Steel beams supporting hollow core
Steel beams supporting hollow core
(OP)
The architect has asked me for an alternate design for the standard composite metal deck framing.
I have a floor system consisting of hollow core plank bearing on steel beams. Can the steel beams be considered composite if I size headed studs on them?
Thank you!
I have a floor system consisting of hollow core plank bearing on steel beams. Can the steel beams be considered composite if I size headed studs on them?
Thank you!






RE: Steel beams supporting hollow core
RE: Steel beams supporting hollow core
RE: Steel beams supporting hollow core
RE: Steel beams supporting hollow core
Another semi related issue is that the hollowcore can continue to shorten under the prestressing force (via creep/shrinkage mechanisms), this means a crack can form at the end of the unit which means that the limited concrete around the stud between two units on either side of the beam is unconfined by the units, so it's like putting studs right on the edge of a free slab edge and there is a corresponding reduction to stud capacity.
You have to really go back to first principles in terms of fundamental stud behaviour, a good text that explains the fundamentals is
Oehler, D.J. and Bradford, M.A. (1995). “Composite Steel and
Concrete Structural Members – Fundamental Behaviour.” 1st
edn Elsevier Science.
Also I've found to suppress brittle failure modes, such as longitudinal splitting you really needs two studs across the flanges, this pretty much ensures the studs can yield prior to splitting (because you cannot get any post splitting reinforcement in where it's required this the only ductile mechanism for failure of the studs). We also put about 33% more studs than required (it's based on some statistics around only having the one failure mechanism) and it helps us sleep at night!
Good luck.
RE: Steel beams supporting hollow core
RE: Steel beams supporting hollow core
Where do the studs go? I assume in the joint between slabs which are grouted, but that seems an onerous and unrealistic coordination job.
RE: Steel beams supporting hollow core
Jason McKee
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RE: Steel beams supporting hollow core
RE: Steel beams supporting hollow core
We also are required to feed bars into the core and concrete fill at least 2 cores 800mm per unit in this part of the world to address some of the issues cooperDBM is referencing. We've had to do this for 10 plus years, mainly to address frame elongation issues which can cause a loss of seating & the end of the units to fail due to insufficient development of the strands right at the ends of the units.
It's important to check the longitudinal shear, especially if your studs don't extend above the hollowcore. You may need some stirrups in the gap between the units that extend into the topping. Check multiple critical planes, not just the thinnest topping section at the ends of the unit. If you have sufficient space between the units you can run some larger bars along the beam at the base of the studs to enhance the longitudinal shear capacity. We often drop some 25mm bars in here to enhance the capacity in longer more heavily loaded spans.