This paper discusses the structural design of a breakwater ut1lizing steel bearing piles, concrete deck and concrete front wall.

To substantiate the design criteria, extensive model testing was performed with irregular waves simulating prototype wave energy spector. From the test it appeared that total forces over a limited length of breakwater, due to breaking waves, could be higher than those of the preliminary calculations based on theory. However, for a 100 meter long rigid "unit of breakwater, a reduction of at least 20% in the total forces due to spreading in time of local peak forces, was obtained from 3-dimensional tests. The influence of structural response was studied with the aid of an electronic analogue of the linear mass sprine system.

The model test showed that the configuration of the sea bottom, hence the width of scour protection affects the wave pressures on the breakwater. The experiments showed that this also holds for the overtopping rates, measured with two parapet shapes.

The resulting design showed that utilizing a batter pile type structure solution can be successfully employed as a breakwater construct ion in relatively deep water, where the conventional types of construction, due to the poor soils condition, would have been uneconomical.


The township of Manfredonia is located on the Adriatic coast of Italy, north of Bari. '.the existing port of Manfredonia has very limited waterdepth. As a result of the new industrial expansion in the area, it was decided that the port facilities should be extended to be able to receive vessels up to 25,000 DWT carrying general cargo, bulk cargo and petroleum products. For ships of this size a minimum water depth of 11 m is required. Since the existing port could not be extended to accommodate these vessels due to the limited water depth available, the new port had to be located approximately 2 km offshore.

Due to the type of cargo to be handled, the port had to be protected from the seas. Detailed investigation of the sea and meteorological conditions was carried out to establish the extent of the protection required and the configuration of the new port. The requirements for initial throughputs dictated that the first phase of the development shallhave five berths. Allowance was made for construction of additional berths in the future.

In this paper no attempt was made to give a detailed account of the studies carried out and how the final configuration was established. A detailed description of the design -of the breakwater with special emphasis on the model testing, however., was presented.


At the commencement of the preliminary engineering, since no information was available on the existing soils condition a, the study of the breakwater was concentrated on the use of conventional type of construction.

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