大跨钢-混凝土组合梁斜拉桥静动力特性研究

Study on Static and Dynamic Characteristics of Long Span Steel-concrete Composite Beam Cable-stayed Bridge

以椒江二桥主桥为背景,通过实桥荷载试验及精确有限元模型模拟,研究分析了大跨度组合梁斜拉桥的结构整体静动力特性。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;结构总体变形、应力等实测值与理论分析结果吻合;桥梁实测固有频率均大于理论值,实际结构的动力刚度大于理论刚度;横桥向偏心荷载下组合梁横隔板主应力在偏载侧近桥面板、箱梁底板处较大,且横隔板与顶、底板及腹板交接处主应力达到峰值;横桥向对称荷载下主梁顶底板剪力滞效应明显,其中混凝土桥面板纵向应力在腹板交接处的应力峰值约为初等梁理论分析结果的2倍,设计时应进行组合梁截面的局部应力分析。

The paper presents an analysis of static and dynamic characteristics of the long span steel-concrete composite beam cable-stayed bridge on the basis of the field load tests on Jiaojiang secondary bridge. The results show that the bridge is of good overall static properties and linear elastic characteristics under the planned load test conditions. A good agreement is achieved between the experimental and analytical results, such as deflections and stresses. In terms of the dynamic load characteristics, the structural dynamic stiffness is greater than the analytical stiffness in the basis of the result that the measured natural frequencies are higher than the theoretical value. It is found that the principal stress of the diaphragm near the top and the bottom of the girder at the related side is greater under eccentric load, especially at the junctions of diaphragm and the girder compared with other sites. The steel-concrete composite beam presents the phenomenon of shear lag effect obviously under symmetry load, and the longitudinal stress at the junction of the concrete deck and girder webs is about two times of the results based on the elementary beam theory.