计入几何非线性影响的斜拉桥施工索力的确定

Calculation of Cable Forces under Construction for Cable Stayed Bridges Considering Structural Geometric Non-linearity

考虑缆索垂度效应、加劲梁的梁柱效应及节点大位移效应等几何非线性因素对大跨度斜拉桥施工索力的影响,模拟正装和虚拟退拆施工过程,建立了施工索力计算的继承与迭代关系.利用通用有限元程序,建立斜拉桥全桥三维有限元模型,合理划分荷载步和荷载子步,通过倒拆正装反复迭代,得出了施工索力及相应的成桥线形.使用最小二乘法修正倒拆与正装之间的差值,有效地计入了几何非线性的影响,使斜拉索满足成桥状态所要求的索力并使主梁以要求的精度接近理想的成桥线形.

For the cable force calculation of long-span cable stayed bridges,the construction procedures of forward erection and virtual backward erection were simulated and the inheriting and iteration expressions of cable forces under construction were established, taking account of geometric non-linearity including sag effect of cables, P-Δ effect of stiffening girders and large displacement effect of nodes. The 3D model of an actual cable stayed bridge was established based on a general FEM program. The cable forces under construction and the corresponding profile of completed bridge were attained through rational load steps and sub-steps division and iteration of backward-forward erections. The demanded cable forces of completed bridge stage are satisfied, and also the stiffening girders approach the appointed profile of completed bridge by required precision, after modified the differences between backward and forward erections by the least square method to consider the effects of geometric nonlinearity effectively.