Numerical wind tunnel for aerodynamic and aeroelastic characterization of bridge deck sections

Abstract

The aim of the present study is to propose a reliable engineering procedure to analyze bridges subjected to wind loads by-passing the expensive wind tunnel tests thanks to numerical simulations. These exploit Kratos, a free multi-physic FEM code developed by the Kratos Team at CIMNE in Barcelona, and, specifically, an adaptation to the long-span bridge case of its numerical tool for simulation of in-wind ultra-lightweight structures developed within the uLites project (supported by the Research Executive Agency in the Seventh Framework Programme of the European Union, SP4-Capacities, Research for the benefit of SMEs, FP7-SME-2012 GA-314891, see http://www.cimne.com/websasp/ulites/). Time histories of the forces induced by the flow around the sections are used to calculate aerodynamic and aeroelastic parameters through statistical, frequencies extraction and fitting algorithms. Several analyses have been performed to derive rules for a reliable and stable evaluation of these aggregated parameters for engineering purposes. Results obtained for the sections of Great Belt Bridge (Denmark) and of the bridge on A31 highway over Adige river (Italy) are shown. Both static analyses (CFD procedure with fix boundaries) and imposed-displacements analyses (CFD with ALE) give results that are comparable with those coming from wind tunnel testing and from literature; evaluated parameters also manifest regular trends and values little influenced by CFD setting. These facts represent proofs of the reliability of the proposed procedure.