Effects of irregular nonlinear ocean waves on the dynamic performance of an example jack-up structure during an extreme event

•Develop second-order constrained NewWaves to capture irregularity and nonlinearity of ocean waves.•Assess the effects of wave nonlinearity on the dynamic responses of a sample jack-up.•Calculate of the failure probability of the sample jack-up and compare the results for linear and nonlinear waves.•Compare the dynamic amplification factor (DAF) of the sample jack-up for linear and nonlinear waves.

In this paper, the effects of the nonlinearity and irregularity of ocean waves on the nonlinear dynamic response of a jack-up structure are investigated. A finite element model of a sample jack-up platform is formulated in USFOS to include the effect of material and geometrical nonlinearity and spudcan-soil-structure nonlinear interactions. Second-order NewWave and Constrained NewWaves are developed to simulate the nonlinearity of ocean waves. The nonlinear water surface and water particle kinematics for a typical extreme wave condition are estimated and implemented in the developed model, and the results are compared in terms of deck displacements. The results obtained from the analyses indicate that the inclusion of wave nonlinearity and irregularity for the studied case produces a considerable increase in the deck displacements and in the probability of failure of the sample jack-up structure.