(6) Design Data (Blumberg and Strader, 1969; Cloyd, 1968). 



(a) Design Conditions. 



Depth at structure, 62 feet at mean low tide. 



Tidal range, 30 feet at mean low tide. 



Maximum depth, 92 feet at mean low tide. 



Design wave, 28 feet at 8.5-second period exerting: 600 pounds per 



square foot at crest, and 200 pounds per square foot at bay bottom. 

 Current loading, 120 pounds per square foot on flat members, and 40 



pounds per square foot on round members. 

 Wind, 40 pounds per square foot on flat members, and 24 



pounds per square foot on round members (based on 65 mUes 



per hour with gusts to 100 miles per hour. 

 Earthquake-loading mass coefficient, 0.10 to 0.15 



(depending on deck loading). 

 Water temperature range, 28° to 46°. 

 Ice-crushing strength, 300 pounds per square foot at 2 feet 



below water surface (based on temperature, thickness, and 



rate of loading). 

 Ice movement from any direction was the governing load, occurring during ice breakup 

 with ice pans up to 10-foot diameter moving back and forth with current. 



(b) Model Study (Cloyd, 1968). Two models of the monopod jacket were 

 constructed. The smaller one was used to evalu'kte towing requirements and stabihty under 

 tow. The tests indicated that the jacket in its towing configuration would have a draft of 

 about 13 feet with its centers of buoyancy and gravity 8 and 47 feet above the jacket's low 

 point. 



The second model, larger and more complex, was constructed to study the jacket 

 characteristics during the critical period of setting. As a result the structure was lowered into 

 one end of the pontoons first and then settled level onto the other end rather than sunk 

 balanced and erect aU the way as originally planned. To take advantage of the best possible 

 sea conditions, the structure was set during a 45-minute slack tide using its own individually 

 controlled anchor system. 



Diving operations were hampered by fast currents, zero visibility, and low temperatures; 

 and floating equipment by the strength of the currents and the directional variation. 



(c) Instrumentation (Geminder, 1968). Underwater strain-gages were placed to 

 determine stresses and strains, to calculate ice force on the structure, and to measure load 

 distribution vrithin the structure. Data on ice forces (the governing factor in the design) are 

 important to evaluate the present criteria and to set criteria for future work. 



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