Wave impact on horizontal platforms

Wave impact on horizontal platforms

De Rooij, O.V.

Civil Engineering and Geosciences

Hydraulic Engineering

2001-10-01

This project is about wave impact on horizontal platforms. It investigates the interaction between ocean waves, mainly during hurricanes, and harbour jetties in coastal areas. Various types of loads can be identified when waves hit these kinds of coastal structures. The focus in this report will be on vertical loads (upward and downward) on platform decks. This subject has only had little coverage in studies on hydraulics or wave mechanics so far. The studies that are available differ SUbstantially in everything from their origin and their goal, to their points of interest and their methods used. All this makes that, before adding a new study to this list, it is very important to thoroughly review the available literature to see which theories have been tested, which references have been looked at, what methods have been used and what results were obtained. Chapter 1 starts with the introduction to the project, describing the problem under investigation, the goal to be achieved and the approach followed to do this. Chapter 2 contains a literature review. This review summarises the work done on the SUbject from around 1970 to today by various researchers and groups of researchers. The first thing that strikes in this review is the non-uniformity and the lack of a clear framework that characterises most projects, at least, as far as the presentation of the respective projects in research papers is concerned. Researchers often follow their own trail, failing to comment on findings by others. Issues that are of considerable importance to the exact understanding of the phenomenon are sometimes not commented on or are solved without proper reasoning. These issues and the way this report deals with them are listed in the end of this chapter. The literature review does not end in a complete understanding on how wave loads should be calculated. It shows a list of theories, analytical attempts and model tests trying to solve the problem, in lots of different ways for lots of different reasons. In chapter 3 the current state of knowledge is summarised. The wave impact process is separated into three components: Fpeak, the initial peak force, F+, the slowly-varying positive load and F-, the negative load. For each of these components, the parameters that influence their shape and magnitude are listed. After this, an overview will be given on how well the various studies found in the literature deal with the issues mentioned above. This will then result in a ranking which reflects the usability of their results. These results will then be quantified for a couple of wave conditions, to see how the models compare. Chapter 4 will describe model tests performed in the labs of HR Wallingford near Oxford. These tests have not been commissioned or designed especially for this project, but many interesting findings have been obtained from it nevertheless. The next chapter, chapter 5, shows the way a model predicting the three impact force components could look like. In important notion here is that the bounds of the validity of this model are defined by the characteristics of the scale model it is derived from. The chapter ends with some guidelines for designing a harbour jetty. The last chapter, chapter 6, contains the conclusions and recommendations this project suggests.

ocean waves
harbour jetties
deck

http://resolver.tudelft.nl/uuid:63966443-add1-4881-b941-a5e0db30190a

Student theses

master thesis

(c) 2001 De Rooij, O.V.