1、Section 9 REINFORCING STEEL 9.1 DESCRIPTION the point of shipment to the jobsite shall conform to the requirements of AASHTO M 284 (ASTM D 3963) or ASTM A 934, as specified in the contract documents. Epoxy-coated reinforcing bars shall be coated in a cer- tified epoxy coating applicator plant in acc
2、ordance with the Concrete Reinforcing Steel Institutes Voluntary Cer- This work shall consist of furnishing and placing rein- forcing steel in accordance with these Specifications and in conformity with the plans. 9.2 MATERIAL tification Program for Fusion-Bonded Epoxy Coated Ap- plicator Plants, or
3、 equivalent. Epoxy-coated steel wire and welded wire fabric for re- inforcement shall conform to the requirements of ASTM A 884, Class A. Each shipment of epoxy-coated reinforcing steel shall be accompanied with a Certificate of Compliance signed All reinforcing bars shall be deformed except that pl
4、ain Reinforcing steel shall conform to the requirements of bars may be used for spirals and ties. the following specifications. by the applicator of the coating certifying that the epoxy- coated reinforcing bars conform to the requirements of AASHTO M 284 or ASTM A 934 or that the epoxy- coated wire
5、 or welded wire fabric conforms to ASTM A 884, Class A. 9.2.1 Uncoated Reinforcing Steel Deformed and Plain Billet-Steel Bars for Concrete Re- 31 (ASTM A 615). Grade 60 inforcement-AASHTO shall be used unless otherwise shown or specified. Low-Alloy Steel Deformed and Plain Bars for Con- 9.2.3 Stainl
6、ess Steel Reinforcing Bars Crete Reinforcement-ASTM A 706. Rail-Steel Deformed and Plain Bars for Concrete Re- inforcement-AASHTO M 42 including Supplementary Requirement S1 (ASTM A 616 including Supplementary Requirement Si). Grade 60 steel shall be used unless oth- erwise shown or specified. Defor
7、med Steel Wire for Concrete Reinforcement- AASHTO M 225 (ASTM A 496). Welded Plain Steel Wire Fabric for Concrete Rein- forcement-AASHTO M 55 (ASTM A 185). Plain Steel Wire for Concrete Reinforcement- AASHTO M 32 (ASTM A 82). Welded Deformed Steel Wire Fabric for Concrete Re- inforcement-AASHTO M 22
8、1 (ASTM A 497). When required by the contract documents, deformed or plain stainless steel reinforcing bars shall conform to the requirements of ASTM A 955 M. 9.2.4 Mill Test Reports Whenever steel reinforcing bars, other than bars con- forming to ASTM A 706, are to be spliced by welding or when oth
9、erwise requested, a certified copy of the mill test report showing physical and chemical analysis for each heat or lot of reinforcing bars delivered shall be provided to the Engineer. 9.2.2 Epoxy-Coated Reinforcing Steel 9.3 BAR LISTS AND BENDING DIAGRAMS The reinforcing steel to be epoxy coated sha
10、ll conform to Article 9.2.1. When epoxy coating of reinforcing bars is required, the coating materials and process, the fabrication, handling, identification of the bars, and the repair of damaged coat- ing material that occurs during fabrication and handling to When the plans do not include detaile
11、d bar lists and bending diagrams, the Contractor shall provide such lists and diagrams to the Engineer for review and approval. Fabrication of material shall not begin until such lists have been approved. The approval of bar lists and bending dia- grams shall in no way relieve the Contractor of resp
12、onsi- 549 550 HIGHWAY BRIDGES 9.3 bility for the correctness of such lists and diagrams. Any expense incident to the revision of material furnished in accordance with such lists and diagrams to make it com- ply with the design drawings shall be borne by the Con- tractor. 9.4 FABRICATION 9.4.1 Bendin
13、g Bar reinforcement shall be cut and bent to the shapes shown on the plans. Fabrication tolerances shall be in ac- cordance with AC1 315. All bars shall be bent cold, unless otherwise permitted. Bars partially embedded in concrete shall not be field bent except as shown on the plans or specifically
14、permitted. 9.4.2 Hooks and Bend Dimensions The dimensions of hooks and the diameters of bends measured on the inside of the bar shall be as shown on the plans. When the dimensions of hooks or the diameter of bends are not shown, they shall be in accordance with Di- vision I, Article 8.23 or AC1 318,
15、 “Building Code Re- quirements for Reinforced Concrete.” 9.4.3 Identification Bar reinforcement shall be shipped in standard bundles, tagged and marked in accordance with the Manual of Stan- dard Practice of the Concrete Reinforcing Steel Institute. 9.5 HANDLING, STORING, AND SURFACE CONDITION OF RE
16、INFORCEMENT Steel reinforcement shall be stored above the surface of the ground on platforms, skids, or other supports and shall be protected from mechanical injury and surface de- terioration caused by exposure to conditions producing rust. When placed in the work, reinforcement shall be free from
17、dirt, loose rust or scale, mortar, paint, grease, oil, or other nonmetallic coatings that reduce bond. Epoxy coat- ings of reinforcing steel in accord with standards in this article shall be permitted. Reinforcement shall be free from injurious defects such as cracks and laminations. Bonded rust, su
18、rface seams, surface irregularities, or mill scale will not be cause for rejection, provided the mini- mum dimensions, cross-sectional area, and tensile prop- erties of a hand wire brushed specimen meet the physical requirements for the size and grade of steel specified. Epoxy-coated reinforcing ste
19、el shall be handled and stored by methods that will not damage the epoxy coat- ing. All systems for handling epoxy-coated reinforce- ment bars shall have adequately padded contact areas. All bundling bands shall be padded and all bundles shall be lifted with a strong back, multiple supports, or plat
20、form bridge so as to prevent bar-to-bar abrasion from sags in the bundle. Bars or bundles shall not be dropped or dragged. Epoxy-coated reinforcing steel shall be stored on wooden or padded supports. Epoxy-coated reinforcing steel shall be protected from sunlight, salt spray, and weather exposure. P
21、rovisions shall be made for air circulation around the coated rein- forcement to minimize condensation under the protective covering. 9.6 PLACING AND FASTENING 9.6.1 General Steel reinforcement shall be accurately placed as shown on the plans and firmly held in position during the placing and consol
22、idation of concrete. Bars shall be tied at ail intersections around the perimeter of each mat and at not less than 2-foot centers or at every intersection, whichever is greater, elsewhere. Bundled bars shall be tied together at not more than 6-foot centers. For fasten- ing epoxy-coated reinforcement
23、, tie wire and metal clips shall be plastic-coated or epoxy-coated. If uncoated welded wire fabric is shipped in rolls, it shall be straight- ened into flat sheets before being placed. Welding of crossing bars (tack welding) will not be permitted for as- sembly of reinforcement unless authorized in
24、writing by the Engineer. 9.6.2 Support Systems Reinforcing steel shall be supported in its proper posi- tion by use of precast concrete blocks, wire bar supports, supplementary bars or other approved devices. Such rein- forcement supports or devices shall be of such height and placed at sufficiently
25、 frequent intervals so as to maintain the distance between the reinforcing steel and the formed surface or the top surface of deck slabs within Y4 inch of that indicated on the plans. Platforms for the support of workers and equipment during concrete placement shall be supported directly on the form
26、s and not on the reinforcing steel. 9.6.3 Precast Concrete Blocks Precast concrete blocks shall have a compressive strength not less than that of the concrete in which they 9.6.3 DIVISION II-CONSTRUCTION 55 1 are to be embedded. The face of blocks in contact with forms for exposed surfaces shall not
27、 exceed 2 inches by 2 inches in size and shall have a color and texture that will match the concrete surface. When used on vertical or sloping surfaces, such blocks shall have an embedded wire for securing the block to the reinforcing steel. When used in slabs, either such a tie wire or, when the we
28、ight of the reinforcing steel is sufficient to firmly hold the blocks in place, a groove in the top of the block may be used. For epoxy-coated bars, such tie wires shall be plastic-coated or epoxy-coated. 9.6.4 Wire Bar Supports Wire bar supports, such as ferrous metal chairs and bolsters, shall con
29、form to industry practice as described in the Manual of Standard Practice of the Concrete Re- inforcing Steel Institute. Such chairs or bolsters which bear against the forms for exposed surfaces shall be ei- ther Class l-Maximum Protection (Plastic Protected) or Class 2, Type B-Moderate Protection (
30、Stainless Steel Tipped) for which the stainless steel conforms to ASTM A 493, Type 430. For epoxy-coated reinforcement, all wire bar supports and bar clips shall be plastic-coated or epoxy-coated. 9.6.5 Adjustments Nonprestressed reinforcement used in post-tensioned concrete shall be adjusted or rel
31、ocated during the installa- tion of prestressing ducts or tendons, as required to pro- vide planned clearances to the prestressing tendons, an- chorages and stressing equipment, as approved by the Engineer. 9.6.6 Repair of Damaged Epoxy Coating In addition to the requirements of Article 9.2.2, dam-
32、aged coating on epoxy-coated reinforcing steel that oc- curs during shipment, handling and placement of the re- inforcing steel shall be repaired. The maximum amount of repaired damaged areas shall not exceed 2% of the sur- face area in any linear foot of each bar. Should the amount of damaged coati
33、ng incurred during shipment, handling and placing exceed 2% of the surface area in any linear foot of each bar, that bar shall be removed and replaced with an acceptable epoxy-coated bar. The sum of the areas covered with patching material applied dur- ing repairs at all stages of the work shall not
34、 exceed 5% of the total surface area of any bar. The patching material shall be prequalified as required for the coating material and shall be either identified on the container as meeting the requirements of Annex Al of AASHTO M 284 or Annex Al of ASTM A 934, or shall be accompanied by a Certificat
35、e of Compliance certifying that the material meets the requirements of said Annexes Al. Patching of damaged areas shall be performed in accordance with the patching material manufacturers recommendations. Patches shall be allowed to cure before placing concrete over the coated bars. 9.7 SPLICING OF
36、BARS 9.7.1 General All reinforcement shall be furnished in the full lengths indicated on the plans unless otherwise permitted. Except for splices shown on the plans and lap splices for No. 5 or smaller bars, splicing of bars will not be permitted with- out written approval. Splices shall be staggere
37、d as far as possible. 9.7.2 Lap Splices Lap splices shall be of the lengths shown on the plans. If not shown on the plans, the length of lap splices shall be in accordance with Division I,.Article 8.32, or as ap- proved by the Engineer. In lap splices, the bars shall be placed and tied in such a man
38、ner as to maintain the minimum distance to the sur- face of the concrete shown on the plans. Lap splices shall not be used for Nos. 14 and 18 bars except as provided in Division I. Articles 4.4.1 1.5.7 and 8.32.4.1. 9.7.3 Welded Splices Welded splices of reinforcing bars shall be used only if detail
39、ed on the plans or if authorization is made by the En- gineer in writing. Welding shall conform to the Structural Welding Code, Reinforcing Steel, ANSI AWS D1.4 of the American Welding Society and applicable special provi- sions in the contract documents. Welded splices shall not be used on epoxy-co
40、ated bars. To avoid heating of the coating, no welding shall be per- formed in close proximity to epoxy-coated bars. 9.7.4 Mechanical Splices Mechanical splices shall be used only if preapproved or detailed on the plans or authorized in writing by the En- gineer. Such mechanical splices shall develo
41、p in tension or compression, as required, at least 125% of the specified yield strength of the bars being spliced. When requested by the Engineer, up to two field splices out of each 100, or portion thereof, placed in the 552 HIGHWAY BRIDGES 9.7.4 work and chosen at random by the Engineer, shall be
42、re- moved by the Contractor and tested by the Engineer for compliance to 125% of the specified yield strength of the bars being spliced. 9.8 SPLICING OF WELDED WIRE FABRIC Sheets of welded wire fabric shall be spliced by over- lapping each other sufficiently to maintain a uniform strength and shall
43、be securely fastened at the ends and edges. The edge lap shall not be less than one mesh in width plus 2 inches. 9.9 SUBSTITUTIONS Substitution of different size reinforcing bars will be permitted only when authorized by the Engineer. The sub- stituted bars shall have an area equivalent to the desig
44、n area, or larger, and shall conform to the requirements of Division I, Article 8.16.8.4. 9.10 MEASUREMENT Steel reinforcement incorporated in the concrete will be measured in pounds based on the total computed weight for the sizes and lengths of bars, wire or welded wire fabric shown on the plans o
45、r authorized for use in the work. The weight of bars will be computed using the follow- ing weights: Bar Size Weight lbs. per lin. feet No. 3 0.376 No. 4 0.668 No. 5 1 .O43 No. 6 1 SO2 No. 7 2.044 No. 8 2.670 No. 9 3.400 No. 10 4.303 No. 11 5.313 No. 14 7.65 No. 18 13.60 The weight of wire, welded w
46、ire fabric and plain bars of sizes other than those listed above, will be computed from tables of weights published by CRSI or computed using nominal dimensions and an assumed unit weight of 0.2833-pound per cubic inch. The cross-sectional area of wire in hundredths of square inches will be assumed
47、to be equal to its W or D-Size Number. If the weight per square foot of welded wire fabric is given on the plans, that weight will be used. The weight of reinforcement used in items such as rail- ings and precast members, where payment for the rein- forcement is included in the contract price for th
48、e item, will not be included. Threaded bars or dowels placed after the installation of precast members in the work and used to attach such members to cast-in-place concrete will be included. No allowance will be made for clips, wire, separators, wire chairs, and other material used in fastening the
49、rein- forcement in place. If bars are substituted upon the Con- tractor?s request and as a result more reinforcing steel is used than specified, only the amount specified will be included. The additional reinforcing steel required for splices that are not shown on the plans but are authorized as pro- vided herein, will not be included. No allowance will be made for the weight of epoxy coating in computing the weight of epoxy-coated rein- forcing steel. 9.11 PAYMENT Payment for the quantity of reinforcement determined under measurement for each class of reinforcing steel shown in the bid sche
