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根据混合梁斜拉桥的结构特点,考虑混凝土主梁和钢主梁结合处弯矩的限值,利用有限元方法建立混合梁斜拉桥成桥索力的优化模型.以塔梁的弯曲和拉压应变能之和为目标函数,以斜拉索的初张力为设计变量,成桥索力和主梁钢混结合处的弯矩为约束条件,结合ANSYS优化模块中的零阶和一阶方法进行求解,确定合理成桥状态下的索力.在优化过程中,改变结合处弯矩的限制范围,分析成桥下的内力和位移随限制范围变化的规律.通过一座单塔斜拉桥算例计算表明:将弯矩限值控制在0.3～0.5倍的主梁最小和最大弯矩范围内,得到的成桥状态最合理.索力从塔至边墩呈均匀增长趋势,主梁弯矩图变化平顺,结合处弯矩较小.
According to the structural characteristics of the hybrid cable-stayed bridge, considering the limit of the bending moment of the concrete girder and the steel girder, finite element method is used to establish the optimal model of cable force of the hybrid cable-stayed bridge. The sum of strain energy is the objective function. Taking the initial tension of the stay cable as the design variable, the bending force of the bridge cable force and the steel-concrete mixing of the main girder as the constraint condition, the zero order and the first order method in ANSYS optimization module In the process of optimization, the limit range of the bending moment at the joint is changed, and the law of the internal force and displacement under the bridge is analyzed as a function of the limit range.An example of a single tower cable-stayed bridge The calculation results show that it is most reasonable to control the bending moment within 0.3 ~ 0.5 times of the minimum and maximum bending moment of the main girder, and the cable force tends to increase uniformly from tower to edge pier, Changes smoothly, with a small bending moment.