Attached is a screenshot from a delegated connection design I am currently working on.This is a W12x40 column with a W21x50 beam framing into the column web at the 2nd floor. In checking it for a 32k shear reaction, and a 41k axial load (ASD), RAM Connection shows this passing with a utilization ratio of 78% (bolt shear governing). Note: I wouldn't normally do a shear tab like this with bolts inside the column flanges, but I'm checking some connections as already detailed and fabbed. Since these are already fabbed this way, it would be great if RAM Connection was correct that it worked like this, especially since there are several cases of axial loads on column web connections on this project, at drag struts and at braced frame connections. RAM Connection claims to check connections per AISC 360-16, but one of the more notable changes in the 2016 spec was the addition of checking for out-of-plane loading of plate elements such as column webs via J10.10 of the spec, and pages 9-14 through 9-17 in the 15th edition steel manual. No check of the column web for the beam axial load is noted in the RAM Connection output, even when AISC 360-16 is selected as the design code. Checking the connection in a competing connection software that is finite-element-based, the column web is shown to fail massively (2nd screenshot). Hand-checking the column web capacity for the beam axial load per AISC Equation 9-31 shows a max load of 13.9 kips, or 1/3 of the applied load (3rd screenshot). Since this check is required in AISC 360-16, and Bentley claims to be in conformance with the 2016 provisions, why does RAM Connection show this passing with a 78% strength ratio instead of failing with a ratio of 295% like AISC indicates?
Thanks,
Jason
Yeah, chord wall plastification has been part of the checks on HSS in AISC and in RAM for years. This long overdue addition to 360-16 just recognizes that there's little difference in limit state between the HSS wall and a W-column web under the same out-of-plane load. I would've called it a defect instead of an enhancement since it seems a little premature to claim that RAM complies with 360-16 checks while leaving that significant check out, but however it gets addressed, I'll be happy when it does get incorporated.
It looks like the only support side code check we are performing in the single plate - BCW connection is a weld rupture check. AISC 360-16 "Plate Elements Subjected to Out-of-plane Loads" would have to be added. Chord wall plastification is being checked when using an HSS column, however. (Enhancement 1003068)
Answer Verified By: Jason McCool