A double-pass method for bridge assessment considering surface roughness using normalized contact point responses

Abstract

This paper proposes a method to identify bridge modal parameters and detect possible damage location(s) using an instrumented vehicle based on vehicle-bridge interaction considering surface roughness. Existing vehicle-response-based bridge damage detection methods usually ignore surface roughness as it will contaminate the vehicle response data. The double-pass method is built upon the equations of motion of the bridge and vehicle. Then the normalized contact point response is obtained from the reponses of the vehicle passing on the bridge twice with extra mass added during the second pass. The normalized contact point response is relatively immune to the additional excitations due to surface roughness. The frequencies and mode shapes of the bridge can be further extracted from the normalized contact point acceleration with spectral analysis and Hilbert transform. The damage can be located accordingly using wavelet transform and coordinate modal assurance criterion. The effectiveness of the proposed method is verified by numerical simulation. The result shows that the proposed method can extract bridge frequencies and mode shapes, and identify single and multiple damage scenarios accurately in the presence of surface roughness of different classes.