Torsional Response of Long Span Bridges in Presence of Turbulence

Abstract

The effects of spanwise wind correlation and turbulence intensity on the stability of the torsional response of long span bridges are studied. An aerodynamic coefficient model is used for the self‐excited forces. Wind turbulence is assumed to be a wide‐band, weakly stationary in time, random field whose correlation time is much shorter than the relaxation time of the bridge. The equation for the uncoupled torsional response is transformed into an Ito stochastic differential equation. The first‐ and second‐order moments of the response are obtained using standard methods of Ito calculus. An application is presented for the case of a particular long span bridge. Different levels of turbulence and spanwise wind correlation are used. For a constant turbulence level, reducing the spanwise correlation increases the critical wind velocity. For a constant spanwise correlation, increasing the turbulence level reduces the critical wind velocity.