Estimation of bridge static response and vehicle weights by frequency response analysis

Abstract

A methodology is developed to more accurately estimate the static response of bridges due to moving vehicles. The method can also be used to predict dynamic responses induced by moving vehicles using weigh-in-motion (WIM) techniques. Historically, WIM is a well-developed technology used in highway research, since it has the advantage of allowing for the stealthy automatic collection of weight data for heavy trucks. However, the lack of accuracy in determining the dynamic effect in bridges has limited the potential for its use in estimating the fatigue life of bridge structures and their components. The method developed herein amends the current WIM procedures by filtering the dynamic responses accurately using the Fast Fourier Transform (FFT). Example applications of the proposed method are shown by using computer-generated data. The method is fast and improves the predicted truck weight up to 5% of the actual weight, as compared to errors up to 10% using the current WIM methods.Key words: weigh-in-motion, digital filters, FFT, bridge dynamics, in-service testing.