Precast Concrete

Question 1

precast beam shapes

Answer 1

usually rectangular, T-shaped, or L-shaped.

Question 2

advantage of T and L shaped beams

Answer 2

floor flush w/ top of beam (min. total depth)

Question 3

very efficient, widely used,

topping slab poured, cover joints and level floor.

Answer 3

single T and double T sections

Question 4

typ. rec. shape w welding plates top+bottom.

cast w haunches (shoulders)

Answer 4

Precast Columns

Question 5

in addition to T-section as floor/roof,

simple reinforced slabs used.

Answer 5

Floor and Roof Panels

Question 6

Floor and Roof Panels: solid slab =

Answer 6

light loads + short spans

Question 7

Floor and Roof Panels: hollow, cored slab =

Answer 7

heavier load + longer span

increased depth, while min weight.

Question 8

Floor and Roof Panels: hollow, cored slab can be up to this length

Answer 8

up to 36ft long

6-12” thick, 4’ wide

Question 9

multistory technique,
entire floor sections are cast on ground,
one on top of other,
around pre-erected columns.
bond breaker between successive pours.
lifted into place (jacks attached to columns)
connected to columns w weld plates.
typ min formwork and construction time.

Answer 9

Lift slab construction

Question 10

Wall Panels typ. dims

Answer 10

typ 5-8” thick, long enough to span columns or beams.

Question 11

$ savings @ wall panels

Answer 11

if panels span beams, > $ savings in multistory by panels spanning 2 floors.

Question 12

can be cast horizontally right on floor slab using a bond breaker

Answer 12

tilt-up

Question 13

sheet of plastic or liquid solution (better finish)

Answer 13

bond breaker

Question 14

members have internal stresses applied before subject to service loads.
compressive forces where member would be in tension.
more efficient + economical section,
reduces cracking + deflection,
increases shear strength,
longer spans/ greater loads.

Answer 14

Precast, Prestressed Concrete

Question 15

precasting plant.
high-strength stranded cable/wire draped in forms, tensile force applied.
once cured, cables are cut,
compressive forces transferred to concrete through bond between cable/conc.

Answer 15

Pretensioning

Question 16

hollow sleeves or conduits placed in forms on site.
high-strength steel tendons,
stressed w hydraulic jacks after cure,
ends secured to conc.
in bonded construction: sleeves removed, grout forced between tendons/conc.

Answer 16

Post-tensioning