Recommended composite action (25% vs 50%)
Recommended composite action (25% vs 50%)
(OP)
I am a little unclear about the history of the recommended composite action for composite steel beams. I have heard that 25% is the “new” recommended minimum and that it used to be 50%. I haven’t been around long enough to know the history so if someone can take a few moments and bring me up to speed that would be very helpful.
Also,
1) What are some of the ways to increase the composite action in a beam (silly question I am sure)?
2) Can you use a continuous or cantilevered beam as a composite. I think the anwer is no but I could be wrong.
Thanks.
Also,
1) What are some of the ways to increase the composite action in a beam (silly question I am sure)?
2) Can you use a continuous or cantilevered beam as a composite. I think the anwer is no but I could be wrong.
Thanks.






RE: Recommended composite action (25% vs 50%)
AISC Tables for composite beams go down to 25% and it is therefore the De facto minimum that many people use as well as software vendors.
The AISC Commentary cautions against using less than 50% due to premature departure from elastic behavior and increased ductility demands on the studs, but this is only Commentary.
I have found around 40% to be the sweet spot for economy, which generally works out to be a stud a foot.
1) Read AISC Chapter I. 2) Read the Commentary to AISC Chapter I.
RE: Recommended composite action (25% vs 50%)
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Recommended composite action (25% vs 50%)
RE: Recommended composite action (25% vs 50%)
RE: Recommended composite action (25% vs 50%)
Dik
RE: Recommended composite action (25% vs 50%)
I know an old-timer who doesn't space shear studs further than 12 inches on center. I wonder if this is what is he going for with that rule.
RE: Recommended composite action (25% vs 50%)
RE: Recommended composite action (25% vs 50%)
1) what is the ideal % action that one should try to achieve?
2) Can you get 100% composite action?
3) For girders, supporting 2-3 beams, could you use two rows of studs?
RE: Recommended composite action (25% vs 50%)
The ideal percentage differs from region to region and from beam to beam. You have to add more studs to get a higher % composite. So, it's a matter of how much steel costs per pound compared to the installed cost of adding studs.
To get to 100% composite action all you need to do is add more studs (usually). And, girders can certainly have multiple studs per deck flute.