Field measurement and wind tunnel study of aerodynamic characteristics of twin-box girder

Abstract

To investigate the aerodynamic characteristics of a twin-box girder, the Xihoumen suspension bridge with a main span of 1650 ​m, was selected as the research object in this study. The wind field characteristics and the wind pressure distribution on the girder surface were analyzed by comparing the field measurements and wind tunnel tests for two conditions, namely orthogonal wind and skew wind. Furthermore, the aerodynamic coefficients and admittance were studied, which fully revealed the aerodynamic characteristics of the twin-box girder. The field measurement at the bridge site showed that the wind field had a large angle of attack and deflection angle in most cases. The results from the wind tunnel tests under skew wind indicated that the yaw wind-decomposition method was not applicable in the case of large wind deflection angles. It was observed that the aerodynamic admittance obtained by the field measurement in the low frequency phase was significantly higher than that measured in the wind tunnel test; however, in the high frequency phase, both yielded similar results. This implied that the buffeting load of the girder would be underestimated in the low frequency band if the aerodynamic admittance value from the test was used.