Scour diagnosis index based on cross-correlation analysis of bridge dynamic response under vehicle braking

Abstract

Several innovative scour diagnostic indexes are proposed based on the cross-correlation analysis for bridge dynamic response excited by vehicle braking. Firstly, a vehicle-bridge coupled vibration model considering vehicle braking is established and its accuracy is verified by a field loading test. Secondly, the fixed shape characteristic of cross-correlation function amplitude vector of the braking-induced dynamic response is theoretically deduced and verified numerically with a continuous girder bridge example considering various test parameters, which is the basic for scour diagnosis. Further, two scour diagnostic indexes are proposed, one is the cross-correlation function amplitude change rate vector, which is used to identify the scour location with a threshold of 2%, and the other is the transversal cross-correlation function amplitude change rate vector, which is used to identify the scour uniformity. The good applicability and accuracy of proposed indexes for different scour states is verified by numerical simulation for above bridge example. The proposed diagnostic indexes are very sensitive to foundation scour and have strong error tolerance for test parameters. The dynamic response required for scour diagnosis can be obtained with regular bridge loading test.

A Review of Vibration-Based Scour Diagnosis Methods for Bridge Foundation

“…For example, based on the fast and flexible braking function of the vehicles, the braking force was used to excite the bridge longitudinal vibration, and its effect is better than that of the normal traffic load [72]. Several potential methods for rapid scour diagnosis have been proposed and validated via numerical simulation [73,74], and laboratory and field tests are also being carried out. In addition, moving impact vibration test technique, with the advantages of both forced excitation and moving vehicle excitation, may also be used to develop innovative, reliable and rapid scour diagnosis schemes.…”

“…Focusing on this problem, Li et al [72] studied the effect of vehicle braking on bridges, and found that braking action stimulated significant structural longitudinal vibration sensitive to scour. Further, scour diagnosis methods based on braking excitation were proposed and validated via numerical simulation [73,74]. This research developed a new application scenario for moving vehicle excitation.…”

“…A vehicle-bridge coupled vibration model considering vehicle braking was established [73]. The braking force coefficient (the ratio of braking force to vehicle weight) was assumed to be a ramp function.…”

“…The proposed method can be used for Recently, several scour diagnosis methods have been proposed based on vehicle brake excitation and verified via numerical simulation. Zhang et al [73] applied dynamic response cross−correlation index to conduct scour diagnosis. The longitudinal acceleration response of the bridge excited by vehicle braking was extracted to calculate the crosscorrelation index, CorV.…”

“…The influence of scour on the bridge dynamic performance varies with the type of foundation, leading to different scour indicators. For shallow foundations, scour removes the soil around the foundation, weakening the horizontal constraint of the soil for the foundation and the stress level of the basement soil, resulting in a decrease in the horizontal and vertical stiffness of the substructure [42,72,73]. Therefore, scour indicators can be constructed using bridge horizontal and vertical modes or vibration.…”