Precast and Prestressed Concrete PDF

precast is created outside also called as pre-fab or pre-made minimum thickness for precast slabs solid flat slabs- 4inch/100mm to 8inch/205mm hallow core- 6inch/150mm to 12inch/305mm single tees- 20 inchs/ 510mm to 48inch/1220mm double tees- 12inch/30 precast slabs  precast tee...

precast is created outside also called as pre-fab or pre-made minimum thickness for precast slabs solid flat slabs- 4inch/100mm to 8inch/205mm hallow core- 6inch/150mm to 12inch/305mm single tees- 20 inchs/ 510mm to 48inch/1220mm double tees- 12inch/30 precast slabs  precast tees-a pre-stressed concrete product used for parking structures, roofs and floors, where long spans are required and/or heavy loads must be supported.  walls- could be load bearing structures must be able to withstand lateral loadings exterior walls should protect from outside forces doors and windows could withstand vertical loads concrete and masonry walls are more enforcing to withstand forces wall surfaces are exposed  dowels are alternating. concrete surfacing sandblasted plywood-are achived with plywood for  these surfaces are achieve when form works are removed eleminates the need for onsite panel extra reinforcement are needed for transportatio  these are casted on site roof system: use to shed rain and snow should be uv/ radiation resistant PRINCIPLES AND APPLICATIO pre-stressing steel/concret tension cracks comes from center botto compression concrete is good for the compressive strengt compression in steel is good for tensile strengt  bottom part of the beam is always supporte it is measured 1/  metals should follow the British standard inside wire 2% larger large than the outer wir indented bars/wires- are defrmed bar  pre-tension- fixed wire is streched with hydrolic jack. 28n per mm2 overnigh after 24h the hydraulic will be release transfer length-80 to 120 m of wire post-tension- after concrete hardens that is where they do tensionin common applications deep excavation ground anchor injection anchors- hole is bore in the soi if the span is long size pre-stress is more economical for longer spanning concret developed by four swiss engineer 2 basic systems