Evaluation of Expedient Techniques for Strengthening Floor Joist Systems in Residential Dwellings.

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 34-inch plywood and two sheets of 4- by 8-foot by 14-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 1-12-inch by 16-foot by 18-inch steel strap nailed to the bottom of the joists, 2 4- by 8-foot by 14-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 1-12-inch by 16-foot by 18-inch steel strap, and 5 22-gage galvanized steel strap nailed to the bottom of the joists.