Nonlinear Aerodynamic Analysis of Bridges under Turbulent Winds: the New Frontier in Bridge Aerodynamics

Traditionally, the estimation of wind induced buffeting response and analysis of flutter instability have been conducted in the frequency domain utilizing linear approaches. These approaches are limited to linear structures in which nonlinearities in aerodynamic forces are ignored. In this study, a time domain analysis framework for predicting the flutter and buffeting responses of bridges under turbulent winds is presented, in which the nonlinear aerodynamics with respect to the effective angle of incidence is included. The nonlinear unsteady aerodynamic forces are modeled based on the static coefficients, flutter derivatives and admittance functions along with the spanwise correlations at varying angles of incidence. The analysis framework incorporates frequency dependent parameters of unsteady aerodynamic forces by utilizing a rational function approximation technique. A comparison with the conventional linear approach is made through response analysis of a long-span suspension bridge.