基于汽车-桥梁非线性耦合系统的曲线桥损伤识别研究

When a high speed heavy vehicle passing through a curved bridge, the vehicle has vertical dynamic impact to the bridge, and also due to the effect of eccentricity and centrifugal force, the curved bridge takes place torsion dynamic response. All of these are directly impact the curved bridge health and lifetime. Because the heavy vehicle body is long and the roll center is high, the heavy vehicle is easy to drift or rollover when braking and passing through the curved bridge. The tire stiffness presents obvious nonlinear. Curved bridge is geometric nonlinear, and bridge reinforced concrete is material nonlinear. Therefore, when the heavy vehicle passes through the curved bridge, the vehicle and the curved bridge is a coupling nonlinear system. In this project, the vehicle-curved bridge nonlinear coupling system model will be established, and the vehicle and the curved bridge are coupled with three-directional nonlinear tire forces. The curved bridge displacement responses will be calculated by this model. The sensibility of the curved bridge displacement responses to the curved bridge damage will be researched, and then the damage identification index will be created. The nonlinear Support Vector Machine will be utilized to establish the curved bridge damage location identification model and the damage degree identification model. These models' anti-noise capacity and generalization will be analyzed. At last, a curved bridge laboratory model will be built to validate the theoretical results. The research results will provide a new efficient and stronger operability nonlinear damage identification method for the highway curved bridge damage identification and have important practical significance to guarantee the curved bridge security operation.

汽车通过曲线桥时，不仅对桥梁产生竖向动力冲击作用，还会由于偏心和离心力的作用，使桥梁产生扭转动力响应，直接影响桥梁的健康状态和使用寿命。重型汽车车身长、侧倾中心高，转弯制动时易发生甩尾、侧翻等失稳现象，此时其轮胎刚度呈现明显的非线性，曲线桥具有几何非线性，桥梁的钢筋混凝土具有材料非线性，因此，重型汽车通过曲线桥时，汽车与曲线桥是一个相互耦合的非线性系统。本项目拟建立汽车-曲线桥非线性耦合系统，汽车与曲线桥通过三向非线性轮胎力耦合。计算汽车通过曲线桥时桥梁的位移响应，研究桥梁位移响应对桥梁损伤的敏感性，从而创建损伤识别指标。采用非线性支持向量机建立曲线桥损伤位置识别模型和损伤程度识别模型，分析损伤识别模型的抗噪能力和泛化性，并建立曲线桥实验室模型，对理论计算结果进行实验验证。研究成果将为公路曲线桥提供一种新的实时高效、可操作性更强的非线性损伤识别方法，对保障曲线桥安全运营具有重要的现实意义。

当重型汽车高速通过曲线桥时，由于其惯性大、车身长、侧倾中心高，会产生很大的离心力，不仅对曲线桥产生竖向动力作用，还会由于偏心和离心力对曲线桥产生扭转动力作用，使曲线桥的受力状态直线桥复制的多，直接影响其健康状态和使用寿命。因此，研究汽车与曲线桥非线性耦合的系统及损伤识别，对保证曲线桥的安全运营、控制车辆荷载和通行速度等均具有重要的工程应用价值。.本项目建立了汽车-曲线桥有限元模型及重型汽车-曲线桥三向耦合动力学模型，分析了几何非线性和材料非线性对曲线桥动力响应的影响情况，探索了重型汽车通过曲线桥时的非线性动力学问题；研究了曲线桥损伤识别的敏感指标；设计加工制作车-曲线桥耦合系统实验室模型，并进行实验室研究；最后基于上述损伤识别指标和实验结果，进行了曲线桥的损伤识别研究。.重要结果及关键数据：.（1）采用ANSYS建立了车-曲线桥有限元模型、三轴九自由度的汽车模型并与曲线桥耦合。.（2）考虑几何非线性的曲线桥的动挠度振幅比不考虑几何非线性时小，冲击系数也相应减小。考虑材料非线性后，曲线桥跨中竖向位移、横向位移及扭转角的峰值均比不考虑材料非线性的计算结果偏大。.（3）建立了车-曲线桥耦合系统的实验室模型，及相应的有限元计算模型。.（4）频率对连续曲线梁边跨的损伤不敏感，对中跨的损伤较敏感。曲线梁横截面上外侧点的挠度变化率比内侧点的挠度变化率对损伤更敏感。.（5）基于挠度变化率的损伤位置识别模型和损伤程度识别模型均具有很强的泛化性和抗噪能力。.基于汽车-曲线桥非线性耦合系统的曲线桥损伤识别研究涉及车辆动力学、桥梁动力学、信息处理、数据挖掘，属于机械、土木、力学、信息等多学科交叉的前沿问题，可以丰富研究内容，揭示桥梁结构发生损伤时汽车-曲线桥非线性耦合系统的动力学行为，具有重要的科学意义。