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考虑混合梁斜拉桥钢混主梁结合处的弯矩及恒活载作用,综合3种单一的索力优化方法,采用3步法进行成桥状态下的索力优化,确定最优成桥状态。首先以主梁钢混结合处的弯矩和成桥索力为约束条件,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,进行有约束的恒载索力优化;再引入活载作用,采用内力平衡法,确定主梁各控制截面的弯矩可行域;最后以塔的最大水平变位最小为目标函数,以成桥索力和控制截面的弯矩可行域为约束条件,优化得到成桥索力。结合混合梁斜拉桥实例,利用有限元方法建立成桥索力的优化模型,采用ANSYS优化模块进行求解。计算结果表明,混合梁斜拉桥的索力优化3步法合理可行,可以全面考虑恒活载及结合处的弯矩,优化后的索力呈均匀变化趋势,主梁的强度储备安全,梁和塔变形小。
Considering the bending moment and constant live load at the joint of the steel-concrete composite girder of hybrid girder cable-stayed bridge, three kinds of single cable force optimization methods are adopted, and the cable force optimization under the bridge state is carried out by 3-step method to determine the optimum bridge status. First of all, the bending moment and cable tension at the steel-concrete mixing point of the main beam are used as the constraint conditions. The objective function is the sum of the bending and compressive strain energy of the tower girder, and the initial tension of the stay cable is taken as the design variable. Then, the live load is introduced and the internal force balance method is adopted to determine the feasible region of the bending moment of each control section of the main girder. Finally, taking the minimum horizontal displacement of the tower as the objective function, The bending moment of the cross-section can be used as the constraint condition, and the cable tension can be optimized. Combined with the example of the hybrid cable-stayed bridge, the finite element method was used to establish the optimization model of the bridge cable force, and the ANSYS optimization module was used to solve the problem. The calculation results show that the cable force optimization of the hybrid cable-stayed bridge is reasonable and feasible by three-step method. The bending moment of the joint can be fully considered. The optimized cable force shows a uniform trend. The strength of the main beam is safe to be stored. Small deformation of the tower.