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Section 3.5
Tensile Yielding & Tensile Rupture of Connecting Elements
Last Revised: 04/11/2021
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Figure 3.5.1 |
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Connecting elements are tension members that have a very short distance between the end connection regions and are generally used to connect two or members together. In these cases, there is not much length for redistribution of forces since the tensile yielding region is so short. Figure 3.5.1 shows splice plates being used to transfer force between two wide flange sections. Each splice plate is tension member in its own right and the provisions of SCM J4 apply to their analysis and design.
You will find the requirements for connecting elements in SCM J4 (SCM page 16.1-137)
SCM Chapter J deals with all things related to connections. We will be spending some more time in this section over the next few chapters. For now, we will concentrate on SCM J4.
The method for determining the tensile strength (both yielding and rupture) for connecting elements is found in SCM J4.1. You will notice that the equations are essentially the same as for other tension members with the exception that there is an upper limit to Ae for bolted splice plates.
SCM D2 vs SCM J4.1
In the prior editions of the Specification, SCM J4.1 put an upper limit on the value of An for bolted splice plates. That requirement has been removed in the 15th edition of the SCM, removing the only significant computational difference between SCM J4.1 and SCM D2. For the case of short splice plates, U generally equals 1.0 since the entire connecting element is used to transfer force so this means that Ae = An.
SCM J4.1 does have a note stating that "the effective net area may be limited due to stress distribution as calculated by methods such as the Whitmore section." This note constitutes the only significant difference between SCM D2 and SCM J4.1. The Whitmore section is a computation technique developed to determine the strength of gusset plates that are typically used to connect bracing elements to beams and columns. SCM Part 9 (SCM page 9-3) gives a brief description of the computation of a Whitmore section and when to use it. For the case shown in Figure 3.5.1, the Whitmore section is not applicable.
Sample Spreadsheet Calculations
The spreadsheet calculation provided in section 3.4 for tensile rupture handles both tension members and short connecting tensile elements.