Estimation and Warning of Fatigue Damage of FRP Stay Cables Based on Acoustic Emission Techniques and Fractal Theory

Abstract

A damage assessment and warning method for stay cables based on the acoustic emission (AE) technique and fractal theory was developed. First, the AE signal features of Higuchi's fractal dimension (FD) were analyzed at various scales. The analytical results indicated that the FD was associated with the frequency response. Meanwhile, it was found that the curve length of the original signal reflected the fluctuation of the AE signal in the time domain. Both the FD and the curve length of the original signal were related to damage evolution. Based on the above analysis, a damage index, namely, the FDbased damage assessment index, was defined by the fractal features of AE signals generated by damaged structures, including the curve length of the original signal and its FD. Fatigue tests of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) cables with AE sensors were performed to validate the . proposed approach. The time-history responses and frequency responses of the AE signals and the corresponding damage modes were analyzed during the entire cyclic loading process. The FD-based damage indices for all the FRP cables were obtained through analysis of the AE signals. The relationships of both the time-history responses and the frequency responses with the FD-based damage index were investigated. The results indicated that the FD-based damage index increased little with the number of loading cycles at the early loading stage but increased dramatically at the final stage of the fatigue test. The results of this article demonstrate that an FD-based damage index can quantify the evolutionary process of fatigue damage in FRP stay cables.

The state of the art in structural health monitoring of cable-stayed bridges

“…AE method for cable damage monitoring has been extensively investigated and implemented into practical cable-stayed bridges. Li et al [45,46] and Li and Huang [49] proposed an AE-based method to monitor the evolution of fatigue damage of steel stay-cables and carbon-fiber reinforced-polymer cables. The cable fatigue failure was well characterized by AE characteristic parameters such as the b value, Kurtosis index, and fractal dimension.…”

Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables

“…[2] evaluated the applicability of CFRP materials in long-span cable-supported bridges. Later, other scholars made more comprehensive studies on the possibility of applying CFRP in long-span bridges [3,4,5,6,7,8,9,10,11,12,13,14]. The mechanical properties of long-span cable-supported bridges built with CFRP cables have been gradually explained.…”

Fused empirical mode decomposition and wavelets for locating combined damage in a truss-type structure through vibration analysis

“…Some of these procedures are: the acoustic emission (Li et al, 2011), infrared thermography (Shih et al, 2000), ultrasound (Voigt et al, 2003), image processing (Nishikawa et al, 2012), eddy currents (Banks et al, 2002), and radiographs (Vossoughi et al, 2007); which are all used in assessing structural damage. However, the aforementioned methods possess several disadvantages; for instance, it is required that the location of the damage be known a priori, the section of the structure under inspection needs to be easily accessible and in several cases, the structures must be closed temporarily during its inspection (Curadelli et al, 2008).…”