Analysis And Reserrch Of Construction Technology On Large-Scale Prestressed Reaction Wall

Reaction wall is an important experiment establishment in structural laboratory, it through the horizontal hydraulic loading device fixed on the wall applying horizontal load on the specimen. Reaction wall with counterforce floor can undertake all kinds of engineering structure pseudo dynamic test and static test of large tonnage, such as large scale building model or full size component seismic performance research. The research on civil engineering new structures, new techniques, new materials research has important significance. Reaction wall as a test facility has been well known, but the current results of reaction wall study are relatively little lack of related literature and design specifications, procedures for reference. Therefore it is still a worthy of discussion and a very realistic topic about how to guarantee the reaction wall construction precision and quality.The engineering background of this paper is a large prestressed reaction wall system under construction of southeast university large structures laboratory multidimensional loading experiment platform. According to research and analysis about massive concrete crack control of laboratory floor, tension programs of vertical and transverse prestressing steel bar in reaction wall and reaction wall and pedestal construction precision control of the reaction wall under construction, the research conclusion solve some problems in the project construction to ensure the engineering construction quality. The main research work and achievements are as follows:(1) According to the existing experience formula and engineering data, this paper calculates and analyzes each component project construction parameters including floor massive concrete temperature field and temperature stress, reaction wall template design, and elongation of prestressing reinforcement.Calculation and analysis results show that the floor massive concrete construction scheme can satisfy the demands of the massive concrete temperature and crack control, reaction wall template design meet the requirements of strength, stiffness and overall stability, and elongation of prestressing reinforcement can be used to check tensioning process.(2) Using finite element analysis software Midas Gen, this paper carries out finite element simulation of reaction floor temperature field and analyzes the simulation results to realize comprehensive understanding of the floor massive concrete temperature field distribution and change rules.With the massive concrete engineering of structure laboratory floor, summarize the floor temperature crack control measures by raw material of concrete, mix proportion, concrete placement, heat preservation and moisture conservation, temperature monitoring. And it is verified that the optimized construction scheme is accurate by check and evaluation.(3) According to the distribution characteristics of the unbonded tendons in reaction wall, this paper respectively put forward five different tensioning schemes for horizontal and vertical prestressing tendons by batched tension process. Using the finite element analysis software Midas Fea finite simulate calculation in the construction stages by activating stressed tendons and prestressed load in stages to Simulate the tensioning process. According to the analysis of the simulation results about prestress loss, the deformation and stress of reaction wall, uniform degree of cross-section and tendons stress distribution of each scheme in the process of tensioning, this paper thrown up that the optimal tension scheme of vertical prestressed tendons of each wall is symmetrical tension from the middle to both sides and the optimal tension scheme of horizontal prestressed tendons of each wall is tension from the bottom in turn. According to the optimal plan of the prestressed tendons in each direction, the two way prestressed tendons are composed of two different cases, which are vertical rear horizontal and horizontal rear vertical. By comparing and analysis, the optimum tension sequence is the horizontal rear vertical. The first partial tension is horizontal prestressed tendons and the post partial tension is vertical prestressed tendon.(4) During the construction of large-scale prestressed reaction wall, this paper studies and analyzes of various aspects of the construction process. It adopts diverse measures to control the construction quality, about error control and detection of correction including installation of steel skeleton, production, positioning and welding, template installation of load hole, erection of formwork, concrete placement and ensure construction quality and accuracy of reaction wall and pedestal.