load applied to lower flange of beam
load applied to lower flange of beam
(OP)
I am a new entrant to the forum.
I have been puzzling over the following:
Why are loads always applied to the top flange of beams?
Is the capacity lowered if the loads are applied internally to the lower flange?
I have been puzzling over the following:
Why are loads always applied to the top flange of beams?
Is the capacity lowered if the loads are applied internally to the lower flange?






RE: load applied to lower flange of beam
Over the years as much flooring was designed as concrete slab on steel beam and the connections from the beams to the columns were generally easier to make with the beam external to the slab it just became normal practice.
There is some help for the steel beam from the concrete floor above in that the floor slab helps brace the compression flange (usually the top flange in simple beam connections) of the beam. This helps prevent a premature failure due to buckling rather than allow the beam to develop its full strength.
As for loading the bottom flange - its is done as industry requires. For example overhead cranes for use in industrial warehouses run along the "bottom" flange of a beam. There are also many applications where a load must be permanently affixed to the bottom of a beam.
RE: load applied to lower flange of beam
This is ascertained through proper use of Cb and equivalent procedures. You can read about this on Galambos V edition.
RE: load applied to lower flange of beam
I tend to apply loads to edge beams through the top flange and through the bottom flange on internal beams to limit the downstands
Kieran Coyle
BEng(hons),CEng, M.I.Struct.E, M.I.E.I.
RE: load applied to lower flange of beam
Your thoughts have been very helpful
I shall be back
JEG
RE: load applied to lower flange of beam
It should be noted also that there are some specific loading conditions in which the lower flange is directly loaded, such as the bolting of monorails beams to the underside of support girders/beams. In these cases, the beam capacity can be diminished if:
1. The percentage reduction of the flange cross section at the bolt holes is greater than that allowed by the applicable steel code.
2. The local flange bending should also be looked at, and gussets added if necessary.
Hope this helps,