DAMAGE DETECTION OF SPACE FRAME STRUCTURES WITH L-SHAPED BEAMS AND BOLTED JOINTS USING CHANGES IN NATURAL FREQUENCIES

It is difficult to use conventional non-destructive testing methods to detect damage, such as loosening of bolted connec-tions, in a space frame structure due to the complexity of the structure and the nature of the possible damage. A vibration-based method that uses changes in the natural frequencies of a structure to detect the locations and extent of damage in it has the advantage of being able to detect various types of dam-age in the structure, including loosening of bolted connections. Since the vibration-based method is model-based, applying it to a space frame structure with L-shaped beams and bolted joints will face challenges ranging from the development of an accu-rate dynamic model of the structure to that of a robust damage detection algorithm for a severely under-determined, nonlinear least-square problem under the effects of relatively large mod