Effects of structural nonlinearity and along-span wind coherence on suspension bridge aerodynamics: Some numerical simulation results

摘要

The response of suspension bridges to wind excitation is studied by means of numerical simulations with a specifically developed finite element program implementing full structural nonlinearities. A pure time-domain load model, linearized around the average configuration, is considered. The self-excited effects are included through the indicial function formulation, whereas the buffeting is considered according to the quasi-steady model. The response under turbulent wind, both fully and partially correlated, is evaluated through a Monte Carlo approach. A simplified structural model is considered, where only two cross-sections are modeled. This allows a high reduction of the number of degrees of freedom (DoFs) but maintains many characteristics of the true bridge, precluded to the classical 2-DoF sectional-model (e.g. considering more than two modes, including structural nonlinearities, introducing along-span wind coherence). The case studies of a long-span suspension bridge and a light suspension footbridge are analyzed. It is observed that structural nonlinearities deemphasize the presence of a critical flutter wind velocity, as they limit the oscillation amplitudes. On the other hand, fully correlated flow may produce an important underestimation of the structural response. (c) 2006 Elsevier Ltd. All rights reserved.