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Design Resources

Design Requirements

  • Sheet Nomenclature

    "W" and "D" Designations

    Individual wire (plain and deformed) size designations are based on the cross-sectional area of a given wire. Gage numbers were used exclusively for many years but were eliminated in the 1970’s to reduce the confusion caused from the misunderstanding of how to read and understand the specified gage size. The prefixes “W” and “D” are used in combination with a number. The letter “W” designates a plain wire and the letter “D” denotes a deformed wire. The number following the letter gives the cross-sectional area in hundredths of a square inch. For instance, wire designation W4 would indicate a plain wire with a cross-sectional area of 0.04 in2; a D10 wire would indicate a deformed wire with a cross-sectional area of 0.10 in2. The size of wires in WWR is designated in the same manner.

    This system provides many advantages. Since the engineer knows the cross-sectional area of a wire and the spacing, the total cross-sectional area per foot of width can easily be determined. For instance, a D6 wire on 4” centers would provide 3 wires per foot with a total cross-sectional area of 0.18 in2/ft of width.

    When describing metric wire the prefix “M” is added. “MW” describes metric plain wire and “MD” metric deformed wire. The wire spacing in metric WWR is given in millimeters (mm) and the cross-sectional area of the wire is in square millimeters (mm2).

  • Sizing and Spacing

    Sizing and Spacing

    Wire Sizing and Spacing

    A list of every wire size available on the market today is found in this Table(Wire Size and Weight Table). Each manufacture has their on limitation. The only facility that can produce and weld a D32 to a D45 wire is Ivy's Houston facility. Most of the Ivy facilities have the ability to produce and weld up to a D31. Two other maunfacturers that can weld up to a D31 are Connecticut Steel and Oklahoma Steel.

    Spacing limitations are directly related to the welder's limitations. Prior to 2000 most welders were limited to even line wire (longitudinal wire) spacing (2",4"6",8",10".....). The Welding equipment being installed today is more technologically advanced and has the ability to do odd size line wire spacing (3.5",6.875"...) Cross wire spacing can be almost any dimension.

    Therefore from a fabrication point of view there are no particular ranges in size or minimum and maximum spacing. From a design point of view the ACI code has established some design parameters.

    Reinforcing shall not be spaced father apart than 3 times the wall or slab thickness. ACI 318 7.6.5

    Max Spacing by Code:

    Plain Fabric 12" ACI 318
    Deformed Fabric 16" ACI 318
    Slab on Grade 18"

    Variable Size and Spacing:

  • Understanding Stress-Strain Relationships
  • Wire Size Chart
  • Splicing

    • Tying and Splicing Requirements

      Smooth Welded Wire Reinforcement

      Because the surface of plain wire is smooth the building codes do not assign any bond strength value to lengths of plain wire. Therefore, lap splices of plain WWR depend solely on the welded intersections for bond and development. The plain WWR lap splice is made by overlapping one complete cross wire space plus 2 inches. The splice is then wire tied sufficiently to prevent the two adjoining sheets from displacing during concrete placement. Tying requirements vary widely with the wire size and spacing of the WWR, but it is common practice to tie at every 3 rd welded intersection, or about every 3 feet, whichever is less.

      The ACI 318 lap splice length for plain WWR is one space plus 2 inches, minimum of 6 inches or 1.5 times the development length, whichever is greater. Large wires at close spacings necessitate longer development lengths and therefore the lap splice lengths are also longer (see ACI 318 Sections 12.8 and 12.19 for development length and lap splice design information).

      The very nature of the splice creates inefficiencies within the splice zone. Larger wire spacings can create longer splice lengths, but there is a solution. Remember, the requirement of “one spacing of cross wires plus 2 inches” means two welded intersections from each sheet are required to be within the splice zone. The splice zone can be shortened by moving these two welded intersections closer together. To accomplish this, the spacing is reduced at the edges of the sheet. See the example shown in the figure.

      The area of steel within the splice zone can be more than twice that of the rest of the WWR sheet. Again, there is a solution. Smaller wires replace the two edge wires at each side of the sheet. These wires must be at least 40% of the area of the wire welded in the opposite direction. In the example, W4.4 wires are used to replace the W11.0 wires at the edges of the sheets. These smaller edge wires combined with the reduced spacing resulted in a 58% reduction of material within the splice zone in this example.

      Splicing - Smooth WWR

      Deformed Welded Wire Reinforcement

      Deformed WWR sheets can be spliced by overlapping welded intersections (called a “welded deformed wire reinforcement lap splice” in ACI 318-05), or by simply lap splicing the straight sections of overhanging wires at the perimeter of the sheets (called a “wire lap splice” in ACI 318-05). ACI 318 Chapter 12 provides for both types of lap splices for use in structural reinforced concrete applications.

      The “welded deformed wire reinforcement splice” takes advantage of the additional anchorage provided by the welded intersections in conjunction with the bond provided by the deformations along the surface of the wire. Unlike plain WWR splices, deformed WWR splices are required to have only one welded intersection from each sheet within the splice zone. The welded transverse wires must overlap one another by at least 2 inches and have sufficient wire length beyond the welded intersection to satisfy the minimum calculated splice length. Efficiencies can be gained by reducing the size of the transverse wires within the splice zone as long as the minimum cross sectional area of steel is provided in the transverse direction. This can be a very economical splice but can also create build-up at the splice zone, particularly where four sheets meet at one place. It is recommended that adjacent rows of sheets be offset slightly to avoid unnecessary build-up at the splice zone.

      The “deformed wire splice” does not require the overlapping of welded intersections, nor does it require that a welded intersection be in the splice zone at all. The splice is designed identically to a rebar lap splice (for #6 bars and smaller). Deformed wire splices are longer than deformed WWR splices but the build-up can be reduced or totally eliminated when the WWR sheets are placed in the proper sequence.

      Splicing - Deformed WWR
    • Calculate Splice Lengths for Smooth Wire
    • Calculate Splice Lengths for Deformed Wire
    • Use Graphs to Calculate Splice Lengths

Sample Specifications

  • Transportation Facilities


    Description : Portland Cement Concrete Pavement
    Effective Date: 01/01/2002

    Care shall be taken before and during paving operations to insure that the reinforcement (including dowels as well as tie bars) will stay within the plan tolerances after the finishing operations. Reinforced concrete pavement shall be placed in two layers except for continuously reinforced concrete, unless otherwise provided. The entire width of the bottom layer shall be struck off to such length that the sheet of fabric or bar mat shall be laid full length on the concrete in its final position without further manipulation. The reinforcement shall then be placed directly upon the concrete after which the top layer of the concrete shall be placed, struck off, and screeded as specified for plain concrete pavement in the preceding Subarticle. Any portions of the bottom layer which have been placed more than 15 minutes without being covered with the top layer shall be removed and replaced with freshly mixed concrete. With written approval of the Engineer, the Contractor may, by use of a satisfactory mechanical mesh placer, embed the wire mesh reinforcement in the concrete placed full depth in one layer in lieu of the two layer method. Approval of this method will be on a trial basis and subject to continued satisfactory operation of the mesh placing equipment. Reinforcing steel shall be free from dirt, oil, paint, grease, mill scale, and loose or thick rust which would impair bond of the steel with the concrete. Rust that produces only discoloration without reducing the cross section of the steel will not be considered objectionable. Bars shall be handled with such care that loose bars shall be free from kinks or bends sufficient to prevent proper assembly or installation. When bar mat assemblies or continuous reinforcement are used, the reinforcing shall be assembled, placed, secured (firmly fastened together at all intersections), and lapped as detailed on the plans.

    When steel fabric is used, it shall be placed in sheets or strips at the depth shown on the plans. Equal clearance shall be provided on each side of the slab, and successive sheets shall be lapped as called for on the plans. Reinforcement shall be continuous without interruption at emergency construction joints. All laps between sheets shall be held firmly together by wires or clips spaced not more than 4 feet {1.2 m} apart. Continuous reinforcement shall be installed in accordance with details shown on the plans. Preset chairs shall be similar to one of the alternates provided by the plans, or other approved devices. The height of preset chairs or supports shall be that shown on the plans within a tolerance of 1/8 of an inch {3 mm}; the arrangement and spacing shall be such that the reinforcement will be supported and held in the correct position within the allowable tolerances during the placing and consolidating of the concrete; sufficient bearing at the base of the device shall be provided to prevent overturning or penetration into the subbase; the design of the devices shall be as not to interfere with placing and consolidating the concrete.

    South Carolina
    Description : Portland Cement Concrete Pavement
    Effective Date : 01/01/2000

    501.09 Tie Bars, Dowel Bars, and Reinforcements .
    Wire and wire mesh shall conform to the requirements specified in Section 703.

    Slope Paving

    Description : Slope Paving
    Effective Date : 01/01/2002

    614.01 Description.

    This Section shall cover the work of paving with concrete any fill or cut slopes as shown on the plans or designated. The slope paving shall be laid to line, grade, and dimensions shown on the plans or directed.

    Slope paving shall include, but not be limited to, paving of slopes at bridge ends, under grade separation structures, concrete slope drains, paving of side ditches, median ditches, special ditches, and other designated areas for control of erosion. Slope paving shall include wire mesh or other type of reinforcement when and as shown on the plans.

    Description : 8-16 Concrete Slope Protection
    Effective Date : 1/01/2002

    8-16 Concrete Slope Protection

    8-16.3(3) Poured in Place Cement Concrete

    The wire mesh shall lap a minimum of one mesh spacing, and laps shall be securely fastened at the ends. During the placement of the concrete, the reinforcement shall be held so as to provide a minimum of 11/4 inch of cover. Where Class 3000 cement concrete is to be placed upon the slope, the method of depositing and compacting shall result in a compact, dense, and impervious concrete which will show a uniform plane surface.

    The newly constructed concrete shall be finished by means of a wood float and shall be striated with a rustication joint as shown in the Plans.

    Curing shall be performed in accordance with Section 5-05.3(13).

    8-16.3(4) Pneumatically Placed Concrete

    Reinforcement. The wire mesh shall lap a minimum of one mesh spacing, and laps shall be securely fastened at the ends. During the placement of the concrete, the reinforcement shall be held so as to provide a minimum of 13/4 inch of cover at the recess.

    Reinforcing Steel

    Description : Reinforcing Steel
    Effective Date : 08/01/2001

    1003 Reinforcing Steel
    Certificates of Compliance are required for reinforcing steel. The Certificate of Compliance for reinforcing steel should be received before payment is made. If the project requires epoxy coated bars then the epoxy resin must be on the Department's Approved Product List. The Inspector must ensure that any damaged to the epoxy coating is repaired in accordance with the Standard Specifications. Refer to the Materials Group Policy & Procedures Directives Manual for information on the sampling, testing, certification, and marking of reinforcing bars. Additional information on reinforcing bars and their dimensions can be found in Chapter 5, Section 605-2. The same general procedures are followed for wire mesh and smooth bars used as reinforcement except that there are no markings on the metal. The "W" size designation of wire mesh refers to the area of the individual wire in hundredths of a square inch. W5 wire has an area of 0.050 square inches (32.3 square millimeters) as shown in the following table (Exhibit 10-2). The Standard Specification allows substitution of Grade 60 reinforcing bars for Grade 40 in certain cases. When the substitution is permitted, the authorization is to be in writing.

    Description : Steel Reinforcement
    Effective Date : 01/01/2002

    DESCRIPTION. Steel for reinforcement of concrete shall be of the size and type specified in the contract documents and shall meet the requirements for the type and use specified. Chairs, bolsters, and other support devices, either plastic or steel, shall meet the requirements of Materials I.M. 451.01.

    Wire mesh used as conventional reinforcement shall be of the size and spacing shown in the contract documents and shall meet requirements of ASTM A 185.

    Description : Reinforcement for Concrete Structures
    Effective Date : 01/01/2001

    421.01 DESCRIPTION. This work shall consist of furnishing and placing reinforcement, including deformed steel bars, wire mesh, and plain round steel spiral bars, as specified in the Contract Documents or as directed by the Engineer. Reinforcement shall be uncoated or epoxy coated as specified in the Contract Documents.

    421.02 MATERIALS.
    Wire Mesh 908.05 and 908.06

    Welded steel wire fabric shall conform to M 55. Fabric used in pavement construction shall be furnished in flat sheets.

    Welded deformed steel wire fabric shall conform to M 221.

    Description : Reinforcing Steel for Structures
    Effective Date : 8/12/1999

    511.01. DESCRIPTION.
    This work consists of furnishing and placing reinforcing steel in accordance with the contract documents. Reinforcing steel consists of deformed bars, epoxy coated deformed bars, and cold drawn wire mesh as specified.

    Puerto Rico
    Description : Reinforcing Steel
    Effective Date : 01/01/1989

    602-3.04 Placing and Fastening
    Wire mesh reinforcement which is received in rolls shall be straightened out into flat sheets prior to placing.

    All reinforcement shall be furnished in the full length indicated on the plans. Splicing, except where shown on the plans, will not be permitted without the approval of the Engineer and shall comply with the following:

    Wire mesh or bar mat reinforcement shall be spliced by overlapping sufficiently to maintain uniform strength and shall be securely fastened at the edge and end laps. The edge lap shall be not less than one full mesh in width.

    South Carolina
    Description : Reinforcing Steel
    Effective Date : 01/01/2000

    703.01 Description. Work under this section shall consist of furnishing and placing concrete reinforcing steel consisting of bars, wire, wire mesh, bar supports and ties.

    703.02 Reinforcing Bars. Reinforcing bars and dowels shall conform to AASHTO M 31 (ASTM 615), Deformed and Plain Billeted-Steel Bars for Concrete Reinforcement, and shall be Grade 60 unless otherwise specified. Acceptance or rejection shall be based on 36 inch long samples taken in the field.

    703.03 Wire and Wire Fabric. Wire for concrete reinforcement, either as such or in fabricated form, shall conform to AASHTO M 32 (ASTM A 82), Steel Wire, Plain, for Concrete Reinforcement or AASHTO M 225 (ASTM A 496), Steel Wire, Deformed for Concrete Reinforcement. Welded steel wire fabric for concrete reinforcement shall meet the requirements of AASHTO M 55 (ASTM A 185), Steel Welded Wire Fabric, Plain, for Concrete Reinforcement.

    Description : Reinforcing Steel
    Effective Date : 01/01/2002


    This work shall consist of furnishing; coating, if required; and placing reinforcing steel or wire mesh used in concrete operations, except prestressed strands and wires, in accordance with these specifications and in reasonably close conformity to the lines and details shown on the plans.

    (c) Welded wire fabric shall conform to the requirements of Section 223.

    (c) Welded wire fabric shall conform to the requirements of Section 223 .

    (e) Splicing and Lapping : ………………………….Laps for sheets of welded wire fabric or bar mat reinforcement shall be at least one mesh in width.

    Description : Reinforcing Steel
    Effective Date : 1/01/2002

    9-07.7 Wire Mesh
    Wire mesh for concrete reinforcement shall conform to the requirements of AASHTO

    M 55, Welded Steel Wire Fabric for Concrete Reinforcement or AASHTO M 221, Welded Deformed Steel Wire Fabric for Concrete Reinforcement. All wire mesh shall be of an approved kind and quality of manufacture.

    Drainage Structures

    Description : Structural Steel, Fasteners, and Miscellaneous Metals
    Effective Date : 01/01/2002

    WELDED WIRE REINFORCEMENT. - Welded plain wire reinforcement mesh shall meet the requirements of AASHTO M 55. Welded deformed wire reinforcement mesh shall meet the requirements of AASHTO M 221.

    Description : 901 Cement Concrete Masonry
    Effective Date : 01/01/1995

    901.61 Reinforcement.
    When wire mesh is used as reinforcement, it shall be furnished and placed in accordance with the plans. If the wire mesh is shipped in rolls, it shall be straightened into flat sheets before being used.

    Description : 930 Prestressed Concrete Beams
    Effective Date : 01/01/1995

    Reinforcement for cement concrete masonry structures shall be measured by the kilogram. The mass of bars shall be the product of the length as shown on the approved plans and schedules and the standard mass per meter of length as adopted by the Concrete Reinforcing Steel Institute. Wire, metal clips, metal chairs or other fastening and supporting devices used for keeping the reinforcement continuous and in correct position will not be considered reinforcement and the Contractor will receive no additional compensation for their use. The mass of wire mesh (incorporated in the structure) shall be the computed mass in accordance with the plans based on the standard mass accepted by the trade for the unit area of the particular mesh.

    901.81 Basis of Payment.
    Steel reinforcement including wire mesh will be paid for at the contract unit price per kilogram under the item for Steel Reinforcement for Structures, complete in place. No payment will be made for any fastening devices or supports that may be used for keeping the reinforcement in correct position. Galvanized steel curb bars and steel dowels will be paid for at the contract unit price per kilogram under the item for Steel Reinforcement for Structures.

    Description : 3236 Reinforced Concrete Pipe
    Effective Date : 01/01/2000

    A4 Metal Reinforcement ................................................... 2472

    B. Pipe Design
    Placement of reinforcement shall be in accordance with applicable AASHTO Specification, except as otherwise required by the Plans or approved by the Engineer. Elliptical reinforcement will not be permitted in circular pipe. Wire mesh shall be lapped a minimum of one full mesh or twenty wire diameters, whichever is greater. Laps may be welded for pipe, however, only welders approved by the Materials Engineer may perform this task.

    Description : Bridges
    Effective Date : 01/01/2002

    00596.15 Steel - Provide structural steel according to Section 00560 and the following:

    (2) Reinforcing Mesh - Furnish welded wire reinforcement according to 02510.40 supplemented and modified as follows:

    a. Galvanized Reinforcement - Provide a minimum 600 g/m2 (2.0 ounce per square foot) galvanized coating for welded wire embedded in either concrete or soil according to ASTM A 641/A 641M.

    b. Epoxy Coated Reinforcement - When specified, provide a Class A coating for welded wire reinforcement embedded in concrete and a Class B coating for welded wire fabric embedded in soil according to ASTM A 884/A 884M.

    South Carolina
    Description : Section 719 Catch Basins Drop Inlets Manholes Junction Boxes and Spring Boxes
    Effective Date : 01/01/2000

    719.10 Precast Reinforced Concrete Drainage Structures . Subject to the approval of the Engineer, the Contractor may substitute precast reinforced concrete drainage structures for constructed-in-place structures shown on the plans. If precast structures are specified on the project, or if the Contractor is allowed to substitute precast alternates, they shall conform to the details shown on the plans and the applicable provisions of this specification. Precast concrete drainage structures shall be designed for HS-25 loading. Concrete shall be Class 4000 portland cement concrete conforming to the requirements of Section 701 . Reinforcing steel shall conform to AASHTO M 31, Grade 60. Wire Mesh shall conform to AASHTO M 55 and M 221.

  • WRI Sample Specification
  • Construction Standard Spec

WWR vs Rebar

Codes and Standards

  • Codes and Standards
  • Bends and Hooks

    ACI 318: Section 7.2.3

    Describes WWR Bending Criteria

    This section and its commentary are shown below.

    7.2.3 -- Inside diameter of bend in welded wire fabric (plain or deformed) for stirrups and ties shall not be less than 4db for deformed wire larger than D6 and 2db for all other wires. Bends with inside diameter of less than 8db shall not be less than 4db from nearest welded intersection.

    R7.2.3 -- Welded wire fabric, of plain or deformed wire, can be used for stirrups and ties. The wire at welded intersections does not have the same uniform ductility and bend-ability as in areas which were not heated. These effects of the welding temperature are usually dissipated in a distance of approximately four wire diameters. Minimum bend diameters permitted are in most cases the same as those required in the ASTM bend test for wire material (ASTM A 82 and A 496).