High strength steel structure bolt connection pair large hexagonal head torsional shear type bridge building special fastener

Description :

  Steel structure bolts are high-strength fasteners specifically used for connecting steel structure nodes, mainly solving the problem of rigid or hinged connections between steel beams, steel columns, and supporting components. In large factories, high-rise buildings, bridges, and tower structures, it transmits shear force by generating frictional force between connecting plate layers through pre tension, ensuring the overall stability and safety of the structure. This type of bolt is usually divided into two categories: large hexagonal high-strength bolts and torsion shear high-strength bolts. It needs to be used in conjunction with nuts and washers to form a connection pair, and is suitable for key stress bearing parts that can withstand dynamic or static loads. It is the core connecting component of modern prefabricated steel structure buildings.

  This series of products is strictly manufactured in accordance with national standards GB/T 1231 or GB/T 3632, and is usually made of high-quality carbon structural steel or alloy structural steel, such as 35 # steel, 45 # steel, or 20MnTiB. After heat treatment, the strength grade can reach 8.8S, 10.9S, or even 12.9S. Surface treatment methods include black coating, galvanizing, Dacromet or Geometric coating to enhance corrosion resistance. The specification range covers various nominal diameters such as M12 to M36, and the length is customized according to the thickness of the connecting plate. The product needs to pass wedge load test, guarantee load test, torque coefficient or fastening axial force test to ensure stable mechanical performance. Each batch of products comes with a factory certificate and inspection report, which comply with the construction project quality acceptance specifications.

  When selecting, it is necessary to clarify the strength grade, connection form, and friction surface treatment method required by the design. The construction of large hexagonal bolts requires a torque wrench to control the pre tension in two steps: initial tightening and final tightening, which is suitable for scenarios with open space and easy operation; Twisted shear bolts are completed by using a plum blossom head to indicate the final tightening, which has high construction efficiency and is not affected by human torque errors, making them suitable for dense nodes or high-altitude operations. If the connecting surface is a high anti slip coefficient surface treated with sandblasting or shot blasting, high-strength bolts should be selected; Ordinary C-grade bolts are only suitable for secondary structures or temporary fixation. Attention should be paid to the accuracy of bolt hole positions to avoid forcibly tapping into the hole, which may cause loss of prestress or bending of the screw. It is strictly prohibited to mix bolt components from different batches or manufacturers.

  Before installation, it is necessary to check whether the connection contact surface is flat, free of floating rust and oil stains, and whether the anti slip coefficient of the friction surface meets the design requirements. During construction, twisting should be applied from the center of the node to the edge in the prescribed order to prevent warping of the board layer. In daily maintenance, it is necessary to regularly check whether the nodes are loose, corroded, or cracked, especially in environments with high vibration or corrosiveness. For exposed threaded parts, it is recommended to apply anti rust grease for protection. If it is found that the plum blossom head is not twisted or the torque is insufficient, it should be immediately tightened or replaced; It is strictly prohibited to reuse the bolts that have been finally tightened, in order to avoid connection failure due to material plastic deformation and ensure the safe operation of the steel structure throughout its entire life cycle.

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