大跨度双层桁架主梁三分力系数识别

采用风洞试验与计算流体力学（CFD）相结合的方法，对某公铁两用斜拉桥双层桁架主梁在?10°~10°风攻角下的三分力系数进行研究. 利用风洞试验技术测试成桥及施工阶段不同风攻角下主梁的气动力，并识别相应的三分力系数；基于标准k-ε双方程湍流模型建立三维数值计算模型，识别不同风攻角下三分力系数结果，并将其与风洞试验结果对比；结合2种方法研究雷诺数、桥面附属物和公路及铁路交通状况等因素对主梁气动特性的影响. 结果表明低风攻角下雷诺数对主梁气动特性影响较小，可忽略不计，并提出了高风攻角下识别双层桁架三分力系数最低雷诺数的建议值；桥面附属物对主梁阻力系数影响显著，下层桥面附属物有效降低了主梁升力系数；公路车辆对主梁气动系数影响较小，迎风侧列车对主梁阻力系数、升力系数影响显著，背风侧列车对主梁力矩系数影响显著.

Identification of three-component coefficients of double deck truss girder for long-span bridge

The three-component coefficients of double-deck truss girder used in long span rail-road cable-stayed bridge were investigated under wind attack angles from ?10° to 10°, with the combination of wind tunnel test and computational fluid dynamics (CFD) methods. The wind tunnel test was used to test the aerodynamic force of the main beam under different wind attack angles in completion and construction stage, and the three-component coefficients were identified. A three-dimensional numerical calculation model was established based on the standard k-ε two-equation turbulence model to identify the three-component coefficients under different wind attack angles, which were compared with the wind tunnel test results. Combing these two methods, the effects of Reynolds number, bridge attachment and highway and railway traffic conditions on the main girder aerodynamic characteristics were studied. Results show that the Reynolds number has little effect on low wind attack angle, which can be ignored, and the Reynolds number restriction was proposed to identify the three-component coefficient of the double-deck truss under high wind attack angle. The bridge deck attachment has significant influence on the drag coefficient, and the down deck appendant can effectively reduce the main beam lift coefficient. The road vehicles have less influence on the aerodynamic coefficient. The drag and lift coefficients are obviously influenced by the windward train effect, and the moment coefficient are obviously affected by leeward train.