This study was conducted in support of the Defense Civil Preparedness Agency's (DCPA) Crisis Relocation Planning (CRP) program in which existing structures will be upgraded to provide fallout shelters for a relocated population. A demonstration test was conducted in which a residential dwelling was upgraded by placing soil against the walls and on the roof of the structure. The shelter was large enough to house 80 people. Upgrading was accomplished partially by hand labor and machinery. The test showed that a conventional structure could be upgraded and that the shelter occupants using tools and materials found in most homes could if necessary upgrade their shelter during the expected 2- or 3-day period of crisis relocation preceding a nuclear attack.

This project concerned expedient upgrading of existing basements to provide some degree of protection against combined nuclear weapons effects, especially air blast; such shelter would be for critical workers remaining in risk areas during a crisis period. In this report, 'expedient' upgrading is that which can be accomplished within about a 24- to 48-hr warning period using indigenous labor and materials, and 'basements' are those that have at most small portion of any side exposed to blast or -- in terms of a partially buried basement -- perhaps no more than the upper 30% or so of any wall(s) exposed. Research, case studies, and this study clearly demonstrate a total lack of any correlation between floor design live load and mean blast collapse overpressure of a floor system. Important is the way the structure is put together and how the R/C designer chose to detail the reinforcing steel. Thus for expedient blast upgrading, availability of a set of 'as-built' drawings is very important (for engineered upgrading, such a set is vital). With drawings available, some conclusions can be reached from engineering experience and existing structures evaluation techniques and ideas developed, to exploit any inherent blast resistance or to enhance it. General schemes for such strengthening are presented (not to scale) and one scheme includes an example in terms of blast resistance.