Multimode flutter of long-span cable-stayed bridge based on 18 experimental aeroelastic derivatives

A Simple Analytical Approach to the Aeroelastic Stability Problem of Long-Span Cable-Stayed Bridges

“…Following a well established approach [18][19][20], each aerodynamic action can be described as the superposition of: (1) a steady component; (2) a turbulent or fluctuating component, including buffeting effects due to turbulence in the approaching wind and self-induced time-dependent components ascribable either to vortex shedding or to structureinduced turbulence (signature effects); (3) self-excited or aeroelastic force components, strongly dependent on the structural motion. As is customary in aeroelastic analysis of long-span bridges [11][12][13][14][15][16][17][18][19][20], it will be assumed that: buffeting forces (2) are not directly coupled with the aeroelastic ones (3), self-induced buffeting forces are negligible, and buffeting forces due to the turbulence in the approaching wind are independent on the structural motion and they produce a negligible variation in bridge configuration. Accordingly, only the aeroelastic self-excited forces are responsible for the aeroelastic stability of the bridge.…”

“…Accordingly, only the aeroelastic self-excited forces are responsible for the aeroelastic stability of the bridge. Assuming that oscillations of the bridge deck under wind loads are harmonic, ω being the circular frequency, the aeroelastic forces (denoted by subscript ae) can be completely represented as [12][13][14][15][16][17]:…”

“…In detail, the existing Jingsha Bridge (China) [52,57] and the bridge scheme addressed by Mishra et al in [17,58] have been analyzed.…”

“…From an aerodynamic point of view, Scanlan proposed a frequency-domain model of the self-excited wind forces which couple with the structural dynamics, by introducing frequencydependent empirical functions (namely, the flutter derivatives), widely employed in specialized literature for analyzing bridge flutter mechanisms [11][12][13][14][15][16][17][18][19][20][21][22]. Generalizing the indicial concepts proposed by Wagner for a flat thin airfoil [23], alternative time-domain approaches have also been proposed, based on empirical time-dependent indicial functions of the bridge's cross-section [19,20,24].…”

“…A number of multi-mode formulations have been recently proposed and the influence of modal coupling on flutter mechanisms has been analysed from many authors [11][12][13][14][15][16][17]. Nevertheless, these approaches usually need the identification of a large number of bridge modes as well as an accurate evaluation of modal participation and interaction within the instability phenomenon.…”