Identification of modal parameters by operational modal analysis of the assessment of bridge rehabilitation

This paper presents a study on the identification of modal parameters by experimental operational modal analysis for the assessment of bridge rehabilitation. Modal parameters of the bridge before and after rehabilitation are estimated. Normal traffic flow over the bridge provided the excitation source. A single 3D accelerometer, located at mid-span of the bridge was used to obtain natural frequencies and damping ratios of the vibration modes. Identification of modal parameters was conducted using four methods including the Peak Picking method (PP), the Least Square Complex Exponential method (LSCE), the Autoregressive method (AR) and the Autoregressive Moving Average method (ARMA). During the study, the concrete deck of the bridge was replaced by orthotropic steel in order to increase its load capacity. The effect of this rehabilitation can be clearly observed through estimated vibration parameters in the stability diagrams.