Chapter 22
Steel reinforcement in concrete elements that are permanently exposed to the earth such as in footings must have a minimum concrete cover of
3 inches
the strength of concrete is a residential concrete slab on ground is generally
3000 psi
Hooks in bars are produced by turning the bars through
90 or 180 degrees
Stirrups are generally made of
No 3 or No 4 bars
the term flying form refers to
a large formwork asembly for floor and roof slabs
the tendons used for prestressing PT concrete slab on ground generally consists of
a single 1/2 inch diameter seven wired strand
In a typical sitecast reinforced concrete structure the cost of formwork and shores is
approximately equal to the combined cost of concrete and steel
A PT concrete slab on ground must have perimeter and intermediate ribs
false
According to building codes, plain concrete (concrete without steel reinforcement) is not permitted in new construction.
false
Restoring concrete structures is necessary where excessive deflection of floor slabs or foundation settlement is anticipated on removal of shores
false
The structural design of formwork design is the responsibility of the
general contractor
High density overlay HDO on form plywood
improves the stripability of forms, allows easier cleaning of forms and increases usability of forms
In a site cast concrete construction shores are used
in elevated concrete slabs
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
Height adjustability in shores made of dimension lumber is provided through
lapped members clamped together with spcially made clamps or a screw based metal assembly
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
An isolated concrete slab on ground is generally
none of the above
Concrete shell roofs are not commonly used because
none of the above
Hooks are used
none of the above
The yield strength of prestressing steel is
none of the above
The chairs are used to support reinforcing steel bars are generally
plastic chairs and steel chairs with plastic coated feet
Formwork for a concrete wall generally consists of
plywood form ties walers and stiffbacks fastened together with clamps
Which of the following statements is true
pretensioning is generally done at the precasters plant and yields a precast prestressed concrete member
The most important reason for providing ties in a concrete column is to
prevent the buckling of longitudinal column bars
Form liners are used to
produce textured concrete surfaces
A doubly reinforced beam is one in which
reinforcing bars are provided at the top and bottom of the beam
Scaffold type shores are generally made of
steel pipes
which of the following statements is true
the term tendons includes strands
the most important reason for providing ties in a concrete wall is to
ties are generally not provided in a concrete wall
Stirrups are used in a concrete beam
to increase the shear strength of the beam beyond that provided by concrete
A construction joint in a concrete slab on ground is required if the concrete in the slab cannot be palced in one continuous operation
true
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 comprehensive strength of concrete elements.
true
The term prestressed concrete refers to both pretensioned and posttensioned concrete
true
A capor retarder is required under
under some interior concrete slabs on ground
Mechanical couplers are used
where lap splicing of bars will produce excessive congestion
