Research on Structural Optimization of Cable Beam Anchorage Zone Based on Improved NSGA-Ⅱ and IGA-BP Neural Networks
In order to achieve structural optimization of the steel anchor box in the cable beam anchorage zone of a large-span cable-stayed bridge,a structural parameter optimization method based on the NSGA-Ⅱ algorithm and IGA-BP neural network model is proposed based on the actual engineering of the cable beam anchorage zone structure of a large-span cable-stayed bridge.Firstly,the topology structure for predicting the response data of the steel anchor box was determined based on the BP neural network.An adaptive cross mutation improved genetic algorithm was used to adjust the weight threshold of the neural network prediction model for the response of the steel anchor box structure,and an IGA-BP neural network prediction model that meets the fitting accuracy requirements was obtained.Then,a mathematical optimization model was established considering the average stress of the structure and the peak stress on the main plates.The NSGA-Ⅱ algorithm with improved crossover and mutation operators was used to design the optimization process for the parameters of the steel anchor box structure.Finally,the NSGA-Ⅱ algorithm and IGA-BP model were jointly improved to optimize the structural parameters of the steel anchor box.The results show that the adaptive genetic algorithm has a good effect on adjusting the weights and thresholds of the BP neural network.Compared to the standard BP neural network,the IGA-BP neural network has higher fitting accuracy and training efficiency;The improved NSGA-Ⅱalgorithm can optimize the structural parameters of the steel anchor box.According to the Pareto coordinated optimal solution,the thickness of the steel anchor box support plate and pressure bearing plate increases to a certain extent,while the thickness of the stiffening plate and anchor pad plate slightly decreases;The average stress reduction on the optimized structure is about 2.7％,with the peak stress of the bearing plate decreasing from 200.9 MPa to 178.1 MPa,a decrease of about 9.5％.The peak stress of the support plate decreasing from 199.6 MPa to 179.5 MPa,a decrease of about 10.07％.After optimization,the peak stress in the high stress area of the structure was significantly reduced,and the distribution of medium stress areas was larger than before,which to some extent improved the phenomenon of structural stress concentration and verified the feasibility of this method.
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维普
