Effect of non-linearity in restoring force on dynamic response of SFT

In case of SFT (Submerged Floating Tunnel) moored by inclined tension legs, unpredictable slack and snap are occasionally observed in experiment under severe wave condition. The authors assume that the non-linearity in restoring force is caused by the self-deformation of tension leg, usually called catenary curve, decided by the balance of self-weight and buoyancy of leg. In this paper, the non-linearity in restoring force is investigated first with varying the self-weight and buoyancy as well as the inclination angle of tension leg. The effects brought by the non-linearity in restoring force on the dynamic characteristics of SFT is discussed and the dynamic response of SIT due to wave is compared with those assuming its linearity. As a conclusion, how the non-linearity affects on the dynamic response of SIT is reported as well as some important findings.