Chapter 3 

 HISTORICAL DAMAGE MEASUREMENT AND DESCRIPTION 



3.1 Damage Modeling Standards 



There is a substantial amount of literature concerning the measurement of 

 damage on rubble-mound coastal structures. Hughes (1993) reviewed laboratory 

 techniques for measuring damage. He noted three types of experiments for accumulated 

 damage: (a) long-duration tests, (b) accumulated-storm-impacts tests, and (c) residual- 

 stability tests. There is overlap among these three and few standards appear to exist for 

 these types of laboratory studies. Jensen (1984) noted that model storm duration should 

 generally be specified to provide the equivalent of 8 to 10 hr prototype. This is 

 sufficient if equilibrium damage, where further waves cause no additional damage, 

 occurs in this time; but if not, a subset of tests should be conducted to determine the 

 ultimate damage level. Hughes stated that tests should be repeated at least two to four 

 times to develop sufficient statistical certainty in the expected outcome with more 

 extensive testing performed if the variance is large. 



There are two dominant methods for damage measurement: (a) visual: 

 counting the number of individual armor units that have been dislodged and moved 

 more than one nominal diameter from their original location and (b) profile 



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