Investigation on the unstability of vortex induced resonance of high-rise buildings

Vortex induced vibration (VIV) as well as resonance were investigated by multi-degree-of-freedom (MDOF) aero-elastic models of supper high-rise buildings in a wind tunnel. The experimental data revealed that the structural displacement of the VIV was not ideally harmonic, and vortex induced resonance (VIR) occurred intermittently. Furthermore, it was showed that the vibration frequency did not lock the vortex shedding frequency completely in the VIV process, and the unstability of VIR was induced by the difference between the transient frequency of across-wind force and that of VIV displacement. In other words, the two frequencies cannot maintain equilibrium once they are equal to each other. Finally, a mathematical model considering multiple factors related to the VIV was established to predict the VIR occurrence probability of high-rise buildings.