Composite beams
Composite beams
(OP)
I am working on my first major project with composite beams. I am designing the structure as unshored. But I have some questions in my mind and I am hoping to get some input on this forum. For example,
1) What is the approximate cost of placing studs over the beam?
2) My understanding is that 3/4" is the only recommended size for use as stud per AISC 350. Is that correct?
3) I understand that the studs should project a min of 2" above the deck rib and that there should be at least 2" concrete cover over the stud. Correct?
1) What is the approximate cost of placing studs over the beam?
2) My understanding is that 3/4" is the only recommended size for use as stud per AISC 350. Is that correct?
3) I understand that the studs should project a min of 2" above the deck rib and that there should be at least 2" concrete cover over the stud. Correct?






RE: Composite beams
2) I have always used 3/4" dia studs and I don't see why you couldn't use smaller. I do not have ASIC 350 in front of me so I can't really comment.
3) According to the AISC studs are required to be placed 1-1/2" above the deck and 1/2" below the top of slab. This basically correlates to every composite deck catalog I have seen that requires 2" of cover above the flutes.
RE: Composite beams
2) stud shear connectors 3/4" or less in diameter. You could also use channels.
3) After installation studs shall extend not less than 1 1/2" above the top of the steel deck and there shall be at least 1/2" of concrete cover above the top of the installed studs.
RE: Composite beams
RE: Composite beams
RE: Composite beams
Usually the studs are spaced evenly. The only time I have seen them not spaced evenly is in regards to girders where you will have different stud counts between the locations of the point loads.... ie a girder with point loads at the 1/3 points may have an (18) (5) (18) pattern. Even the studs are spaced evenly between the point loads.
RE: Composite beams
And now I have another question. I understand that the recommended minimum composite action is 50% (base on some articles I read online). But I have some beams where the composite action is around 30-40%. what are some of the problems I could expect with a low composite action such as this.
RE: Composite beams
RE: Composite beams
With regards to the % composite action. AISC used to require a minimum 25% composite action (I believe) but they have removed that requirement for the 13th edition. I don't know about the 14th edition as I do not own one. I thought the commentary specifically addressed the removal of this limit and why they went in this direction.
RE: Composite beams