Structure Analysis And Optimization Of A Large Navigation Aqueduct Made Of Thin-walled Box Girder

With the development of economy and construction of infrastructure projects in central and Western China,aqueduct is used more and more widely.The aqueduct plays a key role in solving the problems of farmland irrigation,Water resources development and utilization,and transportation of inland waterway in china.The safe operation of the aqueduct is an important guarantee for the sustainable development of our economy.Because of the important function of aqueduct structure,it is necessary to do further research on the design and construction technology of aqueduct structure.Based on a navigation aqueduct belongs to the oversize hydropower project in Guangxi province,which is 110m long and navigable depth is 3.0m,the largest designed ship type is 500t class,the left and right half aqueduct are symmetrical,and the upper box girder of the aqueduct is a thin-walled structure.The study on the structural response of the large aqueduct structure under the action of common dynamic and static loads was carried out by calculation,the aqueduct was study and optimize by using the finite element software ANSYS,the calculation results have important guiding significance for the design and construction of the project or similar projects.(1)According to the conditions of the research object,the difficulty of structural calculation is briefly analyzed,and loads considering in this aqueduct were simplified.Also the application methods of temperature action,earthquake action and dynamic water pressure in the large finite element software ANSYS were discussed.Three dimensional model of aqueduct stucture was established.Under the action of temperature,the temperature contour line is dense at the interior of the aqueduct close to the water surface,which will causes large load,and it should be take care in engineering design.Under the action of earthquake,the natural frequency of vibration of the aqueduct fill with water is higher than empty aqueduct,the effect of seismic load on the bearings of 1/4 and 3/4 section are very large.(2)Based on the stress characteristics of aqueduct structure,stress and strain of 5 typical sections were selected as key research targets.The distribution of stress and strain of the aqueduct under the state of dynamic,static and empty aqueduct were calculated and analyzed by using ANSYS software.The nonlinear calculation results show that the aqueduct structure meets the design demands under the static forces condition and the empty condition.While considering the action of earthquake,the aqueduct gets into nonlinear state under the action of combination of dynamic and static,the tensile stress exceeds the design demand.(3)The safety of the aqueduct are taken as a target,and the aqueduct structure is optimized by using ANSYS software.Using the optimize function of ANSYS software,the maximum first principal stress at 1/2 section of the aqueduct was taken as the objective function,and the control force of the whole steel strand on both X and Z axis were taken as design variables.Then check the result by using ANSYS software,the results show that the structure meets the design requirements,thus the optimized design scheme was feasible.