3D flutter analysis of bridges by spline finite-strip method

This paper presents a numerical analysis procedure for the 3D flutter analysis of bridges based on the spline finite-strip method. The finite-strip method has been extended, for the first time here, to the area of bridge aerodynamics in wind engineering. In this application, the spline finite-strip method is adopted to model the bridge girder. A significant improvement of the present formulation is that the effects of the spatial distribution of the aerodynamic forces on a bridge deck structure can be taken into account by distributing the aerodynamic forces over the cross section of the bridge deck. The flutter problem is solved by the PK-F method. Through iteration of the flutter determinant, the critical flutter wind velocity and the preflutter response of the bridge are determined. The frequencies and logarithmic decrement of the response over the range of wind velocity of interest are obtained. Numerical examples of a thin flat plate and a recently completed 423-m long-span cable-stayed bridge are presented to illustrate the reliability and accuracy of the proposed method. The results show that the present formulation has advantages over the typical equivalent beam finite-element models, particularly in the data preparation and the capability of the method to account for the spatial distribution of the aerodynamic forces across the cross section of the bridge deck. The potential of its future application is also discussed.