An integrated vibration-image procedure for damage identification in steel trusses

The paper deals with structural damage identification in steel trusses. Classical procedure based on dynamic measurements able to detect flexibility changes are complemented with data predicting cracks and their evaluating by image processing. The procedure proposes first a damage index, the Stiffness Reduction Factor (SRF), evaluated on the basis of the error between the predictive truss model and the experimental modal model. Then, a nonlinear FEM model is used to determine fatigue cracks in the truss nodes which are compared with the observed ones determined by image processing. A real case study, the Quisi bridge located in Spain, is used to show the potentiality of the procedure.