Effects of Deck Shape and Oncoming Turbulence on Bridge Aerodynamics

The influence of deck geometry and oncoming turbulence on the flutter and buffeting behavior of cable-supported bridges were investigated by using wind tunnel section model test. In addition to smooth flow, homogeneous turbulent flow fields with various intensities and integral scales were generated for the aerodynamic coefficient measurements. The flutter wind speed and buffeting dynamic response were evaluated by incorporating the measured aerodynamic coefficients into the analytical model of a cable- stayed bridge. The results show that the width-to-depth ratio, B/H, of bridge deck plays an important role in bridge aerodynamics. Increasing B/H will improve the bridge stability. This study also indicates that the critical flutter wind speed increases monotonically with turbulence intensity, in other words, free stream turbulence tends to enhance the bridge's aerodynamic stability. Using the wind force coefficients and flutter derivatives obtained from smooth flow condition may result in larger buffeting estimation than those obtained from turbulent flows. These calculated results coincide reasonably with the measured results.