Crack identification in bridge girder beam by measurements of anti-resonant frequencies

Abstract

The antiresonance concept in cracked beams and its crack identification application in bridge girders represented by simply supported beams is presented in this paper. The beam model is adopted using Euler-Bernoulli beam theory, and a transversely edged crack is modelled by a rotational spring of compliance calculated from the crack depth. First, governing equations for anti-resonant frequency are established for examining anti-resonant frequencies versus locations of measuring response and excitation, as well as crack parameters. The obtained equations allow one to conduct a thorough analysis of the intricate dependence of anti-resonant frequencies on the locations where anti-resonant frequencies have been measured. It is exposed to the typical effect of a crack on anti-resonant frequencies compared to resonant ones. Finally, a crack identification approach for beams is developed using measured anti-resonant frequencies. The theoretical development is validated by experimental results and illustrated in numerical examples.