山区峡谷非均匀风场下大跨度斜拉桥静风稳定性分析

为研究山区峡谷地形下非均匀风场对大跨度桥梁静风稳定性的影响，以一座跨越典型山区峡谷地形的大跨度斜拉桥为工程背景，首先，采用计算流体动力学（CFD）软件Fluent对桥址区地形的风场特性进行分析，计算出沿主梁方向的非均匀风速和非均匀风攻角分布；然后，采用ANSYS APDL技术实现能考虑非均匀风速和非均匀风攻角下大桥静风稳定性的非线性分析方法。在此基础上，综合考察非均匀风攻角分布、非均匀风速分布、非均匀风速非均匀风攻角分布等风场条件对大桥静风稳定性的影响，分析各工况下主梁的静风变形与跨中处拉索刚度变化。研究结果表明：与均匀风场条件下的静风响应不同，非均匀风攻角或非均匀风速下主梁静风响应最大值点位于风荷载峰值点与跨中之间，在针对非均匀风场下大桥的静风稳定性分析时，应更注重静风响应最大值点而不是跨中处；非均匀风攻角下大桥的静风失稳临界风速要远低于均匀风攻角的静风失稳临界风速，且其静风稳定性能主要受最大风攻角而不是主跨部分非均匀风攻角的平均值来控制；非均匀风速下大桥的静风失稳临界风速主要由主跨部分的风速平均值和最大值共同影响；主梁的竖向位移和扭转角形状主要由风攻角因素来控制，而横向位移的变化规律相对较独立，其形状基本上以跨中线对称，且其值主要由风速因素来决定。

Aerostatic Stability of Long-span Cable-stayed Bridge Under Inhomogeneous Wind Fields Induced by Mountain-gorge Terrain

To study the effects of inhomogeneous wind fields induced by the mountain-gorge terrain on the aerostatic stability of long-span bridges, a long-span cable-stayed bridge straddling a typical mountain-gorge terrain was considered as an engineering background. First, the wind characteristics at the bridge site were analyzed using the computational fluid dynamics (CFD) software FLUENT, and the inhomogeneous wind speeds and inhomogeneous wind attack angles along the bridge main beam were calculated. Then, a nonlinear methodology that can analyze the aerostatic stability of long-span bridges under inhomogeneous wind speeds and inhomogeneous wind attack angles was implemented by adopting the ANSYS APDL technology. Based on this, the effects of inhomogeneous wind attack angles, inhomogeneous wind speeds, and both together on the aerostatic stability of a long-span cable-stayed bridge were comprehensively investigated. Also, the aerostatic deformation of the bridge main beam and the stiffness variation of the cable near the mid-span point were analyzed. The results show that the maximum value's position of the aerostatic response under inhomogeneous wind speeds or inhomogeneous wind attack angles is located between the peak position of wind loads and the mid-span point, which is different from the behavior under homogeneous wind fields. Therefore, the maximum value's position of the aerostatic response is more important than the mid-span point when analyzing the aerostatic stability of long-span bridges under inhomogeneous wind fields. The critical wind speed of the aerostatic instability under inhomogeneous wind attack angles is considerably smaller than that under inhomogeneous wind speeds, and the performance of the aerostatic stability under inhomogeneous wind attack angles depends mainly on the maximum wind attack angle rather than the average value of the inhomogeneous wind attack angles along the main beam. The critical wind speed of the aerostatic instability under inhomogeneous wind speeds is influenced both by the average wind speed and maximum wind speed along the main span. The shapes of the vertical displacements and torsion angles are mainly dominated by the wind attack angles. However, the lateral displacements are relatively independent, with shapes that are generally symmetric about the mid-span line, and the values are mainly determined by the wind speeds.