Chapter 22 Flashcards
According to building codes, plain concrete is not permitted in new construction. True or false?
False
The term prestressed concrete refers to both pretensioned and postenstioned concrete. True or false?
True
Which of the following is true?
a. The term strands includes tendons
b. the term tendons includes strands
c. none of the above
The term tendons includes strands
Pretensioning is generally done at the precaster’s plant and yields a precast, prestressed concrete member. True or false?
True. Pretensioning is generally done at the precaster’s plant and yields a precast, prestressed concrete member.
In a typical site-cast reinforced-concrete structure, the cost of formwork and shores is:
a. approximately equal to the combined cost of concrete and steel
b. approximately 75% of the combined cost of concrete and steel
c. approximately 50% of the combined cost of concrete and steel.
a. approximately equal to the combined cost of concrete and steel
In site-cast concrete construction, shores are used in?
elevated concrete slabs
High adjustability in shores made of dimension lumber:
a. is provided through lapped members together with specially made clamps
b. is provided through a screw-based metal assembly
c. is provided through a and b
d. is not provided.
C. is provided through a and b
Scaffold type shores are generally made from what material?
Steel pipes
High density overlay (HDO) on form plywood:
a. improves strippability of forms
b. allows easier cleaning of forms
c. increases reusability of forms
d. all of the above
d. all of the above
Aluminum is commonly used as form and shore material because
its strength to weight ratio is high, which reduces the weight of forms and shores
The term flying form refers to ?
a large formwork assembly for floor and roof slabs
Reshoring concrete structures are necessary where excessive deflection of floor slabs or foundation settlement is anticipated on removal of shores. True or False?
False
The structural design of formwork design is the responsibility of who?
The general contractor
Form liners are used to?
produce textured concrete surfaces
The primary purpose of steel reinforcement is to increase the tensile strength of concrete elements. However, steel reinforcement is also used to increase the shear strength and compressive strength of concrete elements. True or false?
True
Stirrups are used in a concrete beam to?
to increase the shear strength of the beam beyond that provided by concrete
Stirrups are generally made of No. ___ and No.___
No. 3 or No.4 bars
A doubly reinforced beam is one in which
Reinforced bars are provided at the top and bottom of the beam
Mechanical couplers are used where?
Where lap splicing of reinforcing bars will produce excessive congestion
Hooks are used:
a. to lap splice reinforcing bars
b. where the lap-splice length is excessive
c. where lap splicing of bars will produce excessive congestion
d. all of the above
e. none of the above
None of the above
Hooks in bars are produced by turning the bars through what degrees?
90 and 180
Steel reinforcement in concrete elements that are permanently exposed to the earth, such as in footings, must have a minimum concrete cover of how many inches?
3in.
The chairs used to support reinforcing steel bars are generally:
a. plastic chairs
b. steel-encased plastic chairs
c. steel chairs with plastic-coated feet
d. a and b
e. a and c
e. a and c
The most important reason for providing ties in a concrete column is to?
Prevent the buckling of longitudinal column bars
The most important reason for providing ties in a concrete wall is to:
a. prevent buckling of longitudinal bars in the wall
b. increase the compressive strength of the wall
c. increase the shear strength of the wall.
d. ties are generally not provided in a concrete wall
d. ties are generally not provided in a concrete wall
Formwork for a concrete wall generally consist of?
Plywood with ties, walers, and stiffbacks fastened together with clamps
A vapor retarder is required under?
some interior concrete slabs on ground
The strength of concrete in a residential concrete slab on ground is generally what psi?
3,000psi
A construction joint in a concrete slab on ground is required if the concrete slab cannot be placed in one continuous operation. True or false?
True
The tendons used for prestressing a PT concrete slab on ground generally consists of what?
A single 1/2in diameter, 7 wire strand
In a PT concrete slab on ground, the tendons are stressed from the ?
Live ends
Pocket formers in a PT concrete slab on ground are used at
Live ends
A PT concrete slab on ground may either be a ribbed slab or a constant thickness slab. true or false?
True
