300 

 200 



100 



50 



20 



10 



^- 5% 



THIS STUDY, D / d =0.2 - 0.4 



/ / 

 / / 

 / / 

 / / 

 / / 



/ / 

 / / 



/ 4 V>2.t8jJ 



/ 



«A/ 

 / A< A25" A'5 

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A2 



;;;->;;/;;;;;;////; /-ry/^y- 



CERC 



A15 



AV, 



CERC OATA, D/ d =0.3 



0'234 

 Ratio of Wavelength-to-Breakwater Width, L/W 



Figure 90. Comparison of prototype- and model-scale force parameter, F/yW 2 , 

 as a function of relative breakwater width, L/W, Goodyear Tire 

 and Rubber Company scrap-tire floating breakwater (after Harms, 

 1979a). 



3. Wave-Guard Scrap-Tire Floating Breakwater Concept . 



Harms and Bender (1978) developed and tested a scrap-tire floating 

 breakwater which differs principally from other scrap-tire concepts in terms 

 of tire arrangement (spatial tire density) and rigidity. This concept, called 

 the "Wave-Guard" (also referred to as the "Pipe-Tire" structure), was 

 experimentally tested at model scale. The structural component of the Wave- 

 Guard is constructed with massive logs (telephone poles, steel beams, 

 reinforced concrete beams, etc.). Strips of conveyor belting are used to 

 connect one beam to another, and to thread the scrap tires. The tire strings 

 are closely spaced (Fig. 91) so that the spatial density (number of tires per 

 unit volume of breakwater) is relatively high, which results in a tightly 

 packed structure. A significantly smaller structure in planform area is 

 required to attain the same wave attenuation performance. 



a. Wave Attenuation Effectiveness. Harms and Bender (1978) compared the 

 performance of the Wave-Guard and the Goodyear Tire and Rubber Company concept 

 for the same wave characteristics. Wave transmission design curves were 

 generated, and it was determined that the Wave-Guard offers a significantly 

 greater degree of wave attenuation than the Goodyear concept. This was 

 attributed to the greater rigidity of the Wave-Guard, and to the fact that it 

 is much less porous than the Goodyear structure. The results of the 

 comparison are presented in Figure 92. 



137 



