Key Technology For Quality Control Of Steel-concrete Section Of Large-span Rigid-frame Bridge

The engineering background of this dissertation is that I was responsible for the construction of the Zhongshan Xiaolan Waterway Composite Continuous Rigid Frame Bridge during my in-service engineering master’s degree.In view of the current engineering status of difficult construction quality control of steel-concrete joints of long-span rigid frame bridges,the thesis carried out research on two aspects of special concrete and construction technology for joint construction,and obtained the following research results:(1)Based on the design principle of the self-compacting concrete mix ratio,in view of the complex internal structure but large size of the steel-concrete joint section,on the basis of the C55 concrete mix ratio of the original concrete beam section,the selection of raw materials is not changed,and the sand ratio,mineral admixture,The influence of fiber,expansion agent and other factors on the performance of concrete,a concrete mix ratio suitable for the construction of steel-concrete joints is selected.(2)The mixing ratio of C55 concrete for construction in steel-concrete combination section is:Cement 427kg/m~3,fine aggregate640kg/m~3,coarse aggregate 1050kg/m~3,water 165kg/m~3,slag powder85kg/m~3,expansion agent 57kg/m~3,water reducing agent 12.52kg/m~3,polyacrylonitrile fiber 1.0kg/m~3.The extension of fresh concrete is controlled to be 500mm～550mm,and the construction performance is kept at 1 hour.The construction performance is good,and the mechanical properties and durability meet the requirements of the specification.(3)Take the lead in designing and using the rigid framework of the steel-concrete joint section,which solves the longitudinal and lateral unbalanced displacement caused by the weight of the concrete during the hoisting process of the steel-concrete joint section,ensuring the construction accuracy of the joint section.(4)The high-precision placement of steel-concrete composite section is realized and the overall construction quality of the bridge is ensured through the design of the rigid skeleton of the composite section,the overall synchronous lifting technology of the composite section,the monitoring of the stiffness and deformation of the hanger and foundation,and the cooperative construction of the concrete pouring construction of the composite section.(5)Through the construction quality monitoring and detection of the bonding section,it is shown that there are no concrete micro-cracks,no hollow between steel cell and self-compacts concrete and other quality problems in the bonding section,the bridge surface line is smooth and the structure line meets the design requirements.As an important part of"Key Technology Research of Long-span Composite Steel Structure Bridge",the research results of this dissertation won the third prize of Science and Technology of China Highway SocietyIn summary,the research results of this paper have certain guiding significance for the construction quality control of steel-concrete joints of long-span rigid frame bridges in the future.