The irregular wave disturbance attenuation problem for jacket-type offshore platforms involving the nonlinear characteristics is studied. The main contribution is that a digital-control-based approximation of optimal wave disturbances attenuation controller (AOWDAC) is proposed based on iteration control theory, which consists of a feedback item of offshore state, a feedforward item of wave for...

In the seismic risk assessment of structures, two main random variables are involved, namely the vulnerability of the structure and the seismic action. The aim of the study presented here is to analyze the seismic behavior of the jacket-type offshore platforms as an expensive and vital structure. Furthermore, the influence of the incidence angle of the seismic action is also investigated by usi...

development of a numerical model which describes launching of offshore jackets from barge is presented in this paper. in this model, in addition to capabilities of commercial softwares, water entry forces on jacket members and an implicit newmark solution technique are included. the results are in general agreement with other numerical software’s available (sacs). fluid forces acting on jacket ...

when a jack-up installed at a clay location and then leaves; it can create several meter deep footprints. in case of soft clay, the spudcan may have actually penetrated much deeper than the observed footprints. when the penetrated spudcan is pulled out, much of the soft remolded clay will flow around it and go back into the hole. this event, leaving a deep region of disturbed soil. the disturbe...

1.1 Offshore Structures: Offshore structures used for oil and gas extraction have the common function of providing a safe, dry working environment for the equipment and persons those operates the platform. Jacket supported drilling equipment as a guide for the piled foundations. The substructure referred to as the jacket is a three dimensional space frame made from large tubular steel members. ...

The sensitivity of the seismic response parameters to the uncertain modeling variables of pile-founded fixed steel jacket platforms are investigated using the Tornado diagram and the first-order second-moment techniques. The effects of both aleatory and epistemic uncertainty on seismic response parameters have been investigated for an existing offshore platform. The sources of uncertainty consi...

Physical model tests with the scale of 1:36 are carried out in the Near-Shore Wave Basin (NSWB) at Tainan Hydraulics Laboratory (THL) with the jacket-type offshore wind turbine foundation (jacket-type foundation) and the combination of hard or soft scour protection in the test area. Scouring around the jacket-type foundation exposed to wave and current was conducted in the NSWB with a mobile be...