风荷载对车桥耦合振动及行车舒适性影响

Influence of Wind Load on Vehicle-bridge Coupling Vibration and Riding Comfort

为保证大跨度桥梁结构的安全性及桥上运行车辆的稳定性和舒适性,建立了风-车-桥耦合分析模型对系统的振动响应进行研究。通过三角级数法模拟了不同等级下的桥面不平整度,以探究车辆振动激励源的影响规律。采用快速谱分析法生成了桥梁不同节点处的横向和竖向脉动风速时程。建立了双轴四轮13自由度的汽车模型。以跨度为(180+216+180)m公铁两用的九江长江大桥为工程背景,建立桥梁有限元模型计算其自振频率及振型。采用模态综合法推导了风-车-桥系统动力平衡微分方程,采用Newmark-β积分对具有时变特性的动力平衡微分方程进行求解,并编写相应计算程序,研究不同工况下车辆及桥梁的振动响应。并根据ISO2631—1997标准计算车体的计权加速度均方根,对行车舒适性进行评价。针对不同风速、不同桥面等级、不同行驶速度等条件下,车辆匀速行驶通过桥梁时车辆的动力响应和行车舒适性进行评价,并计算了风及车辆对桥梁的动力加载作用。结果表明:车辆的动力响应会随着风速的增大、桥面状况的变差和车辆行驶速度的增加而增大,行车舒适性也相应变差;风速的增大会使桥梁的竖向位移减小,而竖向加速度和横向振动响应会显著增大。大跨度桥梁对风及车辆的动力加载均比较敏感,在桥梁的设计和运营阶段均应给予足够的重视。

In order to ensure the safety of the long-span bridge structure,and the stability and comfort of vehicle running on bridge,a coupling vibration analysis model for wind-vehicle-bridge is established.The roughness of the bridge surface with different grades is simulated by using the trigonometric series method to study the excitation source of the vehicle.The vertical and lateral wind load is generated by using the fast spectral analysis method.A dual-axle,four-wheel,13-degree-freedom car model is established.The Jiujiang Yangtze River bridge with a span of(180+216+180)m is selected as the engineering background.A finite element model for the bridge is established for natural frequency and vibration mode calculation.The mode superposition method is used to establish the differential equations of vehicle-bridge coupled vibration balance,and Newmark-βintegral iteration is adopted to solve the time varying equations.The specification ISO2631—1997 is used to calculate the vibration response of the vehicle body,and the total weighted acceleration root-mean-square of vehicle is calculated.The acceleration time history is performed with spectrum analysis to evaluate the driving comfort.The dynamic responses and riding comfort are analyzed when vehicles passing the bridge under different wind loads,driving speeds and bridge roughness,and the dynamic loads of wind and vehicles on the bridge are calculated as well.The result shows that the dynamic responses of the vehicles increase with the increase of wind speed,the deterioration of bridge surface roughness and the raise of vehicle speed.The riding comfort will deteriorate accordingly.The increase of the wind velocity reduces the maximum vertical displacements of the bridge,while the vertical acceleration and lateral vibrations increase significantly.Long-span bridges are sensitive to wind and vehicle dynamic loading,therefore,sufficient attention should be paid on the design and operation stages of bridges to ensure the safety of both bridge structure and running vehicles.