Civil Engineering Reference
In-Depth Information
(4)
In beams, specify bars in single layers only. Use one bar size for reinforcement on one face at a given
span location. In slabs, space reinforcement in whole inches, but not at less than 6-in. spacing.
(5)
Use largest bar sizes possible for the longitudinal reinforcement in columns. Use of larger bars sizes
and fewer bars in other structural members will be restricted by code requirements for development of
reinforcement, limits on maximum spacing, and distribution of flexural reinforcement.
(6)
Use or specify fewest possible bar sizes for a project.
(7)
Stirrups are typically the smaller bar sizes, which usually result in the highest total in-place cost of
reinforcement per ton. For overall economy and to minimize congestion of reinforcement, specify the
largest stirrup bar size (fewest number of stirrups) and the fewest variations in spacing. Stirrups spaced
at the maximum allowable spacing, are usually the most economical.
(8)
When closed stirrups are required for structural integrity, and torsion does not govern the design,
specify two-piece closed types (conforming to ACI 12.13.5) to facilitate placing unless closed stirrups
are required for torsion.
(9)
Fit and clearance of reinforcing bars warrant special attention by the Engineer. At beam-column joints,
arrangement of column bars must provide enough space or spaces to permit passage of beam bars.
Bar details should be properly prepared and reconciled before the bars are fabricated and delivered to
the job site. Member joints are far too important to require indiscriminate adjustments in the field to
facilitate bar placing.
(10)
Use or specify standard reinforcing bar details and practices:
• Standard end hooks (ACI 7.1). Note that the tension development length provisions in ACI 12.5 are
only applicable for standard hooks conforming to ACI 7.1.
• Typical bar bends (see ACI 7.2 and Fig. 6 in Ref. 8.1).
• Standard fabricating tolerances (Fig. 8 in Ref. 8.1). More restrictive tolerances must be indicated by
the Engineer in the Contract Documents.
• Tolerances for placing reinforcing bars (ACI 7.5). More restrictive tolerances must be indicated by
the Engineer in the Contract Documents.
Care must be exercised in specifying more restrictive tolerances for fabricating and placing reinforcing
bars. More restrictive fabricating tolerances are limited by the capabilities of shop fabrication
equipment. Fabricating and placing tolerances must be coordinated. Tolerances for the formwork must
also be considered and coordinated.
(11)
Never permit field welding of crossing reinforcing bars for assembly of reinforcement (“tack” welding,
“spot” welding, etc.). Tie wire will do the job without harm to the bars.
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