Evaluation of dynamic loads on a skew box girder continuous bridge Part I: Field test and modal analysis

Field measurements were carried out to evaluate dynamic loads on an existing skew box girder continuous bridge. This paper presents the experimental procedure, the data acquisition system, the calibration test, the modal analysis and the load distribution in a transversal direction. A three-axle heavy truck was hired for use in the test to calibrate the field measurements. The static and dynamic bending moments of the tested bridge induced by the calibration truck were obtained. The relationship between the measured strain and bending moment were determined. Information on the dynamic behaviours of the bridge were obtained from an experimental and theoretical modal analysis. The influence of skewness on the static and dynamic behaviours of the bridge as well as on the load distribution in the transversal direction for the calibration truck and in-service vehicles was investigated. It was found that the influence of skew in both the static and dynamic behaviours of the bridge within the skew angle range of 0∘–30∘ is very small.