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Structural Engineering and Mechanics   Volume 54, Number 2, April7 2015, pages 257-289
Damage assessment of shear connectors with vibration measurements and power spectral density transmissibility
Jun Li, Hong Hao, Yong Xia and Hong-ping Zhu

Abstract     [Buy Article]
    Shear connectors are generally used to link the slab and girders together in slab-on-girder bridge structures. Damage of shear connectors in such structures will result in shear slippage between the slab and girders, which significantly reduces the load-carrying capacity of the bridge. Because shear connectors are buried inside the structure, routine visual inspection is not able to detect conditions of shear connectors. A few methods have been proposed in the literature to detect the condition of shear connectors based on vibration measurements. This paper proposes a different dynamic condition assessment approach to identify the damage of shear connectors in slab-on-girder bridge structures based on power spectral density transmissibility (PSDT). PSDT formulates the relationship between the auto-spectral densities of two responses in the frequency domain. It can be used to identify shear connector conditions with or without reference data of the undamaged structure (or the baseline). Measured impact force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at sensor locations by experimental modal analysis. PSDT from the slab response to the girder response is derived with the obtained frequency response functions. PSDT vectors in the undamaged and damaged states can be compared to identify the damage of shear connectors. When the baseline is not available, as in most practical cases, PSDT vectors from the measured response at a reference sensor to those of the slab and girder in the damaged state can be used to detect the damage of shear connectors. Numerical and experimental studies on a concrete slab supported by two steel girders are conducted to investigate the accuracy and efficiency of the proposed approach. Identification results demonstrate that damages of shear connectors are identified accurately and efficiently with and without the baseline. The proposed method is also used to evaluate the conditions of shear connectors in a real composite bridge with in-field testing data.
Key Words
    condition assessment; shear connectors; power spectral density transmissibility; structural monitoring; slab-on-girder bridge; frequency response function
Jun Li, Hong Hao: Department of Civil Engineering, School of Civil and Mechanical Engineering, Curtin University, Bentley, WA 6102, Australia
Yong Xia: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People\'s Republic of China
Hong-ping Zhu: School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan, Hubei, People\'s Republic of China

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