斜拉桥桥面板横向分析计算模型方法比较

Comparison of Calculation Models and Methods for Transverse Analysis of Cable-stayed Bridge Decks

摘要:

为比较斜拉桥桥面板横向分析中不同计算模型的差异，以嘉兴市快速路三期二阶段上跨沪昆铁路立交工程的独塔中央索面混凝土斜拉桥为工程背景，分别建立横向杆系模型、空间网格模型和实体模型，对比恒载、车辆荷载、预应力钢束作用以及三者组合共4种荷载工况下的桥面板横向应力分布。结果表明：在前3种荷载工况下，3种模型的桥面板应力正负和变化规律基本一致；与另外2种模型相比，横向杆系模型在恒载下的桥面板上下缘拉应力偏小，在车辆荷载下的应力极值偏大而在预应力钢束作用下的压应力偏小；在3种荷载组合的第4种工况下，横向杆系模型与实体模型的最大应力差为4.6 MPa，明显大于空间网格模型与实体模型的最大应力差1.7 MPa。横向杆系模型的应力结果相比另外2种模型偏保守，空间网格模型能够考虑箱梁一定的空间效应，与实体模型的应力差较小。

Abstract:

To compare the differences among various calculation models in the transverse analysis of cable-stayed bridge decks, taking the single-pylon central-plane concrete cable-stayed bridge of the Jiaxing Expressway Phase Ⅲ Stage Ⅱ Overpass crossing the Shanghai-Kunming Railway as the engineering background, a transverse bar system model, a spatial grid model and a solid model are established to compare the transverse stress distributions of the bridge decks under four loading conditions such as constant load, vehicle load, prestressed steel strand action, and their combinations. The results show that under the first three load cases, the positive and negative stresses and variation trends of the bridge deck in the three models are generally consistent. Compared with the other two models, the tensile stress at the upper and lower edges of the bridge deck of the transverse bar system model under the constant load is relatively small. The stress extreme value under vehicle load is relatively large, while the compressive stress under the action of prestressed steel strands is relatively small. Under the fourth condition of the three load combinations, the maximum stress difference between the transverse bar system model and the solid model is 4.6 MPa, significantly greater than the 1.7 MPa difference between the spatial grid model and the solid model. The stress results of the transverse bar system model are relatively conservative compared with the other two models. The spatial grid model can consider a certain spatial effects of the box beam, and the stress difference from the solid model is relatively small.