OPERATIONAL DAMAGE DETECTION TECHNIQUE FOR URBAN HIGHWAY BRIDGE USING DISTRIBUTED STRAIN

The aim of this paper is to develop an alternative technique to classical displacement or strain mode shape based structural damage detection methods corresponding to distributed strain measurements, which served for Urban Highway Bridges (UHB). UHBs in operating are mainly subjected to non-stationary traffic loadings, which are not easily to resonant or disturbed by harmonic components caused by moving vehicles, consequently conventional modal parameters based damage detection methods may not meet our expectation for the real application. In this paper, a new damage detection technique using operational distributed strain shape (ODSS) is proposed without any extraction of strain modal parameters. First, the expression of ODSS in frequency domain by distributed strain transmissibility measurements is constructed with the analytical derivation. Then, a simulated UHB finite element model is created for the clarification of how to make use of ODSSs for detecting damages occurred in the girder of the UHB. Due to the ODSS is related to external forces, different loading cases will result in inconsistent ODSSs even when those at the same frequency. Hence statistical damage index (SDI) at and around sensitive frequencies are used to improve the robustness of the results. In sum, the proposed strategy is expected to be one of the most practical tools in nondestructive testing (NDT) field due to easy implementation and sensitive to broad area damages, and it reveals promising in exploiting distributed sensing techniques for structural damage detection to UHB.