A method for development of design diagrams to ensure structural integrity of slender unreinforced concrete breakwater armour units is presented.
The method is based on experimental data from small scale flume tests as well as impact loading of prototype and small scale units. A prerequisite for this is the development of a method for full scale impact testing of prototype units. The method which produces repeatable results is applicable also for quality assessment of the concrete, and is widely used today.
The theoretical background for the work is the separation of the loads and related stresses into three classes: static, pulsating and impact. In principle each type is described independently, and separately scaled by appropriate scaling laws to prototype sizes.
The complex stress field is characterized by the maximum principal tensile stress acting in defined critical sections. This one-parameter characterization makes it possible to develop simple design diagrams for engineering purposes.
Specific design diagrams for integrity of Dolos armour units with the waist ratio as a variable have been produced.
A universal diagram for the evaluation of fatigue due to quasi-static and impact loading of unreinforced concrete is presented. The diagram is partly based in fatigue impact tests performed with Dolosse.
A formula for hydraulic stability of Dolos armour has been developed. The stability in terms of relative number of displaced units is expressed as the function of the incident sea state, the Dolos waist ratio, the laying density and the number of waves. The uncertainty of the formula is evaluated and related partial coefficients calculated.
Examples of the use of the design diagrams are given. The design diagrams are evaluated by comparison with the observed behaviour of prototype structures.
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