Study on Laboratory Tests of Indirect Bridge Frequencies Identification Based on Vibration Responses of a Passing Vehicle
To demonstrate the ability of utilizing vehicle vibration signals to identify multiple bridge fre-quencies,a scaled vehicle-bridge interaction(VBI)laboratory test was constructed to scan bridge frequencies using a two-axle test vehicle under the impact of various factors.Firstly,descriptions were presented for the model beam and test vehicle in the scaled VBI lab test.Then,vibration signals acquired from sensors mounted on the model beam,bottom steel plate of the test vehicle,and the top steel plate of the test vehicle were compared to check their effectiveness in identifying bridge frequencies.Finally,the impact of suspension stiffness,vehicle mass,road surface roughness,and traffic-induced excitation on the indirect identification of bridge frequencies was investi-gated.The results show that the vibration sensor on the bottom plate of the test vehicle successfully identifies the first three vertical frequencies and the first two torsional frequencies of the bridge,which closely matched the spec-trum obtained from a sensor installed on the bridge.This finding indicates that the vibration of the bottom plate of the test vehicle is not significantly affected by the vehicle suspension and additional mass.However,the vibration sensor on the top plate of the test vehicle could accurately identify the first vertical vibration frequency of the bridge but could struggle to identify higher-order bridge frequencies due to interference from the vehicle frequency itself.Various factors primarily influenced the identification performance of bridge frequencies by the sensor on the top plate of the test vehicle,while their impact on the sensor on the bottom plate of the test vehicle was minimal,thus verifying the superiority of the designed test vehicle for indirectly scanning bridge frequencies.
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