Optimization Design And Analysis Of Mechanical Properties Of Large Double Wall Steel Cofferdam Structure

With the rapid development of economy in our country,long-span bridges across rivers and rivers are constantly being built.New materials,new technologies and new technologies have been continuously applied in the process of bridge construction,and the application of large double-wall steel cofferdam structure in the bridge construction has become more and more frequent.In this paper,a large double-wall steel cofferdam structure in northwest China is taken as the research object,based on the development and research status at home and abroad,combined with the structural characteristics of the bridge large double-wall steel cofferdam structure and using environment,with the help of large finite element program,the whole and local mechanical performance of the bridge large double-wall steel cofferdam is analyzed.Combined with the response surface method,the design and optimization of the bottom concrete thickness of the existing double-wall steel cofferdam structure is carried out.The main research contents and conclusions are as follows:1.Taking the large double-wall steel cofferdam structure of a Yellow River Bridge in Northwest China as the engineering background,considering the actual construction process in the field,four key construction joints are summarized,so as to establish four load conditions.Then the finite element simulation software Ansys is used to model the whole structure,and the mechanical properties of large double-wall steel cofferdam structure are studied.The results show that the second stage of the working condition is the most unfavorable stress condition,the deformation and stress results are the largest,and the vertical stiffener and partition plate are prone to stress concentration,which is the potential dangerous area of local yield of the structure,and it should be strengthened and prevented accordingly;2.Based on the large double-wall steel cofferdam structure in the engineering background,under the condition of the most unfavorable load condition,the influence of each parameter on the mechanical performance of the double-wall steel cofferdam structure is studied by changing the thickness of the inner and outer panels,the vertical spacing between the horizontal annular plate and the transverse bracing,and the specification of the vertical stiffener.The results show that the thickness of inner and outer panels and the spacing of annular plates have great influence on the overall deformation and stress results,and the local yield can be effectively avoided by increasing the vertical stiffener.These conclusions provides a theoretical reference for the design optimization of large double-wall steel cofferdam structures.Under the comprehensive comparison,the parameter setting in the actual project is more reasonable and economical.3.The local simulation analysis model of the sealed concrete part is established,and the strength and anti-floating stability of the sealed concrete structure are checked and calculated by using the traditional empirical method and the finite element simulation method,respectively.Under the principle of safety and reliability,in order to achieve the purpose of reducing cost and increasing efficiency,the design of sealed concrete of existing double-wall steel cofferdam structure is optimized by using the optimization design function of Ansys and response surface method.The thickness of optimized concrete is reduced by 29%compared with the original design,and the concrete material can be optimized from C30 to C25.