Today's post was shared by Safe Healthy Workers and comes from www.fireengineering.com
Article and photos by Gregory Havel
Sometimes we get the impression from news stories and even from firefighting textbooks that the truss is a recent development in construction, and that the bowstring truss (photo 1) is the most hazardous in a fire.
A truss is a structural component that is made up of smaller members that are arranged in triangles and connected at their intersections. Individual truss members are either in compression or in tension. Trusses are usually used to span distances that are too long for conventional beams; or, in smaller dimensions, to reduce weight and cost during construction.
The structure in photo 1 was built around 1960, and used the bowstring truss so that there would be a large unobstructed floor area for retail sales and so that the roof would easily shed rain and melting snow. These trusses are usually built of either wood or steel, although some have wood for the top and bottom chords and steel for the web members. Bowstring trusses were originally designed for bridges, but became popular during World War II to support the long roof spans of aircraft hangers and manufacturing facilities.
Sometimes we get the impression from news stories and even from firefighting textbooks that the truss is a recent development in construction, and that the bowstring truss (photo 1) is the most hazardous in a fire.
A truss is a structural component that is made up of smaller members that are arranged in triangles and connected at their intersections. Individual truss members are either in compression or in tension. Trusses are usually used to span distances that are too long for conventional beams; or, in smaller dimensions, to reduce weight and cost during construction.
The structure in photo 1 was built around 1960, and used the bowstring truss so that there would be a large unobstructed floor area for retail sales and so that the roof would easily shed rain and melting snow. These trusses are usually built of either wood or steel, although some have wood for the top and bottom chords and steel for the web members. Bowstring trusses were originally designed for bridges, but became popular during World War II to support the long roof spans of aircraft hangers and manufacturing facilities.
