DAMAGE ASSESSMENT OF MULTIPLE CRACKED BEAMS - NUMERICAL RESULTS AND EXPERIMENTAL VALIDATION

A method is presented in this paper which uses the modal parameters of the lower modes for the non-destructive detection and sizing of crack s in beams. Using a finite element model of the structure to calculate the dynamic behaviour analytically, it is possible to formulate the i nverse problem in optimization terms and then to utilize a solution pr ocedure employing genetic algorithms. The damage assessment technique has been applied both to simulated and to experimental data related to cantilevered steel beams, each one with a different damage scenario; i.e., the position and depth of the cracks. It is demonstrated that th is method can detect the presence of damage and can estimate both the crack positions and sizes with satisfactory precision. The problems re lated to the tuning of the genetic search and to the virgin state cali bration of the model are also discussed. (C) 1997 Academic Press Limit ed.