20.Supply And Erection Of Cablework
[This section requires effective proof reading and altered as deemed necessary. It also requires a critical review in the light of more current practice, codes and specifications.]
20.1General
Note, and comply with, the requirement of the Preliminary clauses.
Submit full details of the method of construction and all alternative connections with the tender.
This section applies to:
the supply, fabrication, handling, and placement of steel wire rope and strand, and,
the erection of the superstructure of the catenary bridge.
Comply with AS2759, Steel wire rope –Use, Operation and Maintenance unless otherwise specified.
20.2Standards
The specification Clauses take precedence over the following standards.
Conform to the following standards unless specified otherwise:
AS 1138Thimbles for wire rope
AS/NZS 1252High Strength Steel Bolts with Associated Nuts and Washers for Structural Engineering
AS 1394Round steel wire for ropes
AS 1418Crane hoist and winches (Set)
AS 1554Structural Steel Welding (Set)
AS 3569Steel wire ropes
AS 1735Lift, escalators and moving walks (Set)
AS 2076Wire-rope grips for non-lifting applications
AS 2319Rigging screws and turnbuckles
AS 2740Wedge-type sockets
AS 2759Steel wire rope –Use, operation and maintenance
AS 2841Galvanised steel wire strand
AS 3600Concrete structures
AS 4100Steel structures
BS 463-1 Specification for sockets for wire ropes
Comply with the additional requirements of this Specification.
Comply with the requirements of this Specification if they contradict clauses in the above Standards.
20.3Alternative Connections
Alternatives will be considered to:
the rope and strand connections and fittings,
the type and specification of wire rope,
the terminal fittings, anchorage hinges, and adjustment details of the strands,
"Alternatives" in the form of additional fittings or modifications to the specified fittings to facilitate a particular construction technique will also be considered.
Submit full details, specifications, computations, and fabrication drawings of alternative connections, modifications, and fittings for approval.
Alternatives will not be considered if the above details are not included with the tender or are not sufficiently clear and detailed.
Do not commence fabrication of any proposed alternatives before receiving that approval.
Provide alternatives that are stronger, stiffer, and more durable, than the specified connections (unless otherwise approved).
Provide alternatives that are fatigue and vibration resistant.
Aesthetics are an important consideration. Alternatives will be rejected if the Superintendent considers that they are not as attractive or appropriate as the details shown on the drawings.
Provide evidence that proposed connections will meet these requirements.
Load test alternative connections in the same manner as the specified connections unless the specification requires additional proof testing.
Bear all costs and expenses related to the load tests, retests, and providing evidence of compliance.
Make allowance for the time required to fabricate specimens of the proposed connections, test, record, analyse, and report results.
Make allowance for the time it takes for approval to be given.
Approval (or rejection of the alternative) will be given two weeks after the Superintendent receives the written request and all the essential details, data, computations, and test results that he needs in order to assess the proposal and consider the structural consequences.
Submit a tender price based on the details specified in the drawings.
If the cost of the alternatives are different to the conforming tender, submit an additional priced tender based on the proposed alternatives. No variations will be allowed to the prices of the alternatives if details change during construction.
20.4Materials
20.4.1Wire Ropes And Strand
Supply all wire rope and strand.
Use wire rope having at least the same strength and stiffness as the specified wire.
Use Class A, finally zinc coated, Grade 1570 wire, unless otherwise approved.
Provide a Certificate of Compliance identifiable with the wire in the rope or strand or a Test Certificate proving compliance.
Use rope having wire rope core.
Use wire rope coated with a non-staining lubricant for dropper cables.
Use wire rope or strand coated with "black-jack" lubricant unless noted otherwise on the drawing.
20.4.2Strand and Wire Rope Fittings
Galvanise all fittings unless otherwise approved.
Use fittings that will develop at least 95 per cent of the breaking strength of the strand or wire (unless other requirements are specified).
Use fittings that have at least the same fatigue resistance as the generic types shown on the drawings: a very high fatigue resistance is essential.
Provide Certificates of Compliance (or Test Certificates) identifiable with the wire rope sockets and all other proprietary wire rope fittings proving compliance with this specification and the appropriate standards.
Comply with AS2759 when preparing and socketing with metal.
Comply with the manufacturer's instructions when preparing and socketing with resin sockets.
Test the quality of the cast resin in accordance with the manufacturer's instructions.
Obtain approval from the Superintendent before socketing any cable: supply full details and manufacturer's instructions with the written request for approval.
Cast the socketing material in the presence of the Superintendent.
Remove and replace non-complying sockets and sockets made without the presence of the Superintendent. The Superintendent may exercise his discretion and accept such sockets if they are proof tested by approved methods to 80 percent of the minimum breaking load of the strand (or rope) without slippage or permanent deformation.
Modify the dimensions of the hinges and anchorage brackets to accommodate the actual fittings proposed to be used in the works. Design them to have the same strength as those specified on the drawings.
20.4.3Proof Load Tests Cable Connections
When requested by the Superintendent, proof test completed cable connections.
Obtain approval for the method of proof testing.
Apply the load at a steady rate on the fitting.
Apply the load concentric with the cable axis.
Apply and release the load 10 times and measure the movement for each cycle of load.
Measure the movement of the fitting along the cable to an accuracy of .01mm.
Remove, replace (or rectify), and retest the fitting if it moves (slips) more than .05mm at the proof load on the tenth cycle of loading or the residual movement for the last cycle after release of the load is more than .02mm.
Bear the full cost and time delays associated with the proof loading and rectification of unacceptable fittings.
20.5Prototype Tests
Obtain approval for the details of the prototype testing.
Use the same materials and details in the prototypes as proposed for the actual structure.
Take up the cable slack by applying 10 per cent of the minimum test load.
Measure deflections from this point.
Apply the minimum test load ten times to each prototype.
Apply the test load smoothly.
Reduce the load to 10 per cent of the minimum test load at the end of each load cycle.
Continue the tenth application of load to failure of the prototype, or to the capacity of the test machine.
Measure the slip of the cable bracket along the cable, and to an accuracy of 0.01mm.
Measure the true and relative deflection of both ends of the prototype cables, and to an accuracy of 0.1mm.
Record the following for each test:
load deflection curve for each application of the minimum test load,
failure load,
a diagram describing the failed shape of the fittings,
permanent set (elongation) of the lateral cable during each application of the minimum test load,
the recoverable and non-recoverable slip of the cable bracket along the cable during each application of the minimum test load.
20.6Method Of Erection
20.6.1General
Submit a fully completed Schedule of Information with the tender.
Supply the Superintendent with sufficiently clear and adequate details of the principle of the erection method for him to judge its suitability.
Erection methods will be deemed to be unsuitable if the supplied details indicate:
the method is unlikely to produce a structure meeting the Functional Requirements,
a lack of understanding of the manner in which the structure behaves and consequent risk of incorrect or unsafe construction practices,
a lack of effective safeguards to prevent fall of men, debris, or materials,
a significant risk of over-stressing of any fitting, equipment, or cable during the construction process,
insufficient scope within the method to allow for:
adjustment of the structure's shape due to fabrication and construction inaccuracies,
reasonable construction tolerances,
the difficulties of this site with regard to limited possible survey accuracy,
the roughness of the terrain and consequent variability of surface profile,
the flexibility of the structure (the structure will noticeably deflect during construction operations due to the operations themselves, non-uniform forces in the cables, inaccurate length of cables, changes in temperature, etc.).
the equipment or techniques are unlikely to be sufficiently accurate or adequate to measure the forces in the cables or to achieve the required tolerances.
Wait for approval for the method of erection before fabricating any strand or rope.
Wait for approval for the design of the temporary works before beginning any erection work. Approval will be given within two weeks of the Superintendent's receipt of complete information and computations that prove compliance with the Functional Requirements.
Submit the following, with the written request for approval of the temporary works:
name, curriculum vitae, and photocopy of the degree of the structural engineer taking responsibility for the design calculations of the temporary works,
certificate of compliance signed by the structural engineer certifying that all the specified Functional Requirements of the method of construction have been considered and met, and summarising the assumed:
dead, live, and construction loads,
construction wind velocities, drag coefficients, and pressures,
extreme construction temperatures,
detailed construction sequence and its implications for the design,
effect of the construction operation and its loads on the permanent structure,
bound set of complete, neat, indexed, clear computations for the temporary works and the stresses in the permanent works caused by the erection process,
set of final, detailed, construction drawings for the temporary works.
Assume full responsibility for the adequacy and success of the method of construction and for the design of temporary works and equipment. The approval given by the Superintendent signifies that the principles of the methods are reasonably sound and are likely to be feasible if executed properly and in a fashion consistent with the underlying assumptions.
Assume full responsibility for the accuracy and correctness of computations. The Superintendent's check of the Contractor's computations and drawings will be essentially a superficial examination to ensure general correctness of approach, techniques and principles and will not be an exhaustive and complete investigation: approval does not signify that all the computations and drawings are without error although all detected errors will be highlighted and may form the basis for withholding of approval.
20.6.2Measurement of Forces In Cables
Use equipment capable of measuring the forces in the cables to an accuracy of 2 percent of the force in the lateral.
Submit details of that equipment for approval and do not fabricate or order it until approved.
Calibrate the equipment:
at a NATA registered laboratory,
using an approved technique and equipment,
and, in the presence of the Superintendent.
Provide a calibration certificate giving appropriate calibration curves.
Do not use uncalibrated equipment.
Recalibrate if components of the equipment are changed due to malfunction or if directed by the Superintendent as a result of apparently erratic results.
20.7Tolerances
Comply with the following tolerances:Force in cables when the structure is complete / + or - 1 kN
Variation in position of cable supports and cable anchorages / + or - 20 mm
Variation in lateral, horizontal or vertical position of any point on cable / + or - 30 mm
Variation from specified slope of cable / + or - 0.01 m/m
Variation of the cable from a smooth curve / + or - 5mm in 3m
20.8Correction For Temperature
Comply with the specified tolerances when the average temperature of all strand and rope is 27°C.
All dimensions and cable forces specified and given on the drawings are valid when the temperature of the structure is 27°C. The geometry of the structure and the forces in the cables change when the temperature changes.
Measure geometry and forces in the laterals when all parts of the structure are at 27°C, or compute and make allowance for deformations and force variations caused by the actual temperature difference.
<DoI Bridgeworks Master – Dec 2012>
SUPPLY AND ERECTION OF CABLEWORK