structural instrumentation reduces the scaling requirements to a manageable 

 level. The only material properties that must be modeled for measurement of 

 static and wave- induced responses using this technique are density and surface 

 friction. The gross structural response in the form of moments is read 

 directly from the calibrated load cell. The Crescent City dolos design pro- 

 cedure therefore includes measurement of dolos static and pulsating structural 

 response in the physical model using the load cell instrumentation. 



83. Scaling of the hydrodynamic response of armor units where inertial 

 and gravity forces predominate generally follows the Froude law (Hudson 1958) . 

 Wave forces on armor units include buoyancy, drag, inertia, and kinetic or 

 wave-slamming components (Melby 1987) . For waves that approach and exceed 

 their limiting steepness, the kinetic or wave slamming and inertial forces on 

 armor units in the splash zone begin to be dominant (McDougal, Melby, and 

 Tedesco 1987). Froude similitude will, in general, be conservative in these 

 conditions. Froude scaling for structural response in these conditions will 

 also, in general, be conservative. 



84. In the small-scale physical model, load cell technology will be 

 utilized to measure structural response to static, pulsating, and impact 

 loads. Use of the load cell is described in Markle (1990b) and Howell, Rhee , 

 and Rosati (1990) . Burcharth and Howell (1988) describe some general stress 

 measurement and analysis techniques. Measuring and analyzing the static 

 response can be done using the methods outlined in Melby, Rosson, and Tedesco 

 (1990). Static, pulsating, and impact responses can all be measured simul- 

 taneously and extracted from each time series using the following techniques. 

 The individual response EPFs can be combined to form a joint EPF in the final 

 design phase. 



85. The method currently used to extract the static, pulsating, and 

 impact stresses from a single stress record is reasonably simple. The static 

 stresses can be obtained as the mean of each detrended time series, provided 

 the response is fairly symmetric about this mean value. 



86. The impact response can be observed as spikes in the time series 

 and can be removed using a spike removal technique. Note that a very high 

 sampling rate is required to obtain the entire impact response. Also, the 

 model dolos impact response will be distorted due to the inclusion of struc- 

 tural instrumentation and incorrect scaling of material elasticity. Care must 

 be taken in interpreting the model impact results. A scaling factor that 



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