侧风下桥上超车车辆的动力响应及行车安全性研究

DYNAMIC RESPONSES AND DRIVING SAFETY OF VEHICLES OVERTAKING ON BRIDGE UNDER CROSSWINDS

  • 摘要: 大跨度桥梁上行驶的车辆极易遭受侧风的影响。车辆在桥上超车时,因临近车辆之间的气动干扰易引发车辆气动荷载的突变,这将严重影响车辆的行车安全性。通过节段模型风洞试验,以大型集装箱挂车和厢式货车为例,测试了两种车辆布局形式下车辆在超车过程中的气动荷载特性。考虑瞬态气动荷载突变效应对车辆动力响应的影响,建立了较为完善的风-车-桥耦合振动分析框架。分析了不同车辆布局、风速和车速等因素对超车车辆动力响应特性的影响,采用无量纲荷载转移率(LTR)和侧滑安全因子(SSF)重点考察了侧风下超车车辆的行车安全性问题。研究结果表明:超车车辆之间气动干扰使得背风侧车辆气动荷载在超车过程中出现了大幅的剧烈波动;随着风速和车速的提高,车辆的LTR和SSF逐渐呈现出非线性的增长趋势。车辆的行车安全性与车型密切相关,厢式货车更容易发生侧翻事故,而大拖挂车更容易发生侧滑事故。

     

    Abstract: Vehicles traveling on long-span bridges are highly susceptible to crosswinds. As vehicles overtaking on a bridge deck, the aerodynamic interferences between the adjacent overtaking vehicles may give rise to a sudden change of aerodynamic loads acting on the vehicles, which could seriously affect the driving safety of vehicles. Taking a large container trailer and a van as examples, the aerodynamic characteristics of vehicles during the overtaking process are available by means of segment wind tunnel tests under tow different vehicle layouts. Considering the influence of the transient abrupt effect of the aerodynamic loads on the dynamic responses of vehicles, a relatively complete wind-vehicle-bridge coupling vibration analysis framework is established. The dynamic response characteristics of overtaking vehicles are investigated under various affected factors such as vehicle layout, wind velocity and vehicle speed. It focuses on the driving safety issues for the overtaking vehicles under crosswind, which are evaluated by the introduced safety indicators including dimensionless load transfer rate (LTR) and sideslip safety factor (SSF). The results show that the aerodynamic interference between the overtaking vehicles causes a large fluctuation of the aerodynamic loads for leeward vehicle during the overtaking process. With the increase of wind speed and vehicle speed, the LTR and SSF of vehicles gradually show a non-linear growth trend. The driving safety depends on the vehicle type. Vans are more likely to suffer rollover accidents, while large trailers are easier to suffer sideslip accidents.

     

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