Composite Steel beam
Composite Steel beam
(OP)
So it's 1957, not that long ago.
It's a floor beam W21x68 with 1"x1"x8" long square steel studs welded to the top flange of the steel beam, center of flange only. The concrete floor slab is 9" thick and actually the beam is completely encased in concrete. The studs are variously spaced @ 6"o.c. for the first 6 feet, then 9" for the next 3 feet and then finally 12"o.c. for the next 3 feet from each end.
Question is where can one find some information to determine what capacity the composite beam has and what was the design basis at the time?
Thanks.
It's a floor beam W21x68 with 1"x1"x8" long square steel studs welded to the top flange of the steel beam, center of flange only. The concrete floor slab is 9" thick and actually the beam is completely encased in concrete. The studs are variously spaced @ 6"o.c. for the first 6 feet, then 9" for the next 3 feet and then finally 12"o.c. for the next 3 feet from each end.
Question is where can one find some information to determine what capacity the composite beam has and what was the design basis at the time?
Thanks.






RE: Composite Steel beam
8" long ??
are they merely spacers ? contact pads ??
RE: Composite Steel beam
RE: Composite Steel beam
maybe (probably ?) i'm missing something ??
RE: Composite Steel beam
RE: Composite Steel beam
La Estructura Metálica Hoy, 2nd ed.
Ramón Arguelles
Librería Técnica Bellisco, Madrid 1975
it seems comes from DIN codes support.
attached in 2 jpgs (spanish)
RE: Composite Steel beam
RE: Composite Steel beam
RE: Composite Steel beam
I have another text of the era common here for composite beams, and may try to see tomorrow if the thing is treated.
RE: Composite Steel beam
I wouldn't be too concerned about lack of the head, as I can't see the slab lifting off the beam, especially with the beam being encased. If the beam were encased per the Specification requirements at the time, shear connectors would not have been required at all. However, this requirement stated that the top of the steel had to be 2" above the slab soffit, and that is not the case here.
I think the only issue is how well the bars are welded to the beam. If welded competently, I think the beam would be fully composite. Partially composite was not talked about in those days, and the amount of studs quoted would be more than required today for fully composite action for most spans.
RE: Composite Steel beam
In a sideways shear load (any direction), won't that long of a "square stud" bend - thus breaking the concrete to "square stud" joint?
RE: Composite Steel beam
I guess the next question will be has anybody seen this type of construction in a North American Code or standard from this time.
My thoughts immediately are; how can the 1"x 1" block transfer shear flow? in the face of, (pun the lowest form of humour), 3/4" aggregate, and if it can, how effective can it be? And how does one arrive at an effective concrete slab (flange) width, beff, b1? Do we actually have composite action going on here?
The new application involves putting a new cooling tower on top of these beams/floor slabs, re new concentrated point loads now along the beams length vs a udl load as it previously was a water cooling basin/pond/tank/pool, with no concentrated load demand on the composite? beam/floor slab.
I particularily enjoy working on structures of this vintage and earlier. By all applications of engineering principles and current codes, they shouldn't be standing.
RE: Composite Steel beam
if they are vertical, then i think they'd be less efffective.
maybe, if they are exposed on the concrete face, they're there to show where the beam is, and as a contact pad.
RE: Composite Steel beam
Estructuras Mixtas, Teoría y Práctica
Julio Martínez Calzón
Instituto Eduardo Torroja de la Construcción y del Cemento
Madrid, 1966
again in two jpg pages
RE: Composite Steel beam
RE: Composite Steel beam
rb1957,
Sounds like you need a primer on steel and concrete composite construction.
RE: Composite Steel beam
i guess the subtext is "if you don't know, don't post ..."
RE: Composite Steel beam
I've seen a number of differnt steel joist companies get into composite joist systems by relying on various non-standard ways of transferring this shear.... Friction on a roughed steel surface. Bent plate parallel to top chord. Granted, they then have to back up their calculations with test data. However, this system seems way more conventional than these other ones that are being used on modern projects.
RE: Composite Steel beam