CFD evaluation of the lock-in phenomenon of a bridge under wind load

Abstract

This paper presents a methodology for the numerical analysis of the serviceability conditions of slender structures under wind actions, having in consideration the possibility of occurrence of synchronized phenomena (lock-in) due to vortex-shedding. The computational model used in the aeroelastic analysis of slender structures is based on the appropriate conjugation of an algorithm of Computational Fluid Dynamics (Control Volume Method) with an algorithm of linear or geometrically non-linear analysis of structures. This new methodology was developed in order to evaluate the ultimate limit states of instability, specifically the critical velocity of aeroelastic instability. Now, this methodology is also applied to the safety checking of the vibrations serviceability limit state of a simply supported bridge with a rectangular cross-section (B/D=6), under wind load considering their fundamental frequency. In particular, it will be evaluated the range of this synchronized phenomena, the peak value of acceleration obtained and: i) the time to start the phenomena; ii) the fully developed time; iii) and the corresponding time step. Some of the most interesting results associated with the evaluation of the corresponding response acceleration are also presented and compared with available human body acceptance criteria for vibrations (comfort evaluation) present in the technical literature.