Multi-level damage identification in operational condition

Aim of this paper is the description and the comparison of two Structural Health Monitoring (SHM) techniques to identify a structural damage of a tower crane. First technique considers the natural frequencies and the mode shapes. Consequently, the damage is localized and quantified exploiting well-known techniques, implemented in a Multi-Level Damage Identification Platform (MuDI). The second approach considers the displacement of some points of the crane due to the excitation of a running load. In this case, Continuous Wavelet Transform (CWT) is performed and, by analyzing the CWT coefficients, only the damage position is identified. This second approach requires few sensors and optimizes cost that is a relevant parameter in operational conditions. The obtained results of these two techniques are compared, together with their efficiency.