A unified approach for 3D stability and time domain response analysis with application of quasi-steady theory

This paper focuses on a general quasi-steady approach for evaluation of three-dimensional (3D) galloping stability and buffeting response of elastic structures such as bridges and towers. The buffeting response is obtained as a time history, solving the generalised state equation of dynamic equilibrium. Its homogeneous solution allows evaluation of the galloping stability (linear formulation). The time histories of the wind velocities required for the buffeting analysis are numerically generated. Buffeting responses of the Millennium Footbridge over the Thames River in London, are simulated and the statistics of the results are compared with a conventional frequency domain method. Stability and accuracy of the integration are examined to establish the range of the solution parameters. The galloping stability analysis is verified on the I235 Pedestrian Bridge, Des Moines, Iowa, where the results are compared with the wind tunnel predictions.