Placing Reinforcing Bars, Recommended Practices Flashcards
(29 cards)
What are standard reinforcing bars called?
Deformed bars
Why are reinforcing bars deformed?
To aid in the concrete adhering to the steel.
How is the size of a deformed bar indicated?
By a bar number showing size in eighths of an inch. (e.g., #5 bar = 5/8 inch).
How many standard bar sizes exist?
3 to #11 inclusive, plus #14 and #18 (11 Total)
What four things must ASTM bar identification include?
1) Producer’s mill
2) Size of the bar
3) Type of steel
4) Grade
What is the purpose of reinforcing steel?
To increase tensile strength in concrete.
Where should reinforcing steel be placed in a beam?
Near the bottom to resist tensile forces.
What happens if top bars are lowered or bottom bars raised by ½ inch in a 6” slab?
The slab’s load capacity could be reduced by 20%.
Is exact positioning of longitudinal bars always critical?
No, it is generally not critical to member strength.
What tolerances are applied to bar spacing?
Tolerances in spacing apply in walls and solid slabs.
What is the minimum concrete cover for footings cast against earth?
3 inches
Where should 3” cover be provided when concrete is cast against ground?
At sides and bottoms of footings or structural members placed on ground.
How is bar lapping/splicing often designated?
In bar diameters (e.g., 40d).
What is the minimum splice length for reinforcing bars?
12 inches or 25x the diameter of the larger bar, whichever is greater.
Where is a Snap or Single Tie typically used?
In flat horizontal work.
When is a Wrap and Snap Tie used?
When tying wall reinforcement to hold bars during construction.
When is a Saddle or U Tie used?
For tying footing bars or securing column ties to vertical bars.
What ties can secure heavy mats lifted by crane?
Wrap and Saddle Tie.
Where is a Figure Eight Tie used?
In walls instead of Wrap and Snap Tie.
What is a Nailhead Tie used for?
When nails are used to hold bars away from forms.
Is it necessary to tie every bar intersection?
No. Tying adds no strength to the finished structure.
What is sufficient for bar tying?
Tie at every 4th or 5th intersection.
What is the purpose of welded wire fabric in slabs?
To hold cracks together.
Does welded wire fabric reinforce concrete slabs?
No, it does not provide reinforcement.
