Transient Impact Response of Bridge I-Girders with and without Flaws
Publication: Journal of Bridge Engineering
Volume 2, Issue 4
Abstract
This paper presents both numerical and experimental studies of the transient response of concrete I-girders with and without flaws subjected to transverse elastic point impact. These studies were aimed at evaluating the capability of using the impact-echo method for integrity testing of concrete I-girders. Numerical and experimental studies were performed first to gain an understanding of transient stress wave propagation in solid I-girder segments. Experimental studies were carried out on full-size reinforced-concrete I-girder segments containing flaws at known locations. Results obtained from these studies show that the transient response of a solid I-girder subjected to impact on the bottom surface is composed of a number of resonant frequencies caused by cross-sectional modes of vibration. Among these frequencies there is a predominant frequency, and its value depends on the cross-sectional geometry and dimensions of the bottom portion of the I-girder for a given P-wave speed in concrete. It is also shown that the presence of a flaw disrupts the modes of vibration. A shift of the predominant frequency to a lower value is a key indication of the presence of the flaw. In addition, multiple wave reflections between the impact surface and the surface of the flaw produce a large amplitude peak in the spectrum at the frequency corresponding to the depth of the flaw, and thus make it easy to locate the flaw.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 2 • Issue 4 • November 1997
Pages: 131 - 138
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Nov 1, 1997
Published in print: Nov 1997
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