Design method of tensile-shear composite stress for high-strength bolted connection with end plate tapping

Aiming at the composite stress and deformation characteristics of high-strength bolted connection with end plate tapping, the interlock mechanism between the end plate tapping and high-strength bolt threads was investigated. Monotonic loading tests and finite element parametric analyses were conducted on the connections with single bolt in different tension-shear ratios to figure out the influences of end plate tapping thickness, bolt characteristics, and the angle between the friction plane and tensile loading on the bearing capacity of the connection. The test results indicate that, in the tensile loading tests, the bearing capacity and deformation of the high-strength bolt connection with end plate tapping are consistent with those of the traditional bolt connection. In the shear loading tests, the screw in the M20 high-strength bolt connection with end plate tapping can still be cut off when the thickness of the end plate reaches 16 mm, while the tapped threads inside the end plate hole remain small deformation and the threaded plates slip slightly in the early loading stage. In the tensile-shear loading tests, the failure mode of high-strength bolt connection with end plate tapping transfers from shear failure to tension failure with the increase of the angle between the friction plane and tensile loading from 30° to 60°. The parametric analyses reveal that the critical angle of the high-strength bolt connection with end plate tapping is between 45° and 52. 5° for the connection failure from shear to tension. The design curves of the bearing capacity of the fiction type high-strength bolt connection and the compression type high-strength bolt connection in the tension-shear composite loading were developed. The bearing capacity of the friction type connection can be calculated following the current standard, while the design equation for the bearing capacity of the compression type connection was developed with the introduction of bearing capacity correction factors for tension and shear, respectively, which can provide reference for engineering design. © 2024 Science Press. All rights reserved.