Ocean Structures

This book addresses the concepts of material selection and analysis, choice of structural form, construction methods, environmental loads, health monitoring, non-destructive testing, and repair methodologies and rehabilitation of ocean structures. It examines various types of ocean and offshore structures, including drilling platforms, processing platforms and vessels, towers, sea walls and surge barriers, and more. It also explores the use of MEMS in offshore structures, with regard to military and oil exploration applications. Full-color figures as well as numerous solved problems and examples are included to help readers understand the applied concepts.

Ocean structures, including ships, boats, piers, docks, rigs and platforms, are subject to fair weather wind and waves, as well as violent storms. A scientific analysis of these structures, under varying conditions, requires a mix of civil engineering, physics and applied mathematics. Chapters by experts in these fields are presented which explore the nonlinear responses of ocean structures to stochastic forcing. Theoretical methods calculate aspects of time, frequency and phase space responses. Probabilities governed by stochastic differential equations are investigated directly or through moment correlations, such as power spectra. Calculations can also involve level crossing statistics and first passage times. This book will help scientists study stochastic nonlinear equations and help engineers design for short term survivability of structures in storms and long life in the face of everyday fatigue.

Improvements in the design process as applied to ocean structures have received intense interest in recent years. Part of this interest stems from the growing realization that design on a purely deterministic basis is inadequate for structures sub ject to random loads, which are best described by statistical (or probability) methods. This book is an attempt to bridge the gap between present design practices and available analytical techni ques (which may be exploited to improve present procedures). The book itself is an outgrowth of a set of notes prepared for an intensive short course presented over the past three years by the Engineering Extension Division of the University of California at Los Angeles, California. The ensuing presentation is composed of four parts. The material begins with a review of the physical environment (winds, surface gravity water waves and currents) for which engineering type formulations are presented. Hindcasting and forecasting techniques using spectral concepts are included. Special problem areas are enumerated.

This book focuses on: (1) the physics of the fundamental dynamics of fluids and of semi-immersed Lagrangian solid bodies that are responding to wave-induced loads; (2) the scaling of dimensional equations and boundary value problems in order to determine a small dimensionless parameter ε that may be applied to linearize the equations and the boundary value problems so as to obtain a linear system; (3) the replacement of differential and integral calculus with algebraic equations that require only algebraic substitutions instead of differentiations and integrations; and (4) the importance of comparing numerical and analytical computations with data from laboratories and/or nature.

At the FIP Symposiu m on Concrete Sea Structures, which was held on 28-29 September 1 972 in Tbilisi, Georgia, the participants unanimously agreed that c oncrete was bound to play a major if not the leading part in the rapidly developing field of offshore construction. It was also agreed that the discovery of oil and gas in the North Sea had produced an immediate and exciting challenge in the demand for the construction of fixed structures in marine environments which, in terms of hostile natura! forces, would far exceed anything tackled by engineers to date. It was therefore decided to set up an FIP Commission on Concrete Sea Structures under the chairmanship of Mr Fr,óde Hansen which would report to the FIP Seventh Congress in New York in May 1974 . It seemed natura! to divide the tasks of the Commission into three working groups: Design, Materials, and Construction Methods. It soon became apparent that the demands for structures subjected to deep and hostile waters were so great and so pressing that it was decided to accelerate the work of the Design and Materials Working Groups, and to produce the first edition of these Recommendations before the New York Congres s . The Chairmen for the two Working Groups were Mr Kurt Eriksson and Dr Odd Gjprv respectively. The publication of these Recommendations has been made possible by the li vely interest of these two groups and by the valuable assistance of Mr D. Palmer and Mr B. Spratt of the C ement and Concrete Association and Mr M. D. Hazen of Sir Robert McAlpine & Sons Ltd. The Recommendations have been published with the approval of the FIP Administrati ve Council. The work of the Construction Methods Working Group has not been included in this edition since practical construction experience in this most challenging field is still quite limited. The successful completion of the Ekofisk Storage Tank has added tremendously to obtaining practical experience, and this, with the fact that two larger concrete offshore platforms will soon be under c onstruction, offers the promise that future editions will be augmented by some very valuable practical construction experience.

Stochastic Dynamics of Marine Structures is a text for students and a reference for professionals on the basic theory and methods used for stochastic modelling and analysis of marine structures subjected to environmental loads. The first part of the book provides a detailed introduction to the basic dynamic analysis of structures, serving as a foundation for later chapters on stochastic response analysis. This includes an extensive chapter on the finite element method. A careful introduction to stochastic modelling is provided, which includes such concepts as stochastic process, variance spectrum, random environmental processes, response spectrum, response statistics and short- and long-term extreme value models. The second part of the book offers detailed discussion of limit state design approaches, fatigue design methods, the equations of motion for dynamic structures and numerical solution techniques. The final chapter highlights methods for prediction of extreme values from measured data or data obtained by Monte Carlo simulation.