超宽三塔斜拉桥结构静动力行为试验研究

Experimental Study on Static and Dynamic Behaviors of Ultra-wide Three-pylon Cable-Stayed Bridge

摘要:

为研究超宽三塔斜拉桥结构的整体静动力行为，以主跨176 m、桥面宽57 m的西安沣邑大桥为背景，开展了实桥荷载试验研究。基于静载试验获得了结构变位与关键位置的应力变化，采用无障碍行车与有障碍行车试验研究了结构冲击系数的变化。结果表明：圆形截面独柱塔刚度效应及几何非线性明显，在最不利静力荷载作用下，三塔斜拉桥的主梁及主塔位移较大，且中塔变形大于边塔变形；同时，超宽钢箱梁剪力滞效应明显，在最不利静力荷载作用下，主梁截面应力分布非常不均匀，且受横坡及局部荷载效应影响显著。另一方面，超宽三塔斜拉桥的应力冲击效应非常明显，在行车及有障碍行车情况下，钢梁顶底板的应力冲击系数最大为0.29，这表明，实际运营中应关注桥面铺装的损伤，避免跳车带来的影响。

Abstract:

To study the overall static and dynamic behaviors of an ultra-wide three-pylon cable-stayed bridge structure, taking the Xi'an Fengyi Bridge with the main span of 176 m and deck width of 57 m as the background, a full-scale load test study is conducted. The structural displacement and the stress variations at critical locations are obtained through static load tests, while the unimpeded and impeded vehicle running tests are performed to study the variations in structural impact coefficients. The results demonstrate that the stiffness effect and geometric nonlinearity of the circular cross-section single-column pylon are obvious. Under the most adverse static loading condition, the displacements of the girder and main pylon of the three-pylon cable-stayed bridge are greater, and the deformation of the middle pylon is larger than one of the side pylons. At the same time, the shear lag effects of ultra-wide steel box girder is obvious. Under the most adverse static loading condition, the stress distribution of the girder section is very uneven and is significantly affected by the cross slope and local load effects. Furthermore, the stress impact effect of the ultra-wide three-pylon cable-stayed bridge is very obvious. Under the conditions of driving and impeded driving, the maximum stress impact coefficients of the top and base plates of steel girder is 0.29, which indicates that more attention should be paid to the damage of deck pavement in the actual operation and avoids the impacts from vehicle bumping effects.