Nodal Bracing for Columns
Nodal Bracing for Columns
(OP)
Folks,
I am having a discussion with one of my senior engineers regarding the attachment of a nodal brace for a column.
The nodal brace is designed for 1% of the compression load on the column and meets the axial stiffness requirements.
My question is thus:
Does the connection from the column web to the bracing beam need to be a slip critical connection or can it be a bearing type connection with fully tightened bolts?
Even though the standard holes only have a hole diameter of 1/16 more than the bolt diameter, I am questioning whether things will be fine in the period between when the column goes into compression and then eventually into bearing at the brace?
Thanks
I am having a discussion with one of my senior engineers regarding the attachment of a nodal brace for a column.
The nodal brace is designed for 1% of the compression load on the column and meets the axial stiffness requirements.
My question is thus:
Does the connection from the column web to the bracing beam need to be a slip critical connection or can it be a bearing type connection with fully tightened bolts?
Even though the standard holes only have a hole diameter of 1/16 more than the bolt diameter, I am questioning whether things will be fine in the period between when the column goes into compression and then eventually into bearing at the brace?
Thanks






RE: Nodal Bracing for Columns
Old CA SE
RE: Nodal Bracing for Columns
I am using bearing type bolts A325 N.
In principle, I totally agree with your KISS concept. [:)]
RE: Nodal Bracing for Columns
RE: Nodal Bracing for Columns
It just changes *when* the brace starts picking up load--when the column is bent to its initial out-of-plumbness (OOP) or its OOP+1/16". The bigger its initial OOP, the bigger the brace force and stiffness required.
I don't have my seminar notes here, but I think those equations are based on an initial OOP = L/500. I guess it depends on how 1/16" compares to L/500 for your case. If the column is 30' long, the 1/16" wouldn't be adding much.
The way I look at calcs like this, right or wrong, is in the context of how closely we can actually predict what's going to happen. In a lot of cases, you could predict behavior one way versus another, go run a series of tests and who knows which method would correlate better with reality. Splitting gnat hairs?