Technical Specification for Concrete Circular Reinforced (Prestressed) Pole

2017-11-23 11:19:26 grant 10

Technical Specification and Standard for Concrete Circular Reinforced (Prestressed) Pole

 

 

 

Chapter 1 General Provisions

Article 1.1 In order to implement"Circular prestressed concrete pole" standard, strengthen enterprise quality management, ensure finished concrete electric poles quality, this standard is specially worked out for concrete pole plants complying.

Article 1.2 This procedure applies to prestressed concrete pole and reinforced concrete poles produced according to GB / T4623-2006.      

Article 1.3 The Technical specification of this technology is based on GB / T4623-2006 "circular concrete pole" and GB50204 "concrete structure construction and acceptance of norms" and other relevant standards and norms.

Article 1.4 If Any new technologies, new processes and new materials are applied, they shall be tested and identified before they can be used. If the construction of new technologies is inconsistent with these rules.

Article 1.5 The production workshop shall strictly implement the technical regulations and formulate relevant operational instructions in the light of the actual production.

Chapter 2 Technical Requirements for Raw Materials

 

 

Article 2.1 steel wire

Article 2.1.1 The specifications of the steel wire used in the concrete poles shall conform to the requirements of the design drawings. Into the factory steel should be quality assurance, and after passing the test before use. Variable cross-section reinforcement should be preferred. Steel plate ring and flange plate should be used with Q235B .

Section 2.1.2 Technical requirements and acceptance regulations of steel material.

Article 2.1.2.1 ordinary steel technical performance should be consistent with GB1499 "reinforced concrete with steel", GB13013 "reinforced concrete hot rolled round bar" and GB700 "carbon structural steel" and other standards.

Article 2.1.2.2 Reinforcement processing shall comply with the provisions of GB50204 "Code for Construction and Acceptance of Concrete Structures".

Article 2.1.2.3 The technical requirements for carbon steel wire and scoring steel wire shall comply with the provisions of GB / T5223, GB / T5223.3 "Prestressed concrete wire (rod)".

Article 2.1.2.4 cold-drawn low-carbon steel wire technical requirements should be consistent with JGJ19-1992 "cold-drawn steel wire prestressed concrete components design and construction procedures" requirement.

Article 2.1.2.5 of all steel (wire) should be GB50204 "concrete structure construction and acceptance of norms" provisions for acceptance.

Article 2.1.3 bars (wire) after passing the inspection, according to different steel mills, different batch number, different specifications, different strength were stacked, not mixed, and should avoid corrosion and pollution.

Article 2.2 cement

Article 2.2.1  Cement should be used Portland cement, ordinary Portland cement, its performance should be consistent with: GB175 "Portland cement, ordinary Portland cement." Cement strength grade are not less than 42.5.

Article 2.2.2 There should be quality assurance when cement enters the plant , different varieties, different grades of cement should be stacked in accordance with the order of the plant. Storage should be moisture-proof measures, and check once a week.

Article 2.2.3 Cement storage shall not exceed three months, expired or have doubts about the quality, shall be re-tested as required.

Article 2.2.4 When using bulk cement, different manufacturers, different varieties, different grades of cement shall not be mixed in the same tank, the cement should not have debris and agglomeration.

Article 2.2.5 When using bags of cement, different manufacturers, different grades, different varieties of cement shall not be mixed, the cement should not be caught debris and agglomeration.

Article 2.3 sand

Article 2.3.1 should be used in the texture of the hard sand, the fineness of the modulus should be 2.3-3.2, mud content of not more than 2%, the other requirements in line with GB / T14684 "building sand" requirement.

Article 2.4 Stone

Article 2.4.1 shall be treated with crushed stone after the sludge is not more than 1%, the maximum particle size of not more than 25mm, and less than the minimum spacing of steel 3/4, needle-like particles shall not exceed 10%, the other The requirements shall comply with the relevant provisions of GB / T14685 "gravel for construction".

Article 2.5 water

Mixing concrete should use tap water and clean natural water, and in line with JGJ63 "concrete mixing water" requirement.

Article 2.6 admixture

The use of admixture should be in accordance with GB8076 "concrete admixture" and GB8077 "concrete admixture homogeneity test method" of the relevant provisions of the test, the selection of qualified varieties and determine the content.

Chapter 3 Technical Requirement of Reinforcement processing and semi - finished products

Article 3.1 Reinforcement Processing

Article 3.1.1 bars shall not have necks, the surface shall not be cracked or damaged. Steel and steel wire surface should be clean, if grease, paint, floating skin, etc. should be eliminated before use clean.

Section 3.1.2  Prestressed steel wire should adopt variable cross-section steel wire.

Article 3.1.3  the steel bar or curved steel bars should be straightened straight, straightened after the steel (wire) should be straight, smooth face, no local twists and turns.

Section 3.1.4 The prestressed steel wire are processed with straightening, fixed length after cutting the relative length of the error is not greater than 1.5 / 10000.

Section 3.1.5 non-prestressed steel joints shall be welded butt welding, welding technology, performance should be consistent with GB50204 and JGJ18-2003 requirements, the joint strength of not less than the standard strength of the material.

Section 3.1.6 hot-rolled steel bar for cold-drawn reinforcement, should be welded after the pull. The total elongation of the cold drawn is not more than 10% of Grade I steel, not more than 5.5% of grade Ⅱ steel, not more than 5% of grade Ⅲ steel and not more than 4% of grade Ⅳ steel. The cold draw rate shall be determined by experiment, and when the average cold draw rate is less than 1%, the cold drawn is still carried out at 1%.

Article 3.2 semi-finished product skeleton

Article 3.2.1 steel semi-finished products should be produced according to the design drawings, longitudinal reinforcement of the number of bars, diameter, net distance should be consistent with GB / T4623-2006 standards.

Section 3.2.2 The diameter and pitch arrangement of the spiral tendons shall comply with the following provisions:

Section 3.2.2.1 Spiral bar diameter: tapered rod with a slightly smaller diameter<190mm, 2.5 mm in diameter with spiral ribs; tapered rod with slightly diameter 190mm-230mm, 3.0mm in diameter of spiral rib; And the diameter of the equal diameter rod is greater than 230 mm, and the diameter of the spiral rib is 4.0 mm.

Section 3.2.2.2 Spiral tendon spacing: tapered rod with a minor diameter ≤ 190mm, pitch ≤ 120mm in the middle section, pitch ≤70mm in the 1.5m range; the tapered rod with a diameter greater than 190mm and the middle Segment pitch ≤ 100mm, both ends of the 1.5 meters within the pitch ≤ 70mm.

Section 3.2.2.3 of the main reinforcement layer 15-25mm, steel plate joints should be the top of the protective layer.

Section 3.2.3 Prestressed Reinforcement Semi - finished Products

Section 3.2.3.1 The strength of the heading bar of the assembly bar shall not be less than 95% of the standard strength of the material (the strength can be reduced when it is not reached); the diameter of the upsetting head is generally 1.5-1.8 times the diameter of the bar; Not skewed and cracked.

Article 3.2.3.2 on the ring should be seeking the park is, the park is not greater than 10mm, and according to specifications stacked, not mixed.

Section 3.2.3.3 of the prestressed steel wire ring, should be perpendicular to the longitudinal reinforcement, the spacing should not be greater than 1000mm.

Section 3.2.3.4 Prestressed steel skeleton production, sub-die forming and in-mold molding of the two processes, no matter what kind of process, the prestressed main reinforcement should be even along the poles arranged in a circular section, the main tendons should not be less than 25mm The Spiral tendons should be around the ends of the skeleton around 2-3 turns, the configuration should be consistent with the provisions of Article 3.2.2.

Article 3.2.4 Ordinary reinforced semi-finished products

Section 3.2.4.1 Welded joints shall not exceed 25% of the total cross-sectional area of the main bars within a range of 500 mm or less than 35 times the diameter of the main bars.

Article 3.2.4.2 on the ring should be parked, loss of the park is not greater than 10mm, the use of welding on the erection with the main reinforcement welding and vertical with the main tendons, the spacing should not be greater than 500mm.

Paragraph 3.2.4.3 Spiral bars shall be around 2-3 turns at both ends of the frame and shall be so arranged in accordance with regulation 3.2.2.

Article 3.2.4.4 Other shall meet the following requirements:

to prevent welding undercut defects, should not use too much current, welding gap shall not exceed the diameter of steel or steel plate thickness of 10%.

 the main bar and steel plate or flange welding, weld height should be greater than 35% of the diameter of welded steel bars, and not less than 4mm, the width should be greater than 80% of the diameter of welded steel bars, and not less than 8mm, the main reinforcement should be with the steel The circle or flange remains vertical.

weld should be smooth and uniform without interruption of the phenomenon, the molten metal should be welded in the seam should be scales, no cracks and bubbles. 
In order to ensure that the steel cage skeleton in the concrete ring section on the design position, steel skeleton along the vertical every 1.0 or 1.5 meters, evenly placed in the ring 3-4 cement pad or plastic pad.

Article 3.2.5 of the steel skeleton of the size of the tolerance shall not exceed the provisions of Table 1.

 

 

Chapter IV Molding Process Technical Requirements

Article 4.1 the preparation of concrete

Section 4.1.1 centrifugal concrete strength grade prestressed pole should not be lower than the C50, stripping strength should not be less than 30MPa; non-prestressed rod should not be lower than the C40, stripping strength should not be less than 20MPa. The concrete mix design should be determined by experiment.

Article 4.1.2 ingredients

Article 4.1.2.1 in strict accordance with the provisions of the mix of ingredients, the raw material weighing error: cement, water, admixture is not greater than ± 2%, sand, stone is not greater than ± 3%. Weighing equipment regularly check, weighing device should be checked before weighing, meet the requirements before use.

Article 4.1.2.2 should be measured with climate change sand, stone moisture content and timely adjustment of water-cement ratio, winter shall not contain ice.

Article 4.1.3 Mixing

Article 4.1.3.1 concrete should be stirred evenly, the mixing time is defined as 2-4 minutes.

Article 4.1.3.2 stirring the first tank concrete, the amount of cement and sand should be increased by about 10%.

Article 4.1.3.3 concrete mixture should be used with the mix, the longest parking time: when the room temperature below 20 ℃, not more than 1h; when the room temperature above 20 ℃, not more than 45min; concrete slump should be controlled In the 30-70mm.

Section 4.1.3.4 concrete temperature should not be lower than 10 ℃, winter temperatures below 5 ℃, should be used hot water mixing, the water temperature shall not exceed 60 ℃.

Article 4.2 Clear concrete pole molds

Article 4.2.1 concrete pole steel mold must be cleaned, steel mold inner wall and joints should be evenly brushing release agent.

Article 4.2.2 The steel frame in the mold must ensure that the design position in the concrete, the steel skeleton shall not be twisted. The position of the main bar, the spiral bar, the erecting ring and the embedded part must be checked and checked.

Article 4.2.3 filling concrete, in the slightly 1.5m should be filled with concrete, 0.5m at the root should be appropriate less irrigation.

Article 4.2.4 After filling the concrete, the joint should be clean, uniform symmetrical tightening screws. To prevent leakage of pulp, can take the appropriate sealing measures.

Article 4.2.5 contains debris or early condensed concrete shall not be used.

Article 4.3 applies prestressingforce

Article 4.3.1 pre-stressed tensioning equipment should be regularly maintained and verified, the calibration period should not be more than six months, long-term unused, should be fully tested before use.

Article 4.3.2 The equipment and instruments used for the application of prestressing shall be operated by hand.

Article 4.3.3 When the tensioning process occurs during the breakage frequency is too high, the tensioner oil spill serious, oil pressure gauge pointer can not be returned to zero or replace the oil pressure gauge, should re-check the instrument and check the tensioning machine The

Section 4.3.4 Tensioning the head of the machine is aligned with the axis of the steel mold, and in order to reduce the prestress loss, the super-tensioning,

Reinforcement: 0 → 105% → 90% → 100%

Wire: 0 → 103%

Section 4.3.5 Prestressed tendons for prestressed poles and partially prestressed poles, tension control stresses: carbon steel 0.75Fpyk, cold drawn low carbon steel wire 0.70Fpyk.

Section 4.3.6 The minimum control stresses for the IV, Ⅴ grade steel and carbon steel wire of partially prestressed pole rods with low pretreatment strength shall not be less than 0.4Fpyk.

Article 4.3.7 tension with the stress control method, the actual elongation of prestressed tendons and the calculated elongation difference of 10% or more, should promptly check the reason, the prestress tension value error does not exceed ± 5%.

Article 4.3.8 Quality requirements after tension:

Section 4.3.8.1 The tension of the tension plate or pendant plate shall not exceed 2 mm.

Paragraph 4.3.8.2 should not have broken ribs after tensioning.

Article 4.4 Centrifugal molding

Section 4.4.1 Centrifugal speed is divided into slow, medium and fast three, the rapid steel mold running wheel outer ring speed of not less than 14m / s, the specific slow, medium and fast centrifugal time according to the speed of the centrifuge, Concrete distribution uniformity and dehydration dense situation, through the theoretical calculation and practical test to determine.

Article 4.4.2 Centrifugal speed and time, the implementation of Table 2, Table 3 requirements.

 

 

 

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