New damage indices and algorithm based on square time-frequency distribution for damage detection in concrete piers of railroad bridges

Abstract

SUMMARY This paper presents a new algorithm based on square time–frequency distribution to detect damages in concrete piers of railroad bridges. In addition, two new damage indices are proposed in this research. The algorithm and damage indices are described and corroborated using finite element model of Qotour railroad bridge. To create the finite element model according to the current condition of the Qotour railroad bridge, extensive in situ measurement results and laboratory tests were used. Some seismic damages were considered in the concrete piers of the model. The results indicate that the algorithm and damage indices can identify all damages from severe to small accurately. The proposed algorithm and damage indices are shown to be not sensitive to noise and even in case of noise-polluted response signal are working properly. The proposed algorithm only uses the response signals without the need for recording the excitation forces. In addition, according to the algorithm, there is no need to create an analytical model of the bridge for damage detection. This feature in modeling of bridge structures and especially complex bridge, which is associated with problems, is very useful. Copyright © 2014 John Wiley & Sons, Ltd.