Drive-by deflection estimation method for simple support bridges based on track irregularities measured on a traveling train
Kodai Matsuoka, Hirofumi Tanaka
Abstract
Bridge deflection under train passage is a typical index of the bridge’s structural performance that can be measured from the ground with considerable effort and expense. This study develops a novel drive-by bridge deflection estimating method based on track irregularities measured on a moving train as a significantly efficient bridge deflection measuring method. First, theoretical analysis demonstrates that the difference in track irregularities observed by the first and last vehicles of a train is proportional to the bridge deflection that the train travels through when the dynamic response of the bridge is small and quasi-static response is predominant. Furthermore, it is stated that the proportionality coefficient is only determined by the train wheelset arrangement and the bridge span. Based on the different peaks of track irregularities observed at the first and last vehicle of a train, a unique method for estimating bridge deflection after canceling the track irregularity components other than bridge displacement has been devised. The accuracy verification by vehicle-bridge interaction simulation shows that the proposed method can be applied to track irregularities measured by a traveling train at a speed of <150 km/h with a standard deviation of <0.2 mm measurement error. Finally, the proposed method is applied to actual railway track irregularities as measured by the first and last vehicles of a train traveling at ∼ 100 km/h. The maximum deflections of five bridges estimated from the track irregularity are shown to be in good agreement with the on-site deflection measurement results, which were separately performed, with an error of <10%.