Incease capacity of composite beams
Incease capacity of composite beams
(OP)
I need to increase the load carrying capacity of some of the composite beams in a typical steel framed structure. All the steel is in place and the floor is poured. I am thinking of adding a steel plate to the bottom flange of all the beams that are under consideration. Can anyone point me to specific references that might be useful for this job. Thanks in advance.
-strucguy
-strucguy






RE: Incease capacity of composite beams
As far as references go, any textbook on steel design should show you the process of composite beam design. I typically reference the Salmon and Johnson textbook.
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
What if the floor is already fully loaded?
RE: Incease capacity of composite beams
StructuralEIT -
Do you mean to say there would be no difference in plate being added to the beam with and without relieving the stresses caused due to dead load? Could you be a little bit more specific about where in AISC this has been addressed.
Thank you.
-strucguy
RE: Incease capacity of composite beams
If the full DL is applied before composite action, then it doesn't matter. The spec makes no distinction between shored or unshored construction for composite, positive flexural moment strength. See page 3-6 in AISC 360-05 under "Shored and Unshored Construction". It says, "The available flexural strength is identical for both shored and unshored construction......". The only difference is that for unshored construction you must ensure the bare steel can take the construction loads.
Strucguy-
That's right, it doesn't make a difference if the DL stresses are relieved or not. I'm making this statement strictly from a strength standpoint. There may be serviceability issues to consider.
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
All I was saying is to be mindful of the existing loading conditions. If the beams have some post-composite loads on them then that needs to be considered in the design.
RE: Incease capacity of composite beams
Dik
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
RE: Incease capacity of composite beams
make sure to check your horizontal shear so you can size the stitch welding.
RE: Incease capacity of composite beams