Investigation Into the Effect of Initial and Secondary Ship Impact on the Integrity of a Typical Jack-Up Platform

In this paper finite element analysis of a typical jack-up platform under different impact scenarios are performed using ANSYS software and the effect of various mechanisms in absorbing the energy of collision is determined. A 3D model of Iran-Khazar Jack-up operating in Caspian Sea is prepared. Dynamic nonlinear analyses, including geometric and material nonlinearity, are performed. The effects of preloading due to platform weight and environmental wave and current loading before collision are applied. In first collision between ship and studied jack-up, for impact to chords (leg-like vertical elements) as well as to braces (diagonal or horizontal elements), the main energy absorption mechanism is overall deformation of structure. For second impact it is assumed that the rebounded ship moves again toward the platform with relative wave induced velocity and worst impact scenario is considered. The results show that leg chords can resist to the second impact and the platform in both initial and secondary impacts is damaged locally such as indentation of the chord wall and the whole structure is safe.