Wave Induced Foraes and Motions of Tubular Structures 



0.2 0.3 



WAVE HEIGHT, FT 



0.5 



Fig, 6, Surge motion -- Model 1 



Figure 5 contains a comparison of measured and computed 

 tension variations in the mooring legs for three different wave 

 periods and Fig. 6 contains the platform surge motion. Again, the 

 agreement between computed and measured values is about as good 

 as in the case of the single cylinder. Two features should be noted 

 here. First, a mean curve drawn through the experimental tension 

 variations appears to curve slightly concave downward with increas- 

 ing wave height, thus indicating a measurable nonlinearity in this 

 quantity. Second, better agreement between the computed and 

 measured values is obtained for motions than for forces. Note that 

 the motions are shown for two different values of the assumed 

 quadratic drag coefficient. The effect of a substantial change in 

 this quantity is seen to be slight. 



Triangular Platform 2 in Random Waves 



A second triangular platform was tested in both regular and 

 irregular waves. This platform, designated Model 2; was similar in 

 arrangement to the platform depicted in Fig. 3 and had the following 

 characteristics : 



Weight 28.49 lbs 



Buoyancy 32,30 lbs 



Length of side 3.12 ft 



Main horizontal pontoon dia. 0,187 ft 



Vertical cylinder dia. 0.381 ft 



110.5 



