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  1. Bridge wire cable. Bridge wire cables used for suspenders shall be either bridge strand or bridge rope fabricated from galvanized bridge wire.
    1. WIRE. Wire shall be produced from rods rolled from high carbon steel, the composition of which shall be controlled to provide internal soundness, uniformity of chemical composition and physical properties, freedom from injurious surface imperfections, and shall meet the following requirements.
      1. The minimum ultimate tensile strength of zinc-coated wire shall be as follows:

        Class A coating .............. two hundred twenty thousand psi

        Class B coating .............. two hundred ten thousand psi

        Class C coating .............. two hundred thousand psi
      2. Yield strength shall be one hundred fifty thousand psi minimum for zinc-coated wire with class A or class B coating, one hundred forty thousand psi minimum for zinc-coated wire with class C coating, based on the cross-sectional area of the coated wire when loaded to 0.7% elongation in a ten inch gage length. In determining the yield strength, an initial stress equivalent to forty-two thousand psi, based on cross-sectional area of the coated wire, shall be applied to the wire sample. At this loading, the entensometer shall be attached and an initial dial reading set at the equivalent of 0.15% elongation.
      3. Elongation shall be four percent minimum in a ten inch gage length, determined as the permanent increase in length after failure of a marked section of the wire originally ten inch in length except that a value of two percent will be permitted for wires 0.110 in. or less in diameter having a class A zinc coating.
      4. The zinc-coated wire must withstand wrapping at a rate not exceeding fifteen turns per minute twice around a mandrel equal to three times the wire diameter without fracture of the steel.
      5. The wire used in bridge strand or bridge rope shall be zinc-coated (galvanized) in accordance with the requirements of table 10-5. Weight of coating shall be determined in accordance with the provisions of reference standard RS 10-24.

        TABLE 10-5
        MINIMUM WEIGHTS OF COATING-BRIDGE WIRE, ZINC-COATED, FOR BRIDGE STRAND AND BRIDGE ROPE CONSTRUCTIONS
        Diameter of coated Wire (in.) Minimum Weight of Coating (Ounces per Sq. Ft. of Uncoated Wire Surface)
        Class A Class B Class C
        0.041 to 0.061 incl. 0.40 0.80 1.20
        Over 0.061 to 0.079 incl. 0.50 1.00 1.50
        Over 0.079 to 0.092 incl. 0.60 1.20 1.80
        Over 0.092 to 0.103 incl. 0.70 1.40 2.10
        Over 0.103 to 0.119 incl. 0.80 1.60 2.40
        Over 0.119 to 0.142 incl. 0.85 1.70 2.55
        Over 0.142 to 0.187 incl. 0.90 1.80 2.70
        Over 0.187 1.00 2.00 3.00
    2. BRIDGE STRAND. Bridge strands shall be made from wires complying with subparagraphs a through e of paragraph one of this subdivision, and shall meet the following requirements:
      1. The wires shall be made in such lengths that the strands can be manufactured with no splices in the outside wires. Splicing of inner wires during the stranding operation is permissible. When joints are necessary in any wires, they shall be electrically butt welded and shall be recoated in a workmanlike manner. Joints in the wires of strand shall be made and dispersed in a manner that will maintain the minimum specified breaking strength of the strand.
      2. The minimum breaking strength shall be based on tests to destruction and shall be certified by the manufacturer.
      3. Bridge strand shall be prestretched to produce a stable modulus of elasticity of at least the following values for strand wires having class A coating: one-half inch to two and nine-sixteenths

        inches dia. ................................. twenty-four million psi two and five-eighths inches and larger ........ twenty-three million psi

        For bridge strands that have classes B and C zinc-coating on the outside wires, the modulus of elasticity shall not be more than one million psi less than the corresponding values for bridge strand with a class A coating. The pre-stretching load shall not exceed fifty-five percent of the breaking strength of the strand.
    3. BRIDGE ROPE. Bridge rope shall be made from wires complying with subparagraphs a through e of paragraph one of this subdivision, and shall meet the following requirements:
      1. Joints are permissible in inner and outer wires and shall be electrically butt welded and shall be recoated in a workmanlike manner. Joints in the wires of strand shall be made and dispersed in a manner that will maintain the minimum specified breaking strength of the rope.
      2. The minimum breaking strength shall be based on tests to destruction and shall be certified by the manufacturer.
      3. Bridge rope shall be prestretched to produce a stable modulus of elasticity of at least twenty million psi for rope wires having a class A coating. For bridge rope that has class B and C zinc-coatings on the outside wires, the modulus of elasticity shall not be more than one million psi less than the corresponding value for bridge rope with a class A coating. The prestretching load shall not exceed fifty-five percent of the breaking strength of the rope.
  2. Other materials. Any structural material permitted for use under the provisions of other sections of this subchapter may be used for support of a suspended structure including, but not limited to, types of steel permitted for use under the provisions of reference standard RS 10-5; reinforcing steel and wire, prestressing wire and strand, and high strength alloy steel bars conforming to the requirements of reference standard RS 10-3; and steel conforming to the requirements of reference standards RS 10-66 and RS 10-69. Prestressing wire and strand may be used for suspenders without the application of prestressing force. All such suspenders shall be protected as described in section 27-642 of this article.

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