Damage detection of shear connectors under moving loads with relative displacement measurements

•A new sensor is used to measure the relative displacement for health monitoring.•Measured relative displacements are used for damage detection of shear connectors.•Damage detection is conducted under moving loads with CWT and HHT.•Damage detection is performed for composite bridges under ambient vibrations.•Numerical and experimental investigations are conducted.

This paper investigates the use of relative displacement measurements from the newly developed relative displacement sensors to identify the damage of shear connectors in composite bridges. Continuous Wavelet Transform and Hilbert–Huang Transform are applied to analyze the measured dynamic responses and to identify the damage of shear connectors in the composite bridge model under moving loads. Comparative studies by using the relative displacement, acceleration and displacement measurements respectively for the damage detection are conducted. A comparative study of using relative displacements and acceleration responses of the bridge under ambient excitations to monitor the shear connector conditions is also conducted. Numerical and experimental studies demonstrate that both relative displacement and acceleration measurements can identify the location and the instant of damage occurrence in shear connectors when the bridge is under moving loads. The results demonstrate that relative displacement is a better response quantity for structural health monitoring of composite bridges.