基于车桥耦合振动的RC系杆拱桥加固效果评价

为了对采用吊拉主动加固方法的钢筋混凝土系杆拱桥进行基于车桥耦合振动分析的加固效果评价，首先，利用ANSYS软件建立空间梁、板和杆单元的桥梁结构有限元梁格模型，并选取三轴9自由度的车辆模型及路面不平度等级B分别模拟实际车辆及桥面状态，将梁格模型调入BDANS软件，通过数值模拟车、桥动力响应，计算得到桥梁动位移、加速度响应，研究加固前后桥梁控制截面所受到的动力冲击作用；然后，分析桥梁加固前后不同位置加速度响应的频谱特征；最后，对依托工程动力特征、动态响应及车桥耦合作用的实测值与理论值进行比较分析。结果表明：通过该方法加固后结构的竖向自振频率较加固前均有提升，但提升幅度较小；加固前后结构不同位置的动力响应随车速增加呈逐渐增大的趋势，且车速在60～80 km·h^-1时，加固后结构跨中截面的动力响应降幅最大；加固后结构控制截面的加速度均方根值小于加固前，根据其变化幅值建议车辆通过加固后桥梁结构的速度为60 km·h^-1，以保证行人过桥时的体感舒适度、通行效率及行车安全；通过理论值与实测值的对比分析，验证了基于车桥耦合振动分析方法对桥梁结构加固后行车性能评价的有效性。

Evaluation of Reinforcement Effect of an RC Tied Arch Bridge Based on Vehicle Bridge Coupled Vibration

To evaluate the reinforcement effect on the bridge-coupled vibration analysis of a reinforced concrete (RC) tied arch bridge adopting the active reinforcement method, ANSYS software was used to establish the space beam, plate, and bar element of the bridge beam finite element model first, and then a three-axis nine degrees of freedom (9-DOF) vehicle model and a road surface roughness of level B were selected to simulate the actual vehicle and bridge deck status. Subsequently, the beam model was transferred to BDANS software to calculate bridge dynamic displacement, acceleration response by numerical simulation, and vehicle and bridge dynamic responses to study the dynamic impact on the modeled bridge section before and after reinforcement. Simultaneously, the spectral characteristics of acceleration response at different positions before and after bridge reinforcement were analyzed. Finally, the measured value and the theoretical value based on the engineering dynamic characteristics, dynamic response, and axle-axle coupling effect were compared and analyzed. The results show that the vertical natural frequency of the structure after reinforcement is higher than that before reinforcement; however, the improvement is low. The dynamic response at different positions of the structure before and after reinforcement tends to increase with increasing vehicle speed, and when the speed is in the range of 60 km·h^-1 to 80 km· h^-1, the dynamic response of the mid-section of the structure decreases the most after reinforcement and the root mean square acceleration of the structural control section after reinforcement is less than that before reinforcement. According to the magnitude of the change, it is suggested that the speed of the vehicle passing through the bridge structure should be 60 km·h^-1 or less to ensure the comfort level, traffic efficiency, and traffic safety of pedestrians crossing the bridge. Through comparison of the theoretical and measured values, the validity of this method based on the analysis of bridge-coupled vibration to model the in-service performance of the bridge structure is verified.