RDT&E PLAN - 1970 AND BEYOND 
Near-term RDT&E efforts are identified, based on concept alter- 
natives suggested by this study. The program described is intended to 
supply much of the data needed to determine the most desirable MOBS 
configuration, construction method, and choice of materials. 
Structural/Materials Investigation 
Structural investigations should be directed towards: (1) opti- 
mizing elements! shape and size and determining the maximum practical 
size and weight of buoyant support and deck structural elements for 
all stages of fabrication and assembly, from precasting of structural 
units, to launching of modules, to at-sea assembly, and (2) analyzing 
intersection of elements, in particular the column-to-hull and column- 
to-deck connections. 
Regarding item (2) above, certain candidate configurations, e. g., 
the semi-submersible and elevated platforms, have a number of large 
diameter concrete elements which intersect with the deck and/or with 
submerged cylindrical pontoons. More information is needed regarding 
the stress distribution at these major intersections. Particularly 
significant for the semi-submersible concept is determining the optimum 
arrangement for effecting a minimum stress connection between the 
vertical and horizontal buoyant elements. 
Materials Investigation. Findings from the present study suggest 
that significant material and cost savings are possible through the 
use of precast, prestressed structural elements. Such structural units, 
though, have not been used extensively in floating marine structures. 
Future investigations would concentrate on: (1) configuring structural 
elements of ordinary and lightweight concrete, (2) protective measures 
to arrest degradation of prestressing wires and cables and/or use of 
non-corroding metals and alloys for prestressing cables, and (3) com- 
patibility of dissimilar materials in structural configurations under 
cyclic loads, e. g., modules constructed of combined lightweight concrete 
elements with ordinary concrete elements under repeated loading. 
Maintenance of ocean structures can be optimized only if it is 
treated as a basic consideration during design, integrated with functional, 
structural and habitability requirements. Structural geometry and choice 
of materials may depend more on maintenance requirements than the others. 
At-Sea Assembly. An operational analysis considering such functions 
as transporting, towing, positioning and connecting modules or sections 
is critical. Motions of the platform segments together with work barges 
need be considered. Consideration should include assembly in CONUS 
and at remote locations. Methods of assemblying and connecting modules/ 
sections into platforms must be developed. 
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