A simple numerical model for the aeroelastic analysis of cable-stayed bridges

Abstract The purpose of this paper is to establish a methodology for the aeroelastic analysis of cable-stayed bridges using a simplified model derived from full-size finite-element models. Initially, classical modal analysis is performed using finite-element modelling. A priori selection of the relevant vibration modes for the study of the particular case of aerodynamic loading should be considered next, demanding expertise from the analyst. In this paper only the aerodynamic forces for the classical flutter analysis will be studied. Then, a reduction technique is applied to supply a set of two coupled homogenous equations of motion about the equilibrium configuration. An analytical formulation for modelling the aerodynamic loads within the finite element is assumed in conformity with classical flutter analysis. Once the reduced aeroelastic model is obtained, a systematic survey of the related complex eigenvalue problem is pursued to characterise the flutter condition and the critical wind velocity. The procedure is programmed, using symbolic computation, so that it can properly handle output files of numerical modal analysis for typical finite element models of cable-stayed bridges. A simple numerical example is then explored to illustrate the procedure.