Abstract
Damage detection and structural health monitoring have always been of great importance to civil engineers and researchers. Vibration-based damage detection has several advantages compared to traditional methods of non-destructive evaluation, such as ground penetrating radar (GPR) or ultrasonic testing, since they give a global response and are feasible for large structures. Damage detection requires a comparison between two systems states, the baseline or “healthy state”, i.e., the initial modal parameters, and the damaged state. In this study, system identification (SI) was carried out on a pedestrian bridge by measuring the dynamic response using six low-cost triaxial accelerometers. These low-cost accelerometers use a micro-electro-mechanical system (MEMS), which is cheaper compared to a piezoelectric sensor. The frequency domain decomposition algorithm, which is an output-only method of modal analysis, was used to obtain the modal properties, i.e., natural frequencies and mode shapes. Three mode shapes and frequencies were found out using system identification and were compared with the finite element model (FEM) of the bridge, developed using the commercial finite element software, Abaqus. A good comparison was found between the FEM and SI results. The frequency difference was nearly 10%, and the modal assurance criterion (MAC) of experimental and analytical mode shapes was greater than 0.80, which proved to be a good comparison despite the small number of accelerometers available and the simplifications and idealizations in FEM.
Highlights
Engineers and researchers have always been concerned with the damage identification and health monitoring of structures [1,2]
Vibration-based damage detection (VBDD) conquers the aforementioned problems by giving a global response, being suitable for large structures, and having the ability to carry out continuous health monitoring
System Identification (SI) was carried out on a 9.8 meter-long, double-tee beam used as a Pedestrian Bridge at the National University of Science and Technology (NUST) in Islamabad, Pakistan for the purposes of structural health monitoring
Summary
Engineers and researchers have always been concerned with the damage identification and health monitoring of structures [1,2]. Structural health monitoring has been defined in the literature as “the use of in-situ, non-destructive sensing and analysis of system characteristics, including structural response, for the purpose of detecting changes, which may indicate damage or degradation” [4]. Vibration-based damage detection (VBDD) conquers the aforementioned problems by giving a global response, being suitable for large structures, and having the ability to carry out continuous health monitoring. The main theoretical background behind vibration-based damage detection is that the properties of a structure, i.e., mass, stiffness, and damping, are affected by induced damages These damages change the observable modal parameters, i.e., natural frequencies and mode shapes [6]. System Identification (SI) was carried out on a 9.8 meter-long, double-tee beam used as a Pedestrian Bridge at the National University of Science and Technology (NUST) in Islamabad, Pakistan for the purposes of structural health monitoring.
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