New frontiers in aerodynamic tailoring of long span bridges: an advanced analysis framework

Abstract

Significant developments in bridge aeroelastic analysis have been made utilizing realistic aerodynamic force modeling for bridges with bluff sections under turbulent winds. With these developments as a background, this paper highlights state-of-the-art developments in the aeroelastic analysis and identifies new frontiers in aerodynamic tailoring of long span bridges. Challenges in the aeroelastic analysis are pointed out that include: the modeling of aerodynamic forces excited by non-stationary wind fields such as hurricanes and thunderstorms and/or for bridges located in complex topography conditions; consideration of nonlinearities in both structural dynamics and aerodynamics; and the ubiquitous issues related to turbulence. In response to these challenges, an advanced analysis framework is offered that focuses on the needs for modeling of aerodynamic and structural nonlinearities, and the effects of turbulence on long span bridges. r

Improved Understanding of Bimodal Coupled Bridge Flutter Based on Closed-Form Solutions

“…These numerical studies provided a basis for the empirical formula suggested by Selberg ͑1961͒ for estimating the critical flutter velocity of bridges with a flat plate section. The introduction of flutter derivatives and the development of their identification schemes through wind tunnel testing offer realistic modeling of aerodynamic forces on bluff bridge sections ͑e.g., Ukeguchi et al 1966;Sabzevari and Scanlan 1968;Scanlan and Tomko 1971;Scanlan 1978Scanlan , 1993Davenport and King 1984;Sarkar et al 1994;Jakobsen 1995;Matsumoto et al 1995;Chen and Kareem 2002͒. In recent years, multimode coupled flutter analysis frameworks have been developed for advanced prediction of coupled bridge flutter, integrating the structural characteristics of multiple modes and the experimentally obtained aerodynamic forces on bridge sections ͑e.g., Miyata et al 1994;Jones et al 1998;Chen et al 2000a, b;Chen and Kareem 2003a;Diana et al 1999͒. The solution of the equations of motion of aeroelastic bridge systems through a complex eigenvalue analysis provides information on how the self-excited forces influence modal frequencies, damping ratios, and intermodal coupling as wind velocity increases ͑e.g., Chen et al 2000a͒.…”

Applications of reduced order models in the aeroelastic analysis of long-span bridges

“…The first systematic framework to study bridge aeroelasticity analytically started with the pioneering works of Davenport (1962) and Scanlan (1978, 1987) concerning bridge buffeting and flutter, which led to a number of analytical developments in bridge aerodynamic/aeroelasticity using realistic aerodynamic force modeling of bridges under turbulent winds. Analytical aeroelastic analysis in both time and frequency domain is still attractive for scholars, and the results of 2D and 3D studies are comparable to the available experimental data (Chen and Kareem, 2003; Miyata, 2003; Larose and Livesey, 1997; Chen et al , 2000).…”

Stability of two-degrees-of-freedom aero-elastic models with frequency and time variable parametric self-induced forces

“…Essentially, the second group uses aero-elastic coefficients named as direct and indirect flutter derivatives (FD), see e.g. Brownjohn and Bogunovic-Jakobsen (2001) or Chen and Kareem (2003) and solves the "combined time-frequency" system by an iteration directly determining the critical velocity and the frequency of the resulting coupled heave-pitch motion. Several other solutions have been proposed by different authors.…”