基于遗传算法的脊杆索穹顶优化设计

为了降低实际工程中索穹顶结构的造价,提出了一种基于遗传算法的优化设计方法,将预应力倍数和构件截面作为离散设计变量,在目标函数中考虑了结构的施工张拉程度.以Geiger和Levy两种索穹顶作为算例,得到了在多种荷载工况下满足结构应力和位移约束的索穹顶最小造价,并研究了预应力对优化结果的影响.将索穹顶的脊索替换为可受压的钢杆后,对改进方案——脊杆索穹顶进行了优化设计,并与原结构对比了结构造价和力学性能.结果表明:该方法能够高效准确地得到造价最小的索穹顶结构,各构件内力比较接近其极限设计状态;有必要在索穹顶的设计过程中考虑预应力分项系数和活荷载不均匀分布等因素,以满足结构稳定性和单根构件承载力的要求;采用钢杆替换脊索,使索穹顶结构的总造价稍有降低,并显著降低了结构挠度和支座反力.

Optimization Design of the Ridge-bar Cable Dome Based on Genetic Algorithm

A genetic algorithm based optimization scheme was proposed to reduce the cost of cable dome structure in practical engineering. The prestress coefficient and member sections with specified profiles were defined as discrete design variables, and structural tensioning level was considered in the object function. Taking Geiger and Levy cable domes as two examples, the minimum cost design was obtained which satisfied constraints of structural stress and displacement in a variety of load conditions, and sensitivity analysis was adopted to study the influence of prestress on optimization results. The optimization process was also carried out for an improved structural plan, ridge-bar cable dome, in which the ridge cables were replaced with steel bars capable of bearing compression, and the structural cost and mechanical properties of improved plan were compared with the original cable dome structure. Results show that the optimization method can gain the minimum cost design of cable dome effectively and accurately,and the internal force of all members are closed to their limit state. To guarantee the structural stability and bearing capacity of different members, it is necessary to consider the partial factor of prestress and non-uniform distribution of live load in the design process of cable domes. Adopting steel bars instead of ridge cables can slightly lower the total cost of cable dome and significantly reduce the deflection and reaction force.