Post Tensioned Roof

Ducts thin sheet metal pipes with claw coupling or welded overlapped seam supplied in lengths of 5 and 6 m.
Post tensioned roof. Post tensioning of foundations transfer beams and plates post tensioned masonry and the combination of precast elements with cast in place concrete by means of post tensioning offer other interesting opportunities. A continuous wire strand in a greased plastic sheath is laid in a circular pattern within the fresh concrete of both the roof and floor panels at the time of casting. To produce an r value of 24 the 7 inch thick concrete roof was cast in place over a 3 inch thick layer of expanded polystyrene. Instead of being stressed to the normal 140 to 150 psi the school roof was post tensioned to 280 to 300 psi.
After only 10 years of service the roof of a 15 million gallon reservoir in greeley colorado was near collapse. Post tensioned slabs use high strength tensioned steel strands to compress the slabs keeping the majority of the concrete in compression. A post tensioning tendon is made up of one. The concrete had been exposed to colorado s extreme temperature cycles and subjected to repeated volume changes and freeze thaw cycles.
The polystyrene was prefabricated in panels with 5 8 inch thick gypsum wallboard glued to the underside. The reservoir was originally designed and built as a partially buried tank with an exposed post tensioned concrete roof. Tendons the basic element of a post tensioning system is called a tendon. Post tensioning is used to enable the floor and roof to achieve a level of water tightness and strength superior to that of regular precast concrete.