基于一阶优化方法的钢-混凝土组合索塔锚固区结构设计

Structural Design in Steel-concrete Composite Anchorage Zone on Pylon Based on First Order Optimization Method

研究了斜拉桥内置式钢锚箱钢-混凝土组合索塔锚固区的结构优化设计。建立以索塔锚固区典型节段的建造成本和水平承载力为综合目标的多目标优化模型,以索塔混凝土塔壁的厚度、钢锚箱侧板尺寸、塔壁配筋为设计变量,建立设计变量与满足塔壁裂缝宽度、塔内钢筋配筋率、钢锚箱屈服强度要求的状态变量之间的约束关系,采用一阶优化分析方法确定钢-混凝土组合索塔锚固区最优结构尺寸,得到了钢-混凝土组合索塔锚固区设计的最优方案。优化结果显示:针对索塔锚固区的钢锚箱侧板与混凝土塔壁形成的组合结构承受斜拉索水平力的特点,建立以建造成本和水平承载力为综合目标的优化模型是合理的,充分发挥了钢材和混凝土两种不同材料的性能,有效的控制塔壁混凝土裂缝产生。

The structural optimization design for composite anchor zone with build-in steel box of cablestayed bridge is studied. The Multi-objective optimization model is established for the cost of single segment in anchor zone and the horizontal bearing capacity. Taking the thickness of the concrete pylon wall, side-plane size of steel-anchor-box, reinforcement diameter in pylon wall as design variables, constraint relations are defined among the crack width of wall, reinforcement strength in pylon, reinforcement ratio and the yield strength of the steel-anchor-box. The optimum structural dimension is determined by using first order optimization method. The result shows that based on the properties of the composite anchorage zone, the multi-objective optimization model targeted for the cost and the horizontal bearing capacity is reasonable, and the cracks of the concrete wall are elfectively controlled by combining the respective advantages of steel and concrete.