Investigation of the aerodynamic analysis of super long-span bridges by using ERA-based reduced-order models

Reduced-order models (ROM) are computationally efficient techniques, which have been used widely for predicting unsteady aerodynamic response of airfoils and wings. However, they have not been applied extensively to perform unsteady fluid dynamic analysis of super long-span bridges. This paper discusses the application of a reduced-order computational fluid dynamics (CFD) model based on the eigensystem realization algorithm (ERA) in the aerodynamic analysis of three well-studied long-span bridges. The aerodynamic impulse responses of the Great Belt Bridge (GBB) and Stonecutters and Messina Strait Bridges were used to construct the aerodynamic ROM, and then the aerodynamic forces due to arbitrary inputs and their corresponding flutter derivatives were evaluated and compared to those of the model coupled with an advanced CFD code. Results demonstrate reasonable prediction power and high computational efficiency of the technique that can serve for preliminary design, optimization, and control purposes. The methodology described in this paper has wide application in many civil engineering problems where flexible structures interact with unsteady fluid mechanical phenomena