钢桁架拱桥的结构优化分析

Structural optimum design of steel trussed arch bridges

为优化钢桁架拱桥的结构设计,利用ANSYS有限元软件的APDL二次开发功能,建立参数化钢桁架拱桥模型,开发影响线计算程序.利用影响线求解桥梁结构最不利活载位置.通过灵敏度分析将优化设计与可靠度分析联系起来,以桥梁结构关键构件和关心位置最大轴向应力和最大竖向位移为状态变量,以截面尺寸为设计变量,并以全桥自重为目标函数,将基于可靠度的结构优化与传统结构优化进行对比.结果表明,基于可靠度的钢桁架拱桥优化结构可以节省大量计算时间和空间,并有效减轻桥梁的自重,改善结构受力.

The secondary development APDL of ANSYS FEM software was used to build parametric model of the deck type steel trussed arch bridge and develop influence lines programs so as to optimize the structure design of steel trussed arch bridges. The most unfavorable positions of load with the influence lines were calculated. Through relating the optimum design with the reliability analysis and the sensitivity analysis, and taking the maximal axial stress and maximal vertical displacement as state variables, the sectional dimension as design variables, as well as the weight of the bridge as good function, thereby comparing with the traditional structural optimum design, the structural optimum design based on the reliability theory can save much calculation time and computer memory space, which effectively reduce the weight of the bridge and improve its capacity.