Expedient techniques for reinforcing wood floor joist systems were evaluated by building 15 test specimens and subjecting them to static tests in a 200-kip loader. Each specimen consisted of three 2- by 10-inch by 16-foot floor joists (16 inches on center). Two sheets of 4- by 8-foot by 3/4-inch plywood and two sheets of 4- by 8-foot by 1/4-inch Masonite were centered and nailed to the joists. A 2- by 10-inch by 4-foot header board was nailed to each end of the floor specimen. Unreinforced and reinforced floor specimens were tested. The expedient techniques of joist reinforcement evaluated were: (1) 1-1/2-inch by 16-foot by 1/8-inch steel strap nailed to the bottom of the joists, (2) 4- by 8-foot by 1/4-inch plywood nailed to the bottom of the joists, (3) U-shaped hanger straps bolted around the joists, (4) combination of the hanger straps and 1-1/2-inch by 16-foot by 1/8-inch steel strap, and (5) 22-gage galvanized steel strap nailed to the bottom of the joists.

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.