Methods for Hybrid Aeroelastic Analysis of Structures

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The aeroelastic behavior of slender structures such as long-span bridges needs to be accurately predicted as part of their design. They can develop significant vibrations when exposed to atmospheric wind flow and therefore realistic models for the prediction of wind-structure interaction phenomena such as vortex-induced vibrations, buffeting and flutter are required. Typical methods for aerodynamic analysis are empirical models, experimental (wind tunnel) models and, more recently, numerical (Computational Fluid Dynamics, CFD) models. For the analysis of a structure these can be combined and need to be coupled to structural dynamics models. The influence of the individual model components on the global model prediction and its quality can be quantified by means of sensitivity analyses. Promising concepts to control the overall prediction quality are adaptive or hybrid modelling approaches, where the model components are chosen such as to keep a balance between prediction quality and efficiency. The aim of this project is to develop a general model framework to compute the dynamic structural response due to wind using a hybrid modelling approach which combines different models that can be flexibly selected and exchanged to balance prediction accuracy and computational speed. This shall be done with the help of meta-modelling techniques employed to replace, partially or fully, computationally expensive Vortex Particle CFD simulations with mathematical expressions, thus dramatically reducing computational effort without significantly compromising prediction accuracy. Neural networks are a category of machine learning techniques whereby the network is here used as a meta-model for the different forcing terms in the wind-structure interaction. Sensitivity analyses shall be adopted to quantify the influence of individual input parameters on the model prediction to guide the model selection process. Developed meta-models will be validated against suitable reference models such as wind tunnel tests. These are employed in a pseudo-3D structural modelling, which allows the analysis to be performed by simultaneously considering aerodynamic admittance, motion-induced forces and vortex shedding. The aerodynamic analysis of a 3D structure can thus be performed in time domain based on a flexible hybrid combination of aeroelastic models arranged at the structural elements, with the meta-models providing high computational efficiency. The modelling framework is generally applicable to any line-like structure such as long-span bridges, towers and masts and has significant potential for future applications to wind engineering problems.