Wavelet energy ratio index for health monitoring of hysteretic dampers

Abstract

Summary This paper presents new contributions to evaluate the damage suffered on a particular type of hysteretic damper called web plastifying damper (WPD) for the passive control of structures subjected to earthquakes. WPDs consist of several I‐section steel segments arranged to form a brace‐type structural element. Energy input by the earthquake is dissipated by the WPD through plastic deformations of the web of the I‐sections. These devices, properly installed in reinforced concrete test models, were tested under successive seismic simulations of increasing magnitude with a shaking table. To assess the damage of the web of the I‐section after each seismic simulation, a new damage index called wavelet energy ratio (WER) was developed; it uses the signals collected by piezoelectric sensors in simple vibration tests. The index is based on wavelet package decomposition and energy calculation of properly chosen wavelet coefficients. It was correlated with a mechanical energy‐based damage index—ID—proposed in past research, which has proven to accurately characterize the level of damage yet requires costly instrumentation to acquire the load–displacement curve needed for its computation. The experiments reported in this paper demonstrate a good correlation between WER and ID indices in a realistic seismic loading scenario. On the basis of this correlation, it is possible to estimate ID indirectly from the WER, which involves much simpler and less expensive instrumentation, easily applicable for in situ continuous monitoring of the dampers.

Application of Vibration Data Mining and Deep Neural Networks in Bridge Damage Identification

“…Some researchers have used wavelet packet component energy [8] and instantaneous frequency after the Hilbert-Huang transform [9] to construct different damage features. Shahsavari et al [10] and Suarez et al [11] chose the coefficients and energy ratio of the wavelet transform for damage identification of structures with good results, respectively.…”

Ultrasonic Pulse-Echo Signal Analysis for Damage Evaluation of Metallic Slit-Plate Hysteretic Dampers

“…Vibration tests have been widely used in the literature [2] to perform modal analysis and to relate the damage to relative variations of modal damping and natural frequencies. In the past, the authors investigated a NDT method consisting of vibration tests [3][4][5][6][7][8] conducted with piezoceramic sensors attached to the hysteretic damper. In this context, the present paper investigates the application of pulse-echo Ultrasonic Tests (UT) as an alternative to the vibration method, to quantitatively assess the level of damage in a "slit plate" damper.…”