Aerostatic instability measurement and analysis of a cable-stayed full-bridge aeroelastic model in natural wind

A novel experimental method for wind engineering research of bridges was proposed several years ago, i.e., studying the wind-resistant performance of bridges based on larger-scale full bridge aeroelastic models in the natural wind. A 1:50 scaled aeroelastic cable-stayed bridge model, measuring 41.76 m in length and 6.0 m in height, has been constructed at the Outdoor Experimental Bases for Bridge Wind Engineering (OEBBWE). Based on this model, the entire process for aerostatic instability was recorded in natural wind, and the on-site wind speeds, wind directions, and wind attack angles, as well as accelerations, displacements, and cable forces of the bridge model, were comprehensively collected. Upon the onset of aerostatic instability, the on-site instantaneous wind speed, wind yaw angle, and wind attack angle were measured to be 17.5 m/s, 8.7°, and 3.2°, respectively. A high instantaneous wind speed, a small wind yaw angle, and a positive wind attack angle were key factors leading to the collapse of the bridge model. When comparing the measured critical wind speed with the theoretical methods, it is found that the linear theory overestimates the critical wind speed. In contrast, the nonlinear finite element method yields a closer prediction of 22.5 m/s, though this value remains higher than the measured result. This discrepancy can be attributed to the inherent uncertainties and variability in natural wind conditions, including fluctuations in wind speed, wind direction, and wind angle of attack, as well as turbulence characteristics and spanwise coherence.