Experimental analysis for identification of bridges structural damage using Operational Modal Analysis based methods

Recent structural collapses of bridges and damaging occurred on deck and dampers of suspension bridges, are driving the development of monitoring techniques for the structural integrity assessment of primary lifelines. Structural Health Monitoring combines a variety of methods for observed dynamic systems response detection of different structural systems. Among others techniques, Operational Modal Analysis, combined with efficient techniques for modal parameters identification, seems well suited for Vibration-Based Damage Detection (VBDD) of bridges under operating traffic loads. This paper addresses the issue, of the effectiveness of VBDD algorithms based on strain energy or modal flexibility matrices for the damage detection of bridge structures under operational loads. A reduced scale model of a three-span bridge was developed to evaluate the interaction effects between moving loads and structure and to investigate the algorithms sensitivity to different input levels and the damage prediction for different sensors density and damage size.