I am attempting to use the Joint Code check functionality of RAM Frame, and am a bit confused about implemenation, so any help would be appreciated.
From my readings of the Frame anlysis, and steel post-processor manuals/technical manuals, I though I had deduced the following:
1-Ignoring rigid end zones (in the frame/general criteria) would ignore panel zone deformation, and therefore frame stability has not been considered so AISC360-05 eqn. J10-9 would be used for panel zone shear
2a-Including effects at 0% reduction would not consider deformation and be in the same insctance as ignoring the effects.
2b-Including effects at 100% would consider deformation, and therefore J10-11 should be used.
This does not appear to be the correct understanding however, as situations 1 and 2b produce the same effect. Does anyone have any more info about this code interpretation?
Thanks.
Yes, we are now recommending that user ignore rigid end zones, using centerline analysis for the greatest flexibility in the model. We do not explicitly model the joint using 8-node quadrilateral elements.
My reading of NEHPR 4.2.1 is that if an explicit joint is modeled or centerline analysis is done, either way you can use AISC 360-05 Eq J10-11 (and J10-12).
Elastic panel zone deformation contributions to story drift can be accounted for by either explicit modeling of panel zone shear behavior [we don’t do this] or by adjusting the lengths of beams and columns in a manner that accounts implicitly for the contributions of panel zone deformations to drift [this is accomplished using centerline analysis].
Ram Connection is not getting the information from Ram Frame about whether a rigid end zone was considered or not. The check box for “Frame stability considered in analysis” is unchecked initially, and it needs to be checked for models with no REZ used in the analysis so that the Connection program will also use J10-11.
I’ll log an enhancement for that workflow to be automated (it involves a change in the data exposed through Ram DataAccess and an update for Ram Connection).
Yes, the 2009 1st edition you're quoting from does seem to allow that, between 4.2.1 and 5.4.3. However, the 2nd edition that came out last May clarifies these 2 sections, and in the process, seems to eliminate that option when using centerline modeling. For instance, 4.2.1 now says that most designers typically use centerline modeling to account for panel zone flexibility approximately, while it is also possible to explicitly model the PZ with scissor or quadrilateral elements. It then states that when this is done, J10.6 allows the increased PZ strength. When what is done? Either centerline modeling or explicit modeling? I don't think so. It goes on to say that this is "not typically done", while it started out saying that centerline modeling was typically done. So I'd interpret that as meaning the explicit modeling is what allows the use of the higher PZ strength.
Also consider the updated language in 5.4.3. There it reiterates that J10.6 allows increased PZ shear strength if if PZ deformation effects on frame stability are considered, which can be approximate or explicit. And it specifies that this means using equations J10-11 & 12 in lieu of J10-9 & 10. But the next 2 sentences are, "If panel zones are explicitly modeled in the analysis, it is permissible to use these equations. However, as explained in Section 4.2.1, this is not common."
The authors seem to be tying Equations J10-11 & 12 specifically to explicit scissor or quadrilateral element panel zone modeling. And if that's the case, I don't think y'all (or most of us) would ever be able to use the higher strength equations.