Chapter 15: Precast Concrete Framing Systems

Question 1

What are the differences between precast and sitecast concrete?

Answer 1

Precast is faster and less affected by adverse weather conditions.

Question 2

A concrete slab without ribs or voids that spans between beams or bearing walls. For short spans and minimum slab depth.

Answer 2

Solid slabs

Question 3

Precast concrete slabs are used for:

Answer 3

Floor and roof decks

Question 4

A precast concrete slab element that has internal longitudinal cavities to reduce its self-weight. For intermediate spans.

Answer 4

Hollow-core slabs

Question 5

Are steel forms reused?

Answer 5

Yes - durable, permanent steel forms are reused many times, reducing the formwork costs.

Question 6

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.

Answer 6

Double tees and single tees

Question 7

Which components work better under tension and compression?

Answer 7

Steel: works better under tension.
Concrete: works better under compression.

Question 8

What is the purpose of beams and girders?

Answer 8

Provide support for slabs. The projecting rebars will bond with concrete cast on site.

Question 9

How is a girder different from a beam?

Answer 9

A girder is a horizontal beam that supports other beams. It is a very large beam, especially when built up from smaller elements.

Question 10

A horizontal wood member fastened to a wall or beam to which the ends of joists may be connected.

Answer 10

Ledger

Question 11

What is the purpose of columns and wall panels in precast concrete framing systems?

Answer 11

• Provide support for beams and slabs

- Carry mainly axial loads with little bending force

Question 12

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.

Answer 12

Casting beds

Question 13

A steel plate anchored into the surface of concrete to which another steel element may be welded.

Answer 13

Weld plates

Question 14

In precast concrete, an open grid fabric of carbon fibers bounded with epoxy resin is used as a substitute for WWR.

Answer 14

Carbon fiber reinforcing

Question 15

A block of plastic or synthetic rubber that is used to cushion the point at which one precast concrete element rests upon another

Answer 15

Bearing pads

Question 16

Why are sitecast concrete toppings preferred over precast slabs?

Answer 16

• Greater floor strength and stiffness
• fire resistance
• acoustic isolation
• electrical system integration
• smoother, flatter floor surface

Question 17

Provide one advantage for sitecast concrete over precast concrete.

Answer 17

Sitecast is more cost effective to perform on the site

Question 18

Provide one advantage for precast concrete over sitecast concrete.

Answer 18

Bad weather does not stall precast since it is created indoors

Question 19

What are some of the applications for precast concrete slabs?

Answer 19

Parking structures, warehouses, and plants

Planks, slabs, stairs

Question 20

Columns and wall panels provide support for beams and slabs.

Answer 20

True

Question 21

Precast wall panels may be solid, sandwiched or hollow.

Answer 21

True

Question 22

Other precast concrete elements could be precast concrete stairs.

Answer 22

True

Question 23

Precast elements may also be mixed with sitecast concrete, steel, and masonry systems.

Answer 23

True

Question 24

In the beam-to-beam connections, beams are set on bearing pads on the column corbels.

Answer 24

True