A structural detail survey of twelve families on fifty different ships is summarized in this paper. Seven ship types were surveyed to determine whether or not predicted failures actually occurred.
The families surveyed were beam brackets, tripping brackets, non-tight collars, tight collars, gunwale connections, knife edge crossings, miscellaneous cutouts, clearance cuts deck cutouts, stanchion ends, stiffener ends, and panel stiffeners. Fifty-six groups evolved with a total of 553 observed Variations in structural configuration. The data were synthesized by family groups.
During the survey 490,210 details with 3,307 failures were observed. Eighty-two percent of the failures were in the cargo space and were predominately located in structure adjacent to the side shell. The remaining 18 % were distributed, 10 % forward and 8 % aft of the cargo spaces.
The selection, design and fabrication of structural details are of primary importance in the performance of multi-member structures. Many of these details are used throughout the construction industry; others are used by particular areas such as the marine industry. Structural details include the method of joining two or more structural members together and the miscellaneous structural parts such as flat bars, chocks, angles, and tees used to ensure the performance of the members joined together. Even holes cut for access, construction, pipes, ventilation, waterways and wireways become critical structural details. Those used in the marine industry take many shapes and perform many functions. Their final configurations are numerous and generally left to the discretion of the draftsman or designer. In the past, feedback data on the operational performance of particular structural details has not been available to the marine designer. This invariably raised the question "How do these structural details used in the construction of complex structures actually perform in service?"
The role of the structural detail and the answer to the above question are now being addressed by the Ship Structure Committee. In 1974 it awarded Project No. SR-2l6 "to conduct a state of the art study of shipbuilding structural design details to evaluate and determine design and constructional methods currently in use, and to recommend improved and optional methods." In his preface to Reference 1, Rear Admiral W. M. Benkert of the U.S. Coast Guard and Chairman of the Ship Structure Committee states, "The fabrication of structural design details represents a significant part of shipbuilding costs. These details also represent potential sources of premature failure, fatigue cracking, and brittle fracture. At present, a unifying rationale for design details that includes consideration of reliability and maintainability is not available." In August, 1975, the Ship structure Committee awarded Project No. SR-233, "Structural Tolerance Survey". On January 9, 1976, it awarded Project No. SR-232 "Structural Detail Failure Survey" to Newport News Shipbuilding.
The final report2 of Project SR-232, funded by the Naval Sea Systems Command, Code: SEA 0242, under the advisorship of the National Academy of Sciences Research Committee, is summarized in this Paper.
