Earthquake Resistant Submarine Drydock Block System Design

摘要

This thesis develops a 3-degree of freedom submarine drydock blocking system computer aided design package. Differential equations of motion are developed to take into account high blocking systems, wale shores, and side block cap angles. The computer program is verified by a case study involving the earthquake sliding failure of the USS Leahy (CG-16). A parametric study is conducted to determine the effects of wale shores, isolators, and block stiffness and geometry variations on system survivability. The effects of using earthquake acceleration time histories with differing frequency spectrums on system survivability is studied. None of eleven submarine drydock blocking systems studied survive to dry dock failure (0.26 g's) or even meet the Navy's current 0.2 g survival requirement. This shows that current Navy submarine drydock blocking systems are inadequate to survive expected earthquakes. Two design solutions are found that meet the dry dock failure requirements. The low stiffness solution uses dynamic isolators and rubber caps, and the high stiffness solution uses wale shores and rubber caps. The wale shore solution virtually prevents the submarine from moving horizontally relative to the dock floor. The isolator solution allows relatively large horizontal displacements to occur. Using the wale shore solution, the submarine experiences forces which are an order of magnitude higher than these seen by the isolator solution. Both design solutions can be constructed; however, there are cost and production interference concerns. Theses. (edc)