Determining The Reasonable State Of Cable-stayed Bridges Based On Multi-objective Particle Swarm Optimization Algorithm

For more than 60 years since the birth of the modern cable-stayed bridge,cable-stayed bridges have been widely used and have become one of the most competitive bridge types in the range of 200 to 1100 m.The vigorous development of cable-stayed bridges also poses higher requirements and challenges for the design and construction of cable-stayed bridges.Aiming at the problem of cable force determination in cable-stayed bridge design and monitoring calculation,namely,reasonable bridge state and reasonable construction state determination,this paper is based on multi-objective particle swarm optimization(MOPSO)algorithm and "two-in-one technique" for cable-stayed bridge cable.Force determination and optimization issues are studied.The main work and results are as follows:(1)The basic concepts of multi-objective optimization problems and the common methods for solving multi-objective optimization problems are reviewed.The MOPSO algorithm is introduced in detail.Based on the standard particle swarm optimization algorithm,the external reserve set and optimization update strategy are added.Adapt to the optimization problem of multi-objective and multi-constraint.(2)Introduce the "two-in-one technique" of determining the reasonable state of the bridge and the construction state of the cable-stayed bridge,and compare it with the traditional method of determining the reasonable bridge state and then determining the reasonable construction state.The method has a small calculation amount.The concise features of the concept.The basic principles for determining the cable force of cable-stayed bridges are determined:structural safety,straight beam tower,uniform cable force and minimum number of cables.(3)Based on the MOPSO algorithm and the "two-in-one technique",an automatic optimization method for cable tension of cable-stayed bridges is proposed.Compared with the traditional single-objective cable force optimization method,there is only a single solution limitation.The method considers multiple objective functions and multiple constraints.The obtained Pareto optimal solution set can be further filtered by decision makers based on experience.The automatic optimization program based on this method is written by using Python programming language and finite element software to realize the automatic optimization of the initial cable force of the cable-stayed bridge.(4)Using the prepared cable force automatic optimization program,take an asymmetric hybrid beam single tower cable-stayed bridge,a double-tower composite beam cable-stayed bridge and a three-tower composite beam cable-stayed bridge as examples to calculate,select the main The sum of the bending strain energy of the tower and the main beam,the square of the longitudinal bridge displacement under the dead load of the main tower is taken as the objective function,and the construction process and the structure after the bridge are in a safe state and the overall distribution of the cable force is uniform.Restrictions.The optimization results of engineering examples show that the proposed method can quickly find the Pareto optimal solution set and select the optimal solution.The structural stress is in the safe range,the main tower is linear and the overall cable distribution is uniform.