AISC Chpater F
AISC Chpater F
(OP)
Hi Everyone,
Chapter F of the 9th Ed. AISC ASD Manual states that the equations in that section apply to ..singly or doubly symmetric beams including hybrid beams and girders ..".My understanding of this means that the equations would be applicable to built-up beams where the flanges are made of sections other than flat bar (e.g. Channels, Angles, or Tubes) as long as they are I-sections.
I am currently in a discussion with another Engineer who says that these Equations are "only applicable to standard shapes and standard built-up girders" meaning flat plated sections only. I do not see this limitation in the code and was wondering if anyone out there could shed some insight into this matter.
As long as the needs for unbraced length and compactness of the section are met as required by the code, I see no reason why the equations can not be used to calculate bending strength in a hybrid beam.
Your thoughts on this would be highly appreciated.
Thanks,
JS
Chapter F of the 9th Ed. AISC ASD Manual states that the equations in that section apply to ..singly or doubly symmetric beams including hybrid beams and girders ..".My understanding of this means that the equations would be applicable to built-up beams where the flanges are made of sections other than flat bar (e.g. Channels, Angles, or Tubes) as long as they are I-sections.
I am currently in a discussion with another Engineer who says that these Equations are "only applicable to standard shapes and standard built-up girders" meaning flat plated sections only. I do not see this limitation in the code and was wondering if anyone out there could shed some insight into this matter.
As long as the needs for unbraced length and compactness of the section are met as required by the code, I see no reason why the equations can not be used to calculate bending strength in a hybrid beam.
Your thoughts on this would be highly appreciated.
Thanks,
JS





RE: AISC Chpater F
RE: AISC Chpater F
The commentary on page 5-146 half way down even makes reference to crane girders and page 5-50 F-6 makes reference to channels.
Regards
VOD
RE: AISC Chpater F
If your section is deep then Chapter G applys for Plate Girders.
RE: AISC Chpater F
I seem to find it easy to make the connection between Chapter F and built up beams made with with Angles and Channels and I am wondering if the same would apply if the flanges were made from HSS Tubes. I think the equations would still apply as long as local buckling is adequately addressed but would like to know your thoughts on this issue as well.
Thanks.
RE: AISC Chpater F
What exactly is your application: span, loads, sizes etc? Why not use standard hot rolled sections such as plate, angles and/or channels?
RE: AISC Chpater F
RE: AISC Chpater F
The formulas are based on the Iy of each flange assuming a rectangular section, Iy=bf^3*tf/12. If the shape is going to give you a stiffness greater than this, such as a channel cap your even better. If you reinforced with a small bar at the center of the flange, then you might be in trouble. In a graduate class I had, we showed a flat plate stood on top of a wide flange could make it buckle at a lower load!
Another example of this is in coldformed channel with a lip where the lip will buckle if made too long, which will buckle the flange.