Prestress Drawing Process Effects On Continuous Rigid Frame Bridge

Prestressed tension is very important as the critical part of the construction process of continuous rigid frame bridge..At the same time, it is a very important work in the bridge monitoring.The quality of prestressed tension direct influence bridge alignment control and box girder stress reserves.In order to ensure a safe bridge construction process、a safe state of construction and the quality of bridge, avoid quality problems because of the construction problems of prestressed tension, we need to pay more attention to the prestressed tension.Measureing the indicators of the prestressed tension effect is the size of the effective prestress which is subjected to many factors, only with these conditions can ensure the prestressed tension quality:appropriate construction technology of prestressed tension、high quality of prestressed materials、compliance requirements of tensioning equipments、correct operating procedures and skilled operative technique.in the actual construction of bridge, This phenomenon can often be seen that prestressed tension does not meet specifications,such as asymmetric tension. It brings more or less influence on bridge construction, some difficulties to bridge monitoring、bridge linear controling and box girder stress controling,and even security risks to bridge construction, Therefore, it is necessary and has a important practical significance to study the technology of prestressed tension.The research background is a bridge in our contury, During the bridge monitoring work,All aspects of bridge construction and material datas were collected which are prepared for writing papers. This thesis is focused on the concrete elastic loss of prestress, established the formula of the loss of elasticity of concrete in the construction process ofasymmetric prestressed tension prestressed, analoged the bridge construction by using the finite element software Midas/Civil.Established different program models of symmetric tension and asymmetric tension technology based on different tension sequence.by adjusting the tension age, changing the tension sequence.Different options are conducted a comprehensive comparison from three aspects:Concrete elastic loss of prestress、box girder prestressed balance and box girder cross-section stress distribution.The purpose of the comparison is to prove the prestressed asymmetric tension feasibility in theory and select the best tensioning program from the asymmetric tension of several programs.the last chapter is included as a separate chapter to research on these problem of prestressed serious loss and investigate layout principles of prestressed steel beam Through repeated attempts and calculations to explore the sensitivity of the friction coefficient proposed a way to attempt to compensate for loss of prestress and improve the box girder Stress conditions, such as adjusting the prestressing steel beam layout increaseing the prestressed reinforcement.Thesis results have guidance and reference to design and construction control continuous rigid frame bridge, it can be used to improve the prestressed asymmetric tension effect, ensure the bridge has sufficient reserve of stress and good linear, thus the bridge can be closed successfully.