Monitoring a sudden crack of beam-like bridge during earthquake excitation

Abstract

This paper presents a wavelet spectrum technique for monitoring a sudden crack of a beam-like bridge structure during earthquake excitation. When there is a sudden crack caused by earthquake excitation the stiffness of the structure is changed leading to a sudden change in natural frequencies during vibration. It is difficult to monitor this sudden change in the frequency using conventional approaches such as Fourier transform because in Fourier transform the time information is lost so that it is impossible to analyse short time events. To overcome this disadvantage, wavelet spectrum, a time-frequency analysis, is used for monitoring a sudden change in frequency duringearthquake excitation for crack detection. In this study, a model of 3D crack is applied. The derivation of the stiffness matrix of a 3D cracked beam element with rectangular section adopted from fracture mechanics is presented. Numerical results showed that the sudden occurrence of the crack during earthquake excitation can be detected by the sudden change in frequency using wavelet power spectrum. When the crack depth increases, the instantaneous frequency (IF) of the structure is decreased.

Rapid post-earthquake damage assessment of ageing reinforced concrete bridge piers using time-frequency analysis

“…Recently, several researchers introduced time-frequency representatives including the wavelet transform (WT) (Adeli & Jiang, 2006;Cruz & Salgado, 2009;Giurgiutiu & Yu, 2003;Guo & Kareem, 2016a;Khoa, 2013;Melhem & Kim, 2003;Nagarajaiah & Basu, 2009;Qiao et al, 2012;Spanos et al, 2007;Spanos & Failla, 2005;Staszewski & Robertson, 2007;Tang et al, 2010;Wong & Chen, 2001), the Fourier transform (FT), the short-time Fourier transform (STFT) (El Shafie et al, 2012;Giurgiutiu & Yu, 2003;Guo & Kareem, 2016a;Melhem & Kim, 2003;Nagarajaiah & Basu, 2009), the Hilbert transform (HT) (Feldman, 2014;Kunwar et al, 2013;Loutridis, 2004;Pines & Salvino, 2006;Roy et al, 2019;Salvino et al, 2003;Si et al, 2016) and the Wigner-Ville distribution (WVD) (Berinde et al, 2006;Bradford et al, 2006;G. Chen et al, 2013;Claasen & Mecklenbräuker, 1980;Guo & Kareem, 2016b;Martin & Flandrin, 1985;Tang et al, 2010;Wu & Chiang, 2009) as non-parametric system identification strategies (Salvino et al, 2003).…”

“…Chen et al, 2013;Claasen & Mecklenbräuker, 1980;Guo & Kareem, 2016b;Martin & Flandrin, 1985;Tang et al, 2010;Wu & Chiang, 2009) as non-parametric system identification strategies (Salvino et al, 2003). Khoa (2013) demonstrated the robustness of WT when the noise-to-signal ratio is under 15%. Wong and Chen (2001) found the performance of WT is acceptable for structures with low non-linearity.…”

Exact receptance function and receptance curvature of a clamped-clamped continuous cracked beam

“…Thalapil and Maiti [11] revealed the change in natural frequencies caused by longitudinal cracks for crack detection. Khoa [12] proposed a method for monitoring a sudden crack of a beam-like bridge appeared during earthquake excitation based on the instantaneous frequency extracted from wavelet power spectrum. Some authors presented methods to calculate and apply the mode shape of cracked structures for crack detection purposes.…”