A major oil company proposed a test program on large-scale, 

 thin-walled concrete models. This proposal eventually led to a joint 

 industry-Navy test program carried out at CEL. 



During this period another important test was conducted at CEL on 

 a large thick-walled concrete cylinder structure. The structure, called 

 SEACON 1 , was part of an integrated seafloor engineering experiment to 

 demonstrate capability in constructing operational facilities in the ocean 

 (Ref 9). The structure was built in 1972, placed in the ocean at 600 

 feet (180 meters) for 10 months, and then retrieved. After being on 

 "display" for several years, it was tested to failure in the ocean in 1976 

 to determine its implosion strength . 



Objective 



This report presents updated design guides for implosion of con- 

 crete cylinders . The guides are based on the test results from the 

 thick-walled, SEACON I, cylinder test (Appendix A) and from the 

 thin- walled cylinder tests (Appendix B). The approach to design is 

 similar to that already presented in Reference 8. However, the new 

 data are superior to that presented previously, especially for the thin- 

 walled models. The updated guides for thin-walled cylinders allow such 

 structures to operate at considerably deeper depths than indicated in 

 the past guides . 



Description of Tests 



Thick-Walled Structures . The SEACON I structure was a rein- 

 forced concrete cylindrical hull having hemispherical end closures . The 

 overall structure length was 20 feet (6.1 meters); outside diameter, 

 10.1 feet (3.08 meters); and wall thickness, 9.5 inches (241 mm). 

 Steel reinforcement of 0.7% by area was used in both the hoop and axial 

 directions. At the time of the implosion test the concrete compressive 

 strength was 10,470 psi. 



