Breaking wave loads at vertical seawalls and breakwaters

On coasts with high tidal ranges, or subject to high surges, both still water levels and waves can be important in assessing flood risk; their relative importance depends on location and on the type of sea defence. The simultaneous occurrence of large waves and a high still water level is therefore important in estimating their combined effect on sea defences. Wave period can also be important in assessing run-up and overtopping, and so it is useful also to have information on the joint distribution of wave height and period. Unless the variables are either completely independent or completely dependent, multivariate extremes are difficult to predict directly from observational data, as there may be too few events of the relevant type amongst the observations. In the past, the fitting and extrapolation of the dependence functions between the variables has often involved complicated and/or subjective approaches. This paper presents a method for joint probability analysis, using a Monte Carlo simulation approach, based on distributions fitted to water level, wave height and wave steepness, and to the dependence between them. RESUME

The joint probability of waves and water levels in coastal engineering design La probabilite conjointe de la houle et des hauteurs d'eau dans la conception de defences cotieres

On coasts with high tidal ranges, or subject to high surges, both still water levels and waves can be important in assessing flood risk; their relative importance depends on location and on the type of sea defence. The simultaneous occurrence of large waves and a high still water level is therefore important in estimating their combined effect on sea defences. Wave period can also be important in assessing run-up and overtopping, and so it is useful also to have information on the joint distribution of wave height and period. Unless the variables are either completely independent or completely dependent, multivariate extremes are difficult to predict directly from observational data, as there may be too few events of the relevant type amongst the observations. In the past, the fitting and extrapolation of the dependence functions between the variables has often involved complicated and/or subjective approaches. This paper presents a method for joint probability analysis, using a Monte Carlo simulation app...

The joint probability of waves and water levels in coastal engineering design

This paper discusses wave impacts on vertical and composite breakwaters and related coastal structures. It describes types of vertical walls in use, with particular reference to older walls that may be much more influenced by wave impacts. Methods to estimate wave forces are identified. Analysis of performance suggests that these under-predict wave impact loads, and cannot identify combinations of geometry and wave conditions which lead to impacts. Comprehensive 2-dimensional hydraulic model tests have been conducted using random waves to measure wave pressures (and other responses) on a wide range of simple and composite vertical walls. The test results have been used here to: • Identify the ranges of geometry and wave conditions which lead to wave impacts; • Develop a simple method to estimate wave forces under impact conditions. Analysis of % of impacts has defined a new design diagram to identify wave conditions and wall / mound geometries which cause impacts. These results are intended for engineers analysing vertical or composite walls in deep water, in harbours, or along the shoreline.

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New design methods for wave impact loading on vertical breakwaters and seawalls

Vicinanza, D., Norgaard, J.H., Contestabile, P. and Andersen, T.L., 2013. Wave loadings acting on Overtopping BReakwater for Energy Conversion. Any kind of Wave Energy Converter (WEC) requires information on reliability of technology and on time required for the return of the investment (reasonable payback). The structural response is one of the most important parameters to take in to account for a consistent assessment on innovative devices. This paper presents results on wave loading acting on an hybrid WEC named Overtopping BReakwater for Energy Conversion (OBREC). The new design is based on the concept of an integration between a traditional rubble mound breakwater and a front reservoir designed to store the wave overtopping from the incoming wave to produce electricity. 2D hydraulic model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark). The analyses of hydraulic model tests have identified the main shapes assumed by wave surfaces at the breakwater ...

/pdf/wave-loadings-acting-on-overtopping-breakwater-for-energy-4883ym60pt.pdf

Wave loadings acting on Overtopping Breakwater for Energy Conversion

Recent research under PROVERBS has demonstrated that wave impact loads can cause damage or failure of caisson or blockwork breakwaters. Research studies of wave loadings, pulsating or impact, have generally used only 2 - dimensional wave flume experiments, and so most design methods are strongly biased towards 2-d . This paper describes results from 3-dimensional wave basin tests by Universities of Naples, Sheffield, and HR Wallingford in the UK Coastal Research Facility (CRF). The aim of the study was to quantify effects on wave pressures or forces of oblique or short-crested wave conditions on simple vertical or composite breakwaters. This analysis has focussed particularly on wave impact loadings as earlier 2-d tests at Wallingford showed them to be potentially severe for some combinations of foundation level and relative wave conditions. New reduction factors are presented.

/pdf/impact-loadings-on-vertical-walls-in-directional-seas-2n6i26yaow.pdf

N.W.H. Allsop

Papers

Impact loadings on vertical walls in directional seas

Breaking Wave Impact Loads On Vertical Faces