Damage detection of highway bridges is a significant part of structural heath monitoring. Conventional accelerometers or strain gauges utilized for damage detection have many shortcomings, especially their monitoring gauge length being too short, which would result in poor damage detection results. Under this circumstance, long-gauge FBG sensors as a novel optical sensor were developed to measure the macro-strain response of the structure. Based on this sensor, many derived damage detection methods were proposed. These methods exhibit various characteristics and have not been systematically compared. As a result, it is difficult to evaluate the state of the art and also leads to confusion for users to select. Therefore, a strict comparative study on three representative methods using long-gauge FBG was carried out. First, these methods’ theoretical backgrounds and formats were reformulated and unified for better comparison. Then, based on validated vehicle–bridge coupling simulation, these methods’ performances were tested through a series of parametric studies including various damage scenarios, vehicle types, speeds, road roughness and noise levels. The precision and reliability of three methods have been thoroughly studied and compared.

Firstly, synchronous field measurements were carried out for the road roughness of the left and right wheels to obtain the roughness profile using a high speed laser roadway testing vehicle. Secondly, programming idea of multi-girder vehicle-bridge coupled vibration analysis module was presented briefly. Finally, a three-axle heavy truck crossing a rigid-frame arch bridge was taken as an example, detailed comparing and analyzing was carried out for the influence on the dynamic responses and spectrum characteristics of the vehicle-bridge system from three excitation cases which include using measured road roughness corresponding respectively to left and right wheels, using measured road roughness of left wheels and right wheels simultaneously. The analysis shows that when the differences in road roughness between left and right wheels are significant, the responses computed with inconsistent excitation is smaller than that with both of the latter two excitation cases, and there are some differences between the vertical contact forces of wheels and the spectrum characteristics of the vehicle-bridge system.

Nowadays, with the rapid development of the traffic infrastructure construction and the growing of the traffic flowing and speed, the vehicle-bridge coupling vibration research has become the focus of the bridge engineering study. The dynamic response of the bridge under the traffic flowing is one of vital parameters for the vehicle-bridge coupling vibration analysis. In this paper, a methodology, employing the radar speed gun, the video recorder, and the dynamic strain tester in combination with manually recording is used to continuously and detailed investigate the traffic loads on the expressway bridge within 24 hours a day. With this approach introduced by this paper, all the critical parameters, such as the vehicle type, speed, traffic lane, the arriving time of the traffic and the bridge-vehicle dynamic interaction are all recorded. In this investigation, firstly the dynamic responses of 8 pieces of beams of the bridge under 5650 individual vehicles driving through the bridge are recorded, secondly statistics analysis are made for the record of each beam, and finally the space-time distribution laws of the dynamic response of the bridge under the traffic flowing are studied extensively. The result of this study could provide helpful theoretic guidance and supporting data for the vehicle-bridge coupling vibration research.

Nowadays, with the rapid development of the traffic infrastructure construction and the growing of the traffic flowing and speed, the vehicle-bridge coupling vibration research has become the focus of the bridge engineering study. The dynamic response of the bridge under the traffic flowing is one of the vital parameters for the vehicle-bridge coupling vibration analysis. In this paper, a methodology, employing the speed radar gun, the video recorder, and the dynamic strain tester in combination with manually recording is used to continuously and detailed investigate the traffic loads on the expressway bridge within 24 hours a day. With this approach introduced by this paper, all the critical parameters, such as the vehicle type, speed, traffic lane, the arriving time of the traffic and the bridge-vehicle dynamic interaction are all recorded. In this investigation, firstly the dynamic responses of 8 pieces of girders of the bridge under 5650 individual vehicles driving through the bridge are recorded, then in conjunction with the investigated traffic flowing samples, in terms of the vehicle type, some detailed statistics study is conducted on the collected records, and finally the space-time distribution laws of the dynamic response of the bridge under the traffic flowing are studied extensively. The result of this study could provide helpful theoretic guidance and supporting data for the vehicle-bridge coupling vibration research.

Field test and analysis were carried out for dynamic responses on a continuous bridge under open traffic. The inspection, testing and analysis for the tested bridge mainly consist of the measurement of pavement roughness and analysis on power spectral density, the testing and analysis on natural vibration characteristics, the observation of traffic loads under open traffic and the corresponding measurements of dynamic displacement and acceleration on bridge. To determine impact factors in terms of measured dynamic displacement responses, low pass Butterworth filter is used for filtering the dynamic part of measured dynamic displacement and the static extreme values are reserved. Finally, the relationship between impact factors and vehicle weight, vehicle speed is studied. It was found that impact factor tends to decrease with increasing vehicle weight, and integrally speaking, the impact factor increases gradually as the vehicle speed is increased within a wide range.