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Building Design and Construction Handbook - Merritt - Ventech!

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9.28 SECTION NINE<br />

ample, in earthquake-resistant design <strong>and</strong> construction. The A706/A706M Specification<br />

also includes requirements to enhance ductility <strong>and</strong> bendability. Rebars<br />

conforming to A706/A706M are also intended for welding. Weldability is accomplished<br />

by the specification’s limits or controls on the chemical composition of the<br />

steel. Welding of rebars should conform to the requirements of ‘‘Structural Welding<br />

Code–Reinforcing Steel,’’ ANSI/AWS D1.4.<br />

Billet-steel rebars conforming to ASTM A615/A615M are not produced to meet<br />

weldability requirements. They may be welded, however, by complying with the<br />

requirements in ANSI/AWS D1.4.<br />

Coated rebars, either epoxy-coated or zinc-coated (galvanized), are used where<br />

corrosion protection is desired in reinforced concrete structures. The ACI 318 <strong>Building</strong><br />

Code requires epoxy-coated rebars to conform to ASTM Specifications A775/<br />

A775M or A934/A934M. Zinc-coated (galvanized) rebars are required to conform<br />

to ASTM A767/A767M.<br />

ASTM Specification A955M for stainless steel rebars was published in 1996.<br />

Stainless steel rebars are intended for use in highly-corrosive environments, or in<br />

buildings which require non-magnetic steel reinforcement.<br />

In 1997, ASTM issued Specification A970/A970M for headed reinforcing bars.<br />

A headed rebar consists of a head fastened or connected to one or both ends of a<br />

rebar. The head, which can be a rectangular or round steel plate, is connected to<br />

the rebar by welding or threading. Another type of headed rebar has an integrallyforged<br />

head. The purpose of the head is to provide end anchorage of the rebar in<br />

concrete. Headed rebars can be used advantageously in lieu of bars with st<strong>and</strong>ard<br />

end hooks thereby relieving congestion of reinforcement <strong>and</strong> enhancing constructability.<br />

9.23 WELDED-WIRE FABRIC (WWF)<br />

Welded-wire fabric is an orthogonal grid made with two kinds of cold-drawn wire:<br />

plain or deformed. The wires can be spaced in each direction of the grid as desired,<br />

but for buildings, usually at 12 in maximum. Sizes of wires available in each type,<br />

with st<strong>and</strong>ard <strong>and</strong> former designations, are shown in Table 9.6.<br />

Welded-wire fabric usually is designated WWF on drawings. Sizes of WWF are<br />

designated by spacing followed by wire sizes; for example, WWF 6 � 12, W12/<br />

W8, which indicates plain wires, size W12, spaced at 6 in, <strong>and</strong> size W8, spaced at<br />

12 in. WWF 6 � 12, D-12/D-8 indicated deformed wires of the same nominal size<br />

<strong>and</strong> spacing.<br />

All WWF can be designed for Grade 60 material. Wire <strong>and</strong> welded-wire fabric<br />

are produced to conform with the following ASTM st<strong>and</strong>ard specifications:<br />

ASTM A82, Plain Wire<br />

ASTM A496, Deformed Wire<br />

ASTM A185, Plain Wire, WWF<br />

ASTM A497, Deformed Wire, WWF<br />

Epoxy-coated wire <strong>and</strong> welded wire fabric are covered by the ASTM specification<br />

A884/A884M. Applications of epoxy-coated wire <strong>and</strong> WWF include use as<br />

corrosion-protection systems in reinforced concrete structures <strong>and</strong> reinforcement in<br />

reinforced-earth construction, such as mechanically-stabilized embankments.

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