Local wave propagation analysis in concrete-filled steel tube with spectral element method using absorbing layers – Part I: Approach and validation

Abstract

Concrete-Filled Steel Tube (CFST) members have been widely employed in high-rise buildings or long-span bridges as vertical or axial load-carrying components and the development of efficient interface debonding detection approach for CFST members has been a common concern. In recent years, wave propagation measurement based interface debonding defect approaches have shown their efficiency and efficient numerical simulation techniques on elastic wave propagation within CFST members are critical to understand the mechanism of the approaches. In this study, in order to efficiently investigate the effect of interface debonding on local elastic wave propagation within CFST members, a two-dimensional (2D) time domain spectral element method (SEM), where absorbing layers with increasing damping (ALID) is introduced to attenuate the wave reflection effect on boundaries, is developed at first. Then, the developed 2D time domain SEM with ALID is employed to simulate the wave propagation in a steel plate and an isotropic panel mimicking concrete core in CFST members. The effect of ALID on the attenuation of reflected Lamb waves in the steel plate and the bulk waves in the isotropic panel is validated. Finally, the local wave propagation in a substructure of the CFST model is numerically studied with the proposed 2D SEM with ALID. The dimensions and parameters of the ALID are determined and their effect on eliminating the reflected waves within the substructure excited by a single point load and a surface-mounted PZT patch actuator is demonstrated, respectively. The developed 2D time domain SEM with ALID provides efficient tool to simulate the local wave propagation in CFST specimens with interface debonding defects for understanding the mechanism of local stress wave measurement based interface debonding detection method to be discussed in the accompanying paper.