Specification for high-strength bolts of steel grid frame

Specification for high-strength bolts of steel grid frame

Type and specifications

The thread specifications of high-strength bolts for grid structures range from M12 to M64, as shown in the "High strength bolts for steel grid bolt ball joints GB/T16939-1997". Among them, bolts below M20 are mostly used in decorative grid structures. Due to the fixed interrelationships in the construction of nodes, the screw length of each specification of high-strength bolts in the grid is also fixed, as detailed in relevant materials. The high-strength bolts and sleeves for the grid frame are matched, so the bolt specifications are determined based on the calculation of the sleeve pressure during node design of the compression member.

Quality inspection and acceptance

The main basis for product inspection and acceptance of grid high-strength bolts is Code for Acceptance of Construction Quality of Steel structural engineering GB50205-2001 and JG12-1999 Standard for Inspection and Acceptance of Steel Grid.

In the Code for Acceptance of Construction Quality of Steel structural engineering GB50205-2001, the grid high-strength bolts are used as standard parts for site inspection and acceptance. See Article 4.4 for details. Moreover, Article 4.4.5 specifically specifies the requirements for "surface hardness testing".

The main inspection items for high-strength bolts in JG12-1999 Steel Grid Inspection and Acceptance Standards include hardness, cracks, and length.

Solid shape

The shape is as shown in the figure. The special feature is that there is a sliding groove on the screw, and there is a deep groove near the head, which is where the fastening screw (pin) on the matching "sleeve" (plain nut) is embedded. Due to the embedding of the pin, when installing, turning the wrench can drive the bolt to screw into the bolt ball, and at the same time, the pin slides in the sliding groove. When the bolt is screwed in place, the fastening screw is exactly in the position of the deep groove, At this point, tighten the fastening screw to allow it to fall into the deep groove, achieving the effect of stopping and preventing loosening.

 
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