Chapter 3 - Tension Members
© 2006, 2007, 2008, 2011 T. Bartlett Quimby
Tensile Yielding & Tensile Rupture of Connecting Elements
Last Revised: 07/30/2011
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. As a result of this behavior, the SCM treats these short connecting tension elements slightly different than normal tension members. Figure 3.5.1 shows splice plates being used to transfer force between two wide flange sections. Each splice plate is tension member.
You will find the requirements for connecting elements in SCM J4 (SCM page 16.1-128)
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 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.
The Essential Difference
There is really only one significant computational difference between short connecting tension elements and tension members. In the case of short connecting elements, An is computed as previously described then compared to 0.85Ag. If the computed valued of Ae exceeds 0.85Ag then An is assigned the value 0.85Ag. For the case of short connecting elements, U generally equals 1.0 since the entire connecting element is used to transfer force so this means that Ae = An. This requirement accounts for the short full tension length of the member.
Sample Spreadsheet Calculations
The spreadsheet calculation provided in section 3.4 for tensile rupture handles both tension members and short connecting tensile elements. If the user indicates (in the appropriate cell) that the member is a connecting element, then An is the minimum of the An resulting from the failure path analysis and 0.85Ag.