How do you align girders, beams and columns?
How do you align girders, beams and columns?
(OP)
How do you arrange columns, girder and beam? Do you align the beams with the plane of maximum moment of inertia for the columns, or do you align the girders with the plane of maximum moment of inertia for the columns?
Many -if not all- AISC documents show plan views with the beams aligned with the column's maximum moment of inertia plane, when girders transmit more shear or moment to columns. What is the logic behind that?

Rafael Guerra






RE: How do you align girders, beams and columns?
In your above picture, since there is almost no difference in the span of the girder vs. the beam, it would make sense for the girder to frame into the column strong axis.
HTH
RE: How do you align girders, beams and columns?
Mike McCann
MMC Engineering
RE: How do you align girders, beams and columns?
Thank you both for answering. Yes, what you say is what I do.
But yesterday I downloaded the Floor Framing utility from the AISC Solutions Center, and the way it works is only with the beams aligned with the columns' plane of maximum moment (or I haven't find the way to make it the other way), and that, combined with many other drawings I have seen put me to think about it.
Well, now I know I can do the job for another 5 years (LOL).
Rafael Guerra.
RE: How do you align girders, beams and columns?
Girder to column web connections are more compact (less eccentricity), can use less bolts, but may be more difficult to erect, and the girder span is slightly longer.
Girder to column flange connection simpler to erect, but eccentricity of load on column is greater, albeit on column strong axis.
Each job requires its own assessment. The edge conditions and method of lateral load resistance usually determine the column orientation.
RE: How do you align girders, beams and columns?
Framing a girder to a column flange will apply eccentricity, esp. for outer columns.
I agree with hokie66 about the determination of column orientation.
tg
RE: How do you align girders, beams and columns?
If at all possible, try to frame the girder into the column web to minimize the eccentricity of the larger load (in comparison to the single beam framing into the flange).
RE: How do you align girders, beams and columns?
Rafael Guerra.
RE: How do you align girders, beams and columns?
If using a I beam remember that it will be significantly weaker in the minor axis, therefore try using H sections.
You will have to check for lateral torsional buckling also.
Generally orientate the column so that the major axis is taking the highest loads or in the direction of the largest moment.
the formula to use is M = (e + b/2) x F
where M = Moment
e = eccentricity
b = breadth of column
F = Force (summation of shear force in a particular plane)
R. Murphy
MICE MIStructE MASCE