斜拉桥索塔塔冠区应力分析及优化

以塔冠区为例,研究预应力混凝土索塔锚固区应力优化设计的方法。对塔冠区锚固段进行有限元分析。以反映预应力筋张拉量的张拉系数为设计变量,以预应力筋的强度和结构裂缝宽度为约束条件,以裂缝平均宽度和标准差最小为目标函数,建立锚固段危险区域应力优化数学模型,并在ANSYS软件平台上,利用零阶和一阶优化方法获得设计变量的最优解。分析结果表明:齿板凸起处和齿板交接处是锚固区的危险区域,其第一主应力均超过了允许值;通过减小环向预应力张拉量可改善危险区域应力情况。优化结果表明,采用自上而下逐渐减少的环向预应力张拉量,索塔应力的分布状态更加合理。

Stress Analysis and Optimization of Cable Tower Crown Area in Cable-Stayed Bridge

Taking the top segment of the pylon (TSP) as an example, optimum design method for anchorage zone of prestressed concrete pylon is studied. The stress distribution of the TSP had been analyzed and results showed that the protruding areas of anchor blocks and the junctions of anchor blocks were dangerous areas for their major principal stress beyond the permission. Therefore, the optimum design guideline was decided, which aim to reduce the major principal stress of these areas. And then, comparisons of two methods for reducing the major principal stress had been conducted. The method with decreasing the force of ring prestressed tension was found to be simple and effective and was selected to be used in the optimum design. Based on the analysis above, a mathematical model of the major principal stress optimization for the dangerous areas, which was formulated to consider the stretch coefficient, proposed in this paper to index the tension force, as design variables, the strength of the prestressed tension and the crack width as the constraints and the minimization of the mean and the standard deviation of crake width as the objective function, was set up and solved by zero-order and first order approximations.