CJP Splice #2

[puy]

In thread507-224841 nutte & civilperson indicated that a beam moment connection where flanges of the beam are welded using a CJP should have the same capacity as the original section.

However, in order to install the CJP a small section of the web is removed to provide the "rat holes". These are small spaces below the flanges to allow access for the installation of the CJP continuously over the web of the beam.

This length of these "rat holes" web sections at the root of the flange typically are +/- 1" (or t_f + 1/2").

After the CJP welds for the flanges are installed, I understand the flanges sections can be assumed to be continuous with the supporting element. However, the web of the beam will have between 1" and 2" missing at the base of the flanges.

Is it safe to assume a moment connection, that uses CJP welds for the top and bottom flanges has the same capacity of the full beam section when specifying this type of connections?

(If so, please provide reference or indicate if it is customary)

Or should the capacity of the connection be based on the actual beam section by substracting the rat hole opening? (Please note de difference in S_x ranges from 4% to about 8% depending on the size of the section)

 

[KootK]

nutte & civilperson indicated that a beam moment connection where flanges of the beam are welded using a CJP should have the same capacity as the original section.

I'm not sure that this is an accurate interpretation. Unless you're doing high seismic plastic hinge design, or perhaps a fatigue sensitive design, you only need to develop the capacity to meet your expected moment demand resulting from applied loads. Moment connections where there is only a shear connection at the web are common.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[WillisV]

http://msc.aisc.org/globalassets/modern-steel/steelwise/052012_steelwise.pdf