Abstract:In order to research the Vortex-Induced Vibration (VIV) characteristics of top tension riser subjected to marine current, modal tests of VIV were conducted in a large wave-current flume. The model riser with changing top tension was attached vertically to the supporting structure and different external current velocities acting on the model. The cylinder model was equipped with six measured stations which are distributed averagely along the riser and each was formed by two strain gauges to measure both in-line direction and cross-flow direction oscillation responses. Through wavelet transform analysis, VIV frequencies, amplitudes of oscillation and coupling vibration rule between X and Y motions were obtained. The effect of varying top tensions on the natural frequency and VIV response were investigated.