Aerodynamic performance of twin-box decks: A parametric study on gap width effects based on validated 2D URANS simulations. Issue 182 (November 2018) - Álvarez, A.J.
Abstract: 2D URANS simulations are conducted aiming to study the aerodynamic performance under smooth flow of twin-box decks depending on the gap distance between girders. The Stonecutters Bridge is taken as the reference geometry. In this parametric study, 14 gap to depth ratios in the range 0 ≤ G / D ≤ 9.70 are investigated, and for each geometry, 11 angles of attack in the range − 10 ∘ ≤ α ≤ 10 ∘ are considered. Specific goals of this research have been: identification of the fundamental flow features, study of mean and fluctuating pressure coefficients distributions, identification of the vortex shedding mechanisms and general aerodynamic characterisation based on force coefficients. The numerical results provided herein are validated with wind tunnel data previously reported in the literature, finding a good agreement. A critical gap to depth ratio at G / D = 2.35, in terms of aerodynamic response, was identified, which is consistent with the value reported in the literature for a different bridge based on wind tunnel tests. The obtained set of data provide a general picture of the expected aerodynamic performance of a twin-box deck depending on the gap distance and could be of great value at the early design stage of long-span cable-supported bridges. Highlights: 2D URANS simulations are used to obtain aerodynamic responses of twin-box decks. Force coefficients are obtained for 14 gap lengths at 11 angles of attack. Pressure distributions and vorticity fields help to identify main flow features. Two regions depending on the Strouhal numbers are identified.