Damage Detection and Condition Monitoring of Pre-stressed Concrete Bridges by using Vibration-based Health Monitoring Techniques

Damage detection plays a vital role in bridges as the structural performance of the bridges decreases progressively throughout their service life due to many deterioration processes. Although damage detection is performed mainly through periodic visual inspection, due to its immense drawbacks, researchers have focused increasing attention to the potential of using vibration-based structural health monitoring (V-SHM) techniques to detect damages and monitoring conditions of the structures. The fundamental theory of the V-SHM is that structural damages will change mass, stiffness and damping properties of structures leading to detectable changes in their dynamic characteristics such as natural frequencies, mode shapes and modal damping ratios. The applicability of V-SHM techniques to detect the existence of damage in pre-stressed concrete bridges by experimentally identifying their dynamic characteristics is reported in this study. Eigen-system Realization Algorithm (ERA) was used for experimental modal analysis of the bridges by using the free vibration records extracted from field vibration measurements. Numerical modal analysis for the bridges was performed using finite element models of the bridges to obtain the dynamic characteristics of the intact structures. The identified dynamic characteristics from both experimental and numerical approaches were used in obtaining an indication of the possible level of existence of damages in studied pre-stressed concrete bridges. Three global damage identification (DI) criterions are defined and evaluated to further corroborate that these bridges have not undergone appreciable damages, as the evaluated DI criterions are within acceptable tolerances for no damage state, accommodating noisy data.