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为确定四索面钢箱梁斜拉桥的合理施工状态,先以构件弯曲、扭转应变能之和为目标函数,将多索面斜拉桥的索力优化问题转变为求解线性代数方程问题,并导出合理成桥状态空间索力及外内侧拉索索力比值;再以该合理成桥状态空间索力为目标索力,通过正装迭代法确定四索面钢箱梁斜拉桥合理施工状态;最后以嘉绍大桥(六塔四索面斜拉桥)为工程算例,建立该桥同一纵向位置等索力、空间索力2种空间模型,对比分析2种四索面钢箱梁斜拉桥模型的合理施工状态及其空间结构效应,以验证该方法的正确性。研究结果表明:四索面钢箱梁斜拉桥拉索空间效应显著,外内侧拉索初拉力比值分布较离散,近塔、墩处结构构造和受力较为复杂,其索力比值略大于1,其余标准梁段处索力比值为0.85~0.97;采用等索力模型会导致主梁内存在较大扭矩,横梁内存在较大弯矩等不利受力状态,索力优化后的空间结构计算模型的主梁扭矩、横梁弯矩均得到了改善;钢箱梁斜拉桥施工控制应以主梁线形控制为主,索力和应力控制为辅,对于结构受力复杂的塔梁交界处及边跨附近,应对其局部采取应力控制措施,以防止局部屈曲。提出的方法同样适应于其他类型多索面斜拉桥合理施工状态的确定。
In order to determine the reasonable construction state of cable-stayed bridge with four-girder steel box girder, the objective function of the sum of bending and torsional strain is taken as the objective function to change the cable force optimization problem of multi-cable face cable-stayed bridge to solve linear algebraic equation. And then derive the ratio of reasonable cable space and external cable tension force; then take the space cable force of reasonable bridge state as the target cable force, and determine the reasonable construction status of cable-stayed bridge with four-cable girder through the formal fitting iteration method; Finally, taking Jia Shao Bridge (six tower and four cable plane cable-stayed bridge) as an example, two kinds of space models of cable force and space cable force at the same longitudinal position of the bridge are established, The reasonable construction status of the bridge model and its spatial structure effect to verify the correctness of the method. The results show that the cable effect of cable stayed bridge with four girder steel box girders is remarkable, and the distribution ratio of initial tensile force of outboard inner cables is more discrete. The structure and stress of pylon near the pier and the pier are more complex, , The other standard beam section at the cable force ratio value of 0.85 ~ 0.97; the use of equal cable force model will lead to the existence of a large torque within the main beam, the beam there is a large bending moment and other adverse conditions, the optimization of the spatial structure of the cable force calculation The model girder torque and beam bending moment are all improved. The construction control of steel box girder cable-stayed bridge should be dominated by the linear control of the main girder, supplemented by the cable force and the stress control. For the complex girder junction and The edge of the cross, the local stress control measures should be taken to prevent local buckling. The proposed method is also suitable for the determination of reasonable construction status of other types of cable-stayed bridge.