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## Fire Damage to Wooden Structural Members The failure of wooden bowstring trusses alone has been responsible for dozens of firefighter deaths, including: * Hackensack, NJ, Ford dealership in 1988. * Waldbaum's Supermarket in Brooklyn, NY, in 1978. * A bowling alley in Richfield Park, NJ, in 1967...

## Fire Damage to Wooden Structural Members The failure of wooden bowstring trusses alone has been responsible for dozens of firefighter deaths, including: * Hackensack, NJ, Ford dealership in 1988. * Waldbaum's Supermarket in Brooklyn, NY, in 1978. * A bowling alley in Richfield Park, NJ, in 1967. Add to this the number of roof and floor failures due to burn-through, and the danger is tremendous. Remember, wooden structural elements burn through at a rate of about 1 inch for every 45 minutes of open-burning time. If fire can attack two sides of a joist, for example, the standard 1/2-in.-wide (2x8) joist will burn completely through in less than 45 minutes and will have lost its load-carrying ability long before that. ## The Heating of Unprotected Steel Like wood, steel is affected by heat. Lightweight steel-bar joists can lose their strength in as little as 5-10 minutes of fire exposure. Thicker pieces of steel take a longer time to heat up, but when they reach 1500°F, their failure is just as assured. Fortunately, steel sags prior to total failure. This may provide sufficient warning to firefighters working on a steel deck, but it may not be visible to people working below it due to smoke obscuring their view. One particularly dangerous situation involving unprotected steel occurs in columns fabricated from pipe and steel plate. In this case, the columns are made from pipe cut to the desired length and welding two pieces of steel plate to the ends. This results in a sealed chamber that can rupture with explosive violence when heated during a fire. This failure will suddenly bring down whatever it supports, including floors, roofs, and walls. One of the most potentially dangerous situations can occur when these columns support a girder that has been installed when renovating two older buildings into a single occupancy. In this case, the bearing walls of the original structures are cut away on the first floor only, where a new girder is inserted. This girder will carry the weight of the remaining walls and floors that are left intact on the upper floors. There is a tremendous amount of weight that now rests on unprotected steel Lally columns on the first floor. If these columns reach just 800°F, they should be expected to fail, bringing down the entire upper floors.