Cylindrical Concrete Hulls Under Hydrostatic Loading

Fourteen hollow concrete cylindrical hulls ranging in length from 8 in. to 128 in. (20.3 to 325.1 cm) and having an outside diameter of 16 in. (40.6 cm), and a wall thickness of 2 in. (5.1 cm) were subjected to hydrostatic loading to determine: (1) the effect of cylinder length-to-outside-diameter ratio (L/D₀) on the implosion pressure and strain behavior; and (2) the distance from the edge of the cylinder in which radial displacement was influenced by the end closure. Test results showed that the ratio of implosion pressure to uniaxial concrete strength P_im/f'c decreased as the L/D₀ ratio increased from 0.5 to 2, and then the P_im/f'c ratio became constant. Thus, an infinitely long cylinder was one having an L/D₀ ratio≤2, the effect of the end closure on the behavior of the cylinder becoming negligible at a distance≤1 diameter from its edge. The average implosion pressure for infinitely long cylinders was approximately 2,500 psi (17.2 N/mm²) or a simulated depth in the ocean of 5,500 ft (approx 1,680 m).