Research On Topology Optimization Of Steel-concrete Joint Section Of Bridge Tower Based On Improved BESO Method

Topology optimization can obtain the optimal structural form under the given objective function and constraints,and provide designers with innovative structural design.This technology has broad application prospects in the fields of machinery manufacturing,aerospace,and civil engineering.Bi-directional evolutionary topology optimization(BESO method)is one of the most commonly used methods in topology optimization because of its simple theory,easy programming and practicability.At present,the BESO method uses fixed removal ratio for optimization calculation,which has low efficiency and low stability.Aiming at this problem,this paper proposes an improved BESO method based on multi-factor dynamic removal ratio.The topology optimization of the steel-concrete joint section of a Super-kilometer main span multitower cable-stayed bridge is studied.The main work is as follows:(1)The influence of structural volume fraction and stress uniformity on the removal ratio in BESO method was analyzed,and multi-factor dynamic removal ratio calculation formula considering the two factors was established.An improved BESO method based on the multi-factor dynamic removal ratio was proposed.The results show that the calculation efficiency of the improved method is improved by 14%～27%compared with the traditional BESO method,and the stability is higher and the optimization quality is better.(2)An improved BESO method optimization procedure was developed.Through the secondary development of ANSYS APDL and MATLAB functions,the program implementation framework of the improved BESO method is proposed,and the optimized program is established through four modules,and the improved BESO method is realized.The program is simple in operation and high in practicability,and can perform topology optimization design of arbitrary two-dimensional and threedimensional structures.(3)Based on the optimization program,the improved BESO method is extended to three types of complex topology optimization problems,including multi-condition optimization,periodic structure optimization and multi-material optimization.The example analysis shows that the improved BESO method has higher optimization efficiency in solving the above problems.Compared with the fixed removal ratio BESO method,the optimization efficiency is improved by 13%～25%.At the same time,the mean compliance of the optimization results obtained is smaller,and the overall performance is better.The high quality fully demonstrates the superiority and broad applicability of the method.(4)Using the improved BESO method,the topology optimization of the steelconcrete joint section of a Super-kilometer main span multi-tower cable-stayed bridge is carried out,and the optimal design scheme is proposed.The finite element calculation results show that under the most unfavorable working conditions,the peak value of concrete stress in the joint section of the optimal design scheme is reduced by30% compared with the preliminary design,and the problem of stress overrun is solved.At the same time,the stress distribution is more uniform,and the mechanical performance of the joint section is improved.This study provides a meaningful reference scheme for the optimal design of the steel-concrete joint section of the bridge tower.