Time-domain simulations of turbulence effects on the aerodynamic flutter of long-span bridges

Abstract Aerodynamic flutter instability has been a major concern for long-span flexible bridges, such as suspension and cable-stayed bridges, subjected to wind actions that result in the so-called self-excited forces. Though turbulence effects on bridge flutter have been studied in the last few decades, its true effects remain a debate due to the limitation of previous wind tunnel facilities, such as using turbulence scales that are too small in these experiments. In this paper, the characterizations of self-excited forces are presented in both the frequency-domain and in the time-domain. Then, the flutter analysis is conducted under both smooth flow and turbulent flow in order to investigate the effect of wind turbulence on the flutter instability. The effect of wind turbulence is directly modeled in the time-domain in order to avoid the complicated random parametric excitation analysis of the equation of motion used in previous studies. By comparing the results of different turbulence intensities with that of the smooth flow, it is found that the turbulence has a stabilizing effect on bridge flutter. The turbulence can change the vibration patterns and weaken the spatial vibration correlation to some extent. As a result, the critical flutter velocity can be increased by 5% to 10% over that under smooth flow.