SUMMARY
The offshore floating platform is the key equipment in offshore and gas development. The significant heave motions occur with the excitation of wind and waves, which will affect the safety of a riser system. A direct acting tensioner can be applied to reduce the effects on the riser system and be widely used on different kinds of offshore platforms. Based on the analysis of the structure and working principle of a direct acting tensioner (DAT), the nonlinear dynamic performance of DAT riser system was studied. Additionally, the dynamic model of the DAT riser system is established and the dynamic response was gained by the numerical integration method. The differences of dynamic responses were compared between a linear model and a nonlinear model. The response on different side of the equilibrium position is asymmetric because of the nonlinear stiffness of DAT. The results can be helpful for the design of DAT.