Contributed Talk


Numerical models for flutter stability analysis of long-span bridges


Tajammal Abbas, Guido Morgenthal
Bauhaus-Universitaet Weimar, Germany

Abstract

Long-span cable supported bridges are prone to aerodynamic instabilities caused by wind and this phenomenon is usually a major design criterion. If the wind speed exceeds the critical flutter speed of the bridge, this constitutes an Ultimate Limit State. The prediction of the flutter boundary therefore requires accurate and robust models. This paper aims at studying various combinations of models to predict the flutter phenomenon. The main objective of aeroelastic instability analysis is to find the wind speed at which instability occurs. Wind tunnel tests are the traditional basis for the analysis of structures under wind actions. These methods are considered relatively accurate compared to the other methods. However, such tests are expensive and cannot reproduce fully the physics of the full-scale problem. With the advancement in the computer modelling and the processing power and by using the principles of Computational Fluid Dynamics (CFD), it is now possible to study wind effects on structures in relatively less time. These methods are also efficient, repeatable and economical. Numerical simulations can be used in place of wind tunnel investigation for the fundamental studies. The usefulness of numerical methods in understanding the genesis of aerodynamic phenomena and quantifying effects has now been relatively widely accepted. Numerical simulations using the Vortex Particle Method (VPM) are a common approach to simulating 2D wind flow over a cross-section, allowing the vortex shedding process to interact with the structural motion. In conclusion, the model choice for a given practical analysis scenario will be discussed in the context of the analysis findings.



ISSN 1611 - 4086 | © IKM 2015