Numerical investigation on the aerodynamics of bridge decks

Abstract

Long span bridges are slender and flexible and are prone to the action of wind loads and excitations. The phenomenon of the flow of wind occurring on the decks mainly governs the overall aerodynamic stability of the bridge structure. Numerical methodologies related to solving the wind engineering problems often referred to as Computational Wind Engineering (CWE) have experienced vast development and more reliability, as they tend to have higher order accuracies as that of the wind tunnels. This thesis focuses on numerically investigating the bluff body aerodynamics of bridge deck cross section. Computational Fluid Dynamics (CFD) is the numerical tool which is used in the study of solving the wind flow problem where wind is considered as a fluid. The study involves a numerical simulation of the Great Belt East Bridge (GBEB) deck cross section for a Reynolds Number of 1x105. The simulation was done by RANS (Reynolds Averaged Navier Stokes Equation) and the LES (Large Eddy Simulation) using the developed mesh which was tested for Grid Independency. The aerodynamic coefficients of the Great Belt East Bridge (GBEB) have been evaluated and were compared with the experimental and simulation results from literatures and were found to be in good agreement. The numerical simulation approach followed was thus validated. A parametric study on the geometry of the deck cross section wherein several deck cross sections were developed by making modifications in its geometry, keeping the B/H ratio constant and equal to that of the GBEB was carried out. The study was performed with an aim to propose an aerodynamically stable or optimum deck cross section. newline