千米级斜拉桥结构静力行为试验研究

Mechanical Behavior of Kilometerlevel Cablestayed Bridge Under Static Loads

摘要:

以苏通大桥斜拉桥为背景,通过实桥荷载试验及理论分析,研究千米级斜拉桥在静力荷载作用下结构的整体力学行为.研究表明,在相当于设计汽车荷载水平的试验荷载下,大桥结构处于线弹性工作状态,变形增量与荷载增量呈线性关系;结构总体变形、应力、索力的理论与实测结果较接近,中跨跨中最大挠度达1.388 m,梁端最大位移达0.107 m,塔顶最大位移达0.222 m;试验荷载下钢梁应力水平较低,受剪力滞效应、横坡及车轮局部效应等影响,钢梁顶、底板应力沿横截面呈纵向应力不均匀分布,尤其顶板U肋出现拉压应力交替现象.这在钢箱梁疲劳损伤评估中值得关注.

Abstract:

The paper presents a numerical analysis of the global mechanical behaviors of Sutong Bridge of China on the basis of the field static load tests.The results show that the bridge under the planned load test conditions is of good overall static properties and linear superposition characteristics, and incremental deflection is observed to be linearly proportional to incremental load. A good agreement is achieved between the experiential and analytical results such as displacements, stresses and cable forces. It is found that the measured maximum static deck deflections at the span centre is 1.388 m, maximum horizontal displacement of towers is 0.222 m, and maximum horizontal displacement of main girder is 0.107 m. Moreover, the stress level of the steel box girder under static loads is low, the longitudinal stress distributions of the slab and floor beam are nonuniform,the reasons for these phenomena include the shear lag effect and the influence of transversal slope of steel box girder as well as local stress effect of wheel load. And the Ushape ribs are of critical importance in fatigue damage assessment because of its alternating tensioncompression stresses.