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针对网架结构抗震设计,提出一种基于多目标进化算法NSGA-Ⅱ的抗震优化设计方法。建立以网架用钢量最小化和结构最大竖直位移最小化为目标的多目标优化模型;结合有限元动力计算模型和显式动力分析方法对网架结构进行地震响应分析;考虑到优化模型带有约束条件以及设计变量的特点,提出基于NSGA-Ⅱ的改进算法NSGA-Ⅱ+,采用该算法来求解优化模型。为了验证算法改进效果,对经典的空间桁架结构进行了优化,并与其他算法的优化结果进行比较,结果表明改进算法具有良好的收敛性和稳定性。最后以ANSYS/LS-DYNA为结构动力分析工具,混合编程实现了一个斜放四角锥网架的多目标抗震优化设计。优化实例表明,该方法能得到优质解,具有实际工程意义。
Aiming at the aseismic design of the truss structure, a seismic optimization design method based on multi-objective evolutionary algorithm (NSGA-Ⅱ) is proposed. The multi-objective optimization model with the goal of minimizing the amount of steel used in the grid and minimizing the maximum vertical displacement of the structure is established. The seismic response analysis of the grid structure is carried out by combining the finite element dynamic calculation model and the explicit dynamic analysis method. Considering the optimization model With constraints and design variables, the improved NSGA-Ⅱ based NSGA-Ⅱ + algorithm is proposed to solve the optimization model. In order to verify the improvement of the algorithm, the classical space truss structure is optimized and compared with other optimization results. The results show that the improved algorithm has good convergence and stability. Finally, ANSYS / LS-DYNA is used as structural dynamic analysis tool to realize the multi-objective seismic design optimization of a diagonal square pyramid grid. The optimization example shows that this method can get a good solution and has practical engineering significance.