Giovanni Cuomo

Dynamic Wave Loads on Coastal Structures: Analysis of Impulsive and Pulsating Wave Loads

It is accepted that dynamic loads and structural responses must be analysed in design of large offshore structures. Recent studies in Europe and Japan have shown that it is unsafe to ignore high intensity short duration loads in design of caisson breakwaters and related harbour structures. Dynamic effects of wave loads are however seldom included in structural analysis of coastal structures, leading to designers ignoring short-duration wave loads, perhaps contributing to damage to a range of breakwaters, seawalls or suspended decks. This paper reports recent advances in knowledge on impulsive wave loads, describes analysis for dynamic responses, and illustrates a range of prediction methods to include these important effects in design. It compares measurements of impulsive and pulsating loads from physical models of coastal structures, to quantify their magnitude and relative importance.

Physical Model Studies of Wave-Induced Loading on Exposed Jetties: Towards New Prediction Formulae

Within a research project on “Exposed Jetties”, a series of physical model studies has measured wave-induced loading on a model of an open-piled jetty structure. These measurements gave a series of force and pressure data on selected structural elements of the model jetty, covering a wide range of wave conditions and deck geometries. Initial analysis of these new data revealed inconsistencies and gaps in methods previously used to predict wave-induced loading on jetty structures and provided the basis for new guidance for their hydraulic design. A series of dimensionless variables has been found for horizontal and vertical forces (and pressures) on beam elements and deck slabs. Dimensionless relationships are presented for selected configurations and structure elements to provide consistent engineering guidance for wave loading on exposed (open piled) jetties.

WAVE LOADING, OVERTOPPING AND TRANSMISSION OF LOW CREST CAISSON BREAKWATERS

Recent LNG projects have pointed out the efficiency of low crested caissons breakwaters in providing shelter from waves to LNG terminals during frequent conditions whilst allowing for wave overtopping / transmission during most severe storms, reducing the design loads and therefore the overall cost of the breakwater. Unfortunately, little is known on hydrodynamic behaviour and loading of low crested structures heavily overtopped by long waves and use of existing design codes generally leads to over-design and excessive construction costs. Bearing this in mind, both physical and numerical models have been successfully applied to investigate wave-structure interaction problems and in particular to improve accuracy and increase confidence in the estimations of wave loading, wave overtopping and transmission over low crested structures. Tentative semi-empirical formulas are presented for wave overtopping and wave transmission based on new experimental data.

Hydro-geotechnical stability of rubble mound breakwaters under wave action

Hydro-geotechnical stability of rubble mounds is investigated by means of experimental tests, CFD and FE geotechnical models. Laboratory tests were conducted to investigate flow motion and time-varying pore pressure distribution within a rubble mound breakwater. Data have been used to test the performances of the commercial CFD tool CFX. Experimental and numerical data on flows / pressures can be coupled with FE geotechnical models to assess liquefaction likelihood and mechanisms of failure of foundation soil of rubble mounds under cyclic wave motion.

Uplift Forces on Pier Deck of Coastal Bridges and the Role of Air

Recent failures of coastal bridges during extreme storm events have focused attention on the need for research on wave loading of coastal structures suspended slightly above the still water level. This paper presents findings from large-scale experimental work carried out in the wave basin. Measurements from physical model tests are used to gain insights on the dynamics of wave-loading of coastal bridges and to derive prediction methods for both quasi-static and impulsive wave loads. The effect of openings in the bridge deck is also discussed, and guidance derived for design purpose.