Research On Shear Properties Of Dry Joint In Segmental Precast Concrete Bridges With External Tendons

Precast segmental construction technology with external tendons accord closely with the development of prestressing technique and modern construction technology, factory production and mechanization of construction can be realized. The thchnology has been widely accepted by the counterpart and utilized more and more in the practical bridge engineering all over the world. Joint is the one of the key structures in precast segmental construction bridge with external tendons, But lack the system to study deeply at home and abroad. According to the research of "Study on New Technology of Precast Segmental Construction with External Tendons", the shear properties of dry joints key-tooth are analyzed for both experimental and numerical simulation, the main research work and results are as follows:(1) The development and research on segmental precast concrete bridges with external tendons and its structure of joints are introduced detailedly at home and abroad, main problems of researches at this stage are pointed out.(2) The main types of joints and characteristics and application scope of various joint types in segmental precast concrete bridges are introduced detailedly. The computational formula about joints shear capacity in segmental precast at domestic standards, American Specification AASHTO and have been proposed by other scholars are compared and analysed. Then the factors affect of shear capacity is analysed.(3)12twin pairs of dry joint single bond model were made and8of them are tested. Then six groups valid data are compared and analysed respectively. The results of the analysis of strain data between male teeth and female teeth showed that there is the same position of maximum strain point in male teeth and female teeth no matter how much horizontal pressure had been exert. Law of the strain of maximum strain point is represented in the vertical load.(4) According to the analysis of the relative slipping data between male teeth and female teeth, load-slip curves has been drawn respectively in three levels of horizontal pressure, which were1MPa,1.5MPa,2MPa, The curve is composed of upward section that slope goes down with the load increase and downward section.(5) According to the occurrence and development of cracks of test components, the occurrence regularity of cracks were almost the same in three levels of horizontal pressure, which were1MPa,1.5MPa,2MPa, it is manifest that the subject side in male teeth and female teeth and the part of key-tooth in male teeth, and the location and strike of cracks were almost the same. while the bottom of the female teeth of components shows compression failure when confront with the occlusion of key-tooth and female teeth.(6) The finite element analytical model was established for male teeth of test components. nephogram of displacement and stress under different load case of male teeth was obtained and the curve between load and stress maximum and displacement maximum are plotted, In order to compare the stress maximum and displacement maximum in different horizontal pressure and load. And the location of cracks, cracking load and ultimate load between test and finite element analysis and calculation are compared.In this thesis, the research of shear properties of dry joint key-tooth in precast segmental construction concrete bridge with external tendons presented some beneficial conclusions. It can give reference for related research and design and construction of the same type bridge in our country.