, therefore, useful to investigate the structural performance of the beam-column joints, most important for Yingxian Wood Pagoda to resist lateral load. In this study, two models of typical beam-column joints of the pagoda, MBCJ-I and MBCJ-II, were manufactured following a ratio of 3.4 to the prototype of the joints. Non-destructive cyclic loading test of the models under different vertical load and destructive cyclic test of the models under vertical load of 20kN were conducted. The hysteretic stiffness of MBCJ-I was lager than MBCJ-II, and increased linearly with vertical load N. The relationship between and N was obtained by regression of the test results using the least square method. The stiffness of model joint under vertical load was 70.6kN/mm. The failure modes, energy-dissipation performance, moment resistance and bending stiffness of both model joints were derived and discussed.

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Wooden buildings which has a long history, is one of the earliest forms of building structures by mankind.The structure form and construction method of are different from the common prestressed structure,therefore,the prestressing loss caused by the external prestressed structures is different from that of the common prestressed structure.It is an effective method to reduce the large deflection of large-span wooden structure by external prestress method.Through the real model test of the external prestress tension at scale of 1:2,and after long-term observing on parabolic wooden beam of external prestress with initial pretension force,we can quantitatively analyse the effections of prestressing loss of prestressed rebar due to the creep of wood.At the same time,this paper gives the deflection calculation formula during the term of test.The conclusion obtained is useful to designers.

People have widely uesd long- history wooden buildings in the ancient and mordern architecture.But the modulus of elasticity of the wood is smaller as well as the fact that the stiffness of wood is lower. In order to solve the problem of deficiency of the stiffness of large-span wooden beam from the practical engineering, this paper presents the method of external prestressed wooden beam, and the calculation method of deflection of wooden beam through model test of 1:2 scale. In addition to it, the paper also analyzes the factors which affect stiffness of wooden beam. The result shows that stiffness of this kind of wooden beam is greatly improved compared with the common wooden beam in the same cross section. Steel has a predominant tensile characteristics, it is an effective method to reduce undue deflection of large-span wooden beam by external prestress method. This construction techniques has greatly applicational value in the reinforcement and strengthening ancient buildings and modern design and construction of large-span timber structure buildings and bridges.