3.4 bolts and threaded parts

In bolts and threaded parts, the range of stress of the applied cyclic load shall not exceed the allowable stress range computed as follows.

(a) For mechanically fastened connections loaded in shear, the maximum range of stress in the connected material of the applied cyclic load shall not exceed the allowable stress range computed using Equation A-3-1 or A-3-1M, where $C_{f}$ and $F_{T H}$ are taken from Section 2 of Table A-3.1.
(b) For high-strength bolts, common bolts, threaded anchor rods, and hanger rods with cut, ground, or rolled threads, the maximum range of tensile stress on the net tensile area from applied axial load and moment plus load due to prying action shall not exceed the allowable stress range computed using Equation A-3-1 or A-3-1M, where $C_{f}$ and $F_{T H}$ are taken from Case 8.5 (stress category G). The net area in tension, $A_{t}$ , is given by Equation A-3-7 or A-3-7M.

A_{t}=\frac{\pi}{4}\left(d_{b}-\frac{0.9743}{n}\right)^{2}

(A-3-7)

A_{t}=\frac{\pi}{4}\left(d_{b}-0.9382 p\right)^{2}

(A-3-7M)

where

db = nominal diameter (body or shank diameter), in. (mm)

$n \quad=$ threads per in. (per mm)
p = pitch, in. per thread (mm per thread)

For joints in which the material within the grip is not limited to steel or joints that are not tensioned to the requirements of Table J3.1 or J3.1M, all axial load and moment applied to the joint plus effects of any prying action shall be assumed to be carried exclusively by the bolts or rods.

For joints in which the material within the grip is limited to steel and which are pretensioned to the requirements of Table J3.1 or J3.1M, an analysis of the relative stiffness of the connected parts and bolts is permitted to be used to determine the tensile stress range in the pretensioned bolts due to the total applied cyclic load and moment, plus effects of any prying action. Alternatively, the stress range in the bolts shall be assumed to be equal to the stress on the net tensile area due to 20% of the absolute value of the applied cyclic axial load and moment from dead, live, and other loads.

User Note: Where provisions of this Specification differ from provisions of the RCSC Specification for Structural Joints Using High-Strength Bolts or the AWS Welding Code—Steel (AWS D1.1/D1.1M), the provisions of this Specification govern. Some differences between this Specification and the RCSC Specification related to fatigue are described in the Commentary.

3.4bolts and threaded parts