Guidelines for Inspection and Strength Evaluation of Suspension Bridge Parallel Wire Cables (2004)

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D-1 CONTENTS APPENDIX D SPLICING NEW WIRES...........................................................................................................D-1 D.1 SPLICING NEW WIRES INTO THE CABLE.......................................................................................D-2 D.1.1 Introduction........................................................................................................................................D-2 D.1.2 Typical specification for splicing wires ............................................................................................D-2 D.1.2.1 WIRE SPLICING COMPONENTS................................................................................................D-2 D.1.2.2 VERIFICATION TESTING OF WIRE SPLICING COMPONENTS ...........................................D-2 D.1.3 Wire splicing procedure ....................................................................................................................D-3 D.2 MEASURING THE WIRE TENSION.....................................................................................................D-4 D.2.1 Calibration..........................................................................................................................................D-4 D.2.2 Measuring procedure ........................................................................................................................D-4

D-2 D.1 SPLICING NEW WIRES INTO THE CABLE D.1.1 Introduction Whenever a sample wire is removed from the cable, or a broken wire is found there, it is necessary to replace the removed or corroded section of wire by splicing in a new wire. The usual method is to attach two lengths of new wire to the cut ends of the original wire with pressed-on, or swaged, ferrules, and then to connect the ends of the two new wires with a threaded ferrule that acts like a turnbuckle. The pressed-on ferrules can develop at least 90% of the strength of the wires. The threaded ferrule somewhat less, usually 75% to 85%, because of the section loss in the threads: rolled threads develop strength near the upper limit, cut threads near the lower limit. D.1.2 Typical specification for splicing wires D.1.2.1 WIRE SPLICING COMPONENTS • The material for the new wires shall conform to ASTM A586 specifications for tensile strength, elongation in a 10-inch-gage length and reduction of area. Single wires of sufficient length for the longest replacement shall be provided, with a left-hand thread at one end and a right-hand thread at the other. • Threaded ferrules, pressed-on ferrules and equipment for the installation shall be manufactured and certified subject to the engineer’s approval. D.1.2.2 VERIFICATION TESTING OF WIRE SPLICING COMPONENTS Verification testing shall be performed to confirm that the required specifications for these components have been met, as follows: • Threaded ferrules shall be tested by fully connecting the ferrule to the threaded ends of two new wires. They shall develop at least 75% of the ultimate strength of the new wires. • Pressed-on ferrules shall be tested by fully connecting the ferrule to the smooth ends of two new wires using field equipment. Pressed-on ferrules shall develop at least 90% of the ultimate strength of the new wires. • Wires used in these tests shall have been previously tested and certified by the manufacturer and accepted. Assemblies of ferrules and wires for testing shall be made by the contractor’s field personnel, in order to qualify them to do the work. Testing shall be performed by an approved testing laboratory. The wire used in verification testing shall be provided by the contractor from the lot of wire to be used in the actual work. The sample for testing each component shall be 1% of each lot or 10 specimens, whichever is greater. A lot is defined as the number of components contained in a single shipment. Each component shall be packed separately, and each package shall be clearly labeled, noting the specific component and the number of pieces. Packages that lack the required labeling may be returned to the place of manufacture uninspected, untested, and unaccepted. No extra compensation shall be granted, nor extension of time allowed for any delays attributable to the return of unlabeled or poorly labeled packages. All of the specimens that constitute the first sample shall be tested before a second sample is taken. If more than one specimen from the first sample fails the required testing, then the entire lot shall be rejected. If one specimen of a sample fails the required testing, then an additional random sample, equal in number to the first sample, shall be taken. If one specimen of the second sample fails the required testing, then the entire lot shall be rejected. The contractor is notified that the testing procedure will render the tested specimen unfit for further use, and that all tested specimens shall be discarded after testing has been completed. The contractor is advised to order a sufficient number of components to allow for testing and discards and still have enough left to do the work.

D-3 D.1.3 Wire splicing procedure • Remove the wire sample or portion of broken wire as directed by the engineer. • • Clean the ends of wires #1 and #4 and the unthreaded ends of wires #2 and #3 to bright metal for a length of 2 inches. The (spliced) ends of wires shall be kept clean and free of dirt, oil and any other foreign material throughout the procedure. • Connect the ends of the existing wires #1 and #4 to splice wires #2 and #3 as follows (see Figure D.1.3-1): • Splice existing wire end #1 to the unthreaded end of splice wire #2 using pressed-on ferrule A. This operation is shown in Figure D.1.3-2. • Splice the threaded end of splice wire # 2 to threaded end of splice wire #3 using threaded ferrule B. • Tension wires #3 and #4 to a load equal to the dead load tension in the cable using come-alongs equipped with suitable wire grips. Trim the end of wire #3. A gap of approximately 1/4 to 3/8 of an inch shall be provided between wires # 3 and # 4. • Disconnect the threaded ferrule between new wires #2 and #4. • Splice the unthreaded ends of wires #3 and #4 using pressed-on ferrule C. • Attach come-alongs and suitable wire grips to wires #2 and #3. Install threaded ferrule B. Tension the wire assembly to a load equal to the dead load tension in the cable. Use threaded ferrule B as a take-up system. A suitable dynamometer or load cell shall be used for wire tension control. Existing wire after sampling or removal of corroded section Pressed-on ferrules New wires Threaded ferrule Existing wire after sampling or removal of corroded section 1 2 3 4Wire number A CB Figure D.1.3-1. Wire splicing. Cut one new wire into two pieces, numbered #2 and #3 on Figure D.1.3-1. Piece #2 shall be of a length that places the threaded ferrule at the desired location. One end of each of these pieces will be threaded, the other plain

D-4 Figure D.1.3-2. Applying ferrules with a hydraulic ram. D.2 MEASURING THE WIRE TENSION After the new wire is spliced into the cable, the tension shall be measured and adjusted to within 10% of the dead load tension in the wires. The tension is measured with the device shown in Figure D.2-1, which shall be fabricated and calibrated in advance of the work. Calibration is necessary rather than calculating the wire tension indicated by an induced offset, because the flexural stiffness of the wire as well as its cast will affect the force vs. deflection curve. D.2.1 Calibration Calibration shall be performed by an approved testing laboratory. A piece of bridge wire 20 feet long shall be placed in a testing machine and stressed in increments of 100 pounds. The force required to cause a deflection of the wire between the ends of the device shall be measured using the same spring balance that will be used in the field. The recommended offsets are given in Table D.2.1-1; these offsets should result in the required force of approximately 60 pounds. Table D.2.1-1 Recommended offsets for various wire tensions Wire Tension (pounds) Offset (inches) 1500 0.70 2000 0.55 2500 0.45 A calibration curve shall be prepared, with applied force as the abscissa and wire tension as the ordinate. The offset used shall be shown on the calibration curve. D.2.2 Measuring procedure The device is held against the wire, which is in contact with the grooves in the end plates. Only enough pressure is used to achieve contact with the wire; the tube is not bent. The center hook is pulled outward with a spring balance until the offset is exactly equal to the calibration offset and the applied force is measured. The wire tension is determined from the calibration curve.

D-5 6’ 0” Force to deflect wire measured by spring balance2” x 2” x 1/8” alum. tube 1/4” alum. plate Weld Cable wire Ruler attached to tube Hole to clear rod Figure D.2-1. Wire tension measuring device.