Chapter 15: Precast Concrete Framing Systems Flashcards
What are the differences between precast and sitecast concrete?
Precast is faster and less affected by adverse weather conditions.
A concrete slab without ribs or voids that spans between beams or bearing walls. For short spans and minimum slab depth.
Solid slabs
Precast concrete slabs are used for:
Floor and roof decks
A precast concrete slab element that has internal longitudinal cavities to reduce its self-weight. For intermediate spans.
Hollow-core slabs
Are steel forms reused?
Yes - durable, permanent steel forms are reused many times, reducing the formwork costs.
A precast concrete slab element that resembles the letters TT in cross section and carries a heavier load. For long spans.
A precast slab element whose profile resembles the letter T. It has the longest span and runs the deepest.
Double tees and single tees
Which components work better under tension and compression?
Steel: works better under tension.
Concrete: works better under compression.
What is the purpose of beams and girders?
Provide support for slabs. The projecting rebars will bond with concrete cast on site.
How is a girder different from a beam?
A girder is a horizontal beam that supports other beams. It is a very large beam, especially when built up from smaller elements.
A horizontal wood member fastened to a wall or beam to which the ends of joists may be connected.
Ledger
What is the purpose of columns and wall panels in precast concrete framing systems?
- Provide support for beams and slabs
- Carry mainly axial loads with little bending force
A permanent, fixed form I which precast concrete elements are produced. They average 400 feet in length, but may extend 800+ feet in some plants.
Casting beds
A steel plate anchored into the surface of concrete to which another steel element may be welded.
Weld plates
In precast concrete, an open grid fabric of carbon fibers bounded with epoxy resin is used as a substitute for WWR.
Carbon fiber reinforcing
A block of plastic or synthetic rubber that is used to cushion the point at which one precast concrete element rests upon another
Bearing pads
Why are sitecast concrete toppings preferred over precast slabs?
- Greater floor strength and stiffness
- fire resistance
- acoustic isolation
- electrical system integration
- smoother, flatter floor surface
Provide one advantage for sitecast concrete over precast concrete.
Sitecast is more cost effective to perform on the site
Provide one advantage for precast concrete over sitecast concrete.
Bad weather does not stall precast since it is created indoors
What are some of the applications for precast concrete slabs?
Parking structures, warehouses, and plants
Planks, slabs, stairs
Columns and wall panels provide support for beams and slabs.
True
Precast wall panels may be solid, sandwiched or hollow.
True
Other precast concrete elements could be precast concrete stairs.
True
Precast elements may also be mixed with sitecast concrete, steel, and masonry systems.
True
In the beam-to-beam connections, beams are set on bearing pads on the column corbels.
True
