Concrete Floor Systems - State of the Art
Concrete Floor Systems - State of the Art
(OP)
Deltabeam came by my firm recently to promote their system...composite steel beam supporting precast hollowcore planks. Seems like a nice system, though I've never used it. Most of my concrete projects have been skip joist beam systems (66" pans) with post-tensioned girders. 21" depth usually.
So what's everyone seeing out there for concrete office or school construction? I did a biaxial voided slab system recently for a high end architect, which was interesting, but doesn't appear to be economically competitive with two-way flat plate PT or this Delatbeam hollowcore system.
Thought?
So what's everyone seeing out there for concrete office or school construction? I did a biaxial voided slab system recently for a high end architect, which was interesting, but doesn't appear to be economically competitive with two-way flat plate PT or this Delatbeam hollowcore system.
Thought?






RE: Concrete Floor Systems - State of the Art
The issue is when using a straight up material cost analysis from conventional steel supporting hollow-core to delta beam. The conventional steel option wins everytime. Delta beams are expensive.
The cost savings are in 2 major areas. 1) Depending on the size of the building you can be significantly shallower floor plates with delta beams when compared to cast-in-place or conventional steel. 2) M+E has nothing they need to bulkhead around or at least minimal bulkheading.
Point 2 is what has really sold the contractors in our area on this system. No holes through beams, no stupid bulkheads (minimal bulkheads).
There are some tricky detailing items you need to keep in mind when using the system but it doesn't detract from the effectiveness. I can get into more detail if you want but it's not required at this time I don't feel.
I should provide a caveat.... Our locale is one of the precast centres of the world. So hollow-core is super prevalent, the support structure is typically the only thing that changes (Cast-in-place, pre-cast, conventional steel, delta beams).
RE: Concrete Floor Systems - State of the Art
RE: Concrete Floor Systems - State of the Art
1) yes they can provide the fire rating however the cost of fire rated delta beams are higher than standard delta beams. Which as I indicated are higher than conventional steel in a pound for pound comparison.
The reason for this is they essentially have to neglect any contribution from the bottom flange of the beam and rely solely on reinforcement that has been welded to in the inside of the beam for the tensile resistance of the beam.
2) You still end up with the bottom flange of the delta beam showing as steel, unless the architect is expecting to apply some form of shotcrete finish to the underside of the hollow-core.
3) Architects around here love angles. This doesn't bode too well for exposed hollow-core as the cambers between adjacent panels get all messy when the supporting member is angled. If you've got nice orthagonal framing bays then it's pretty nice.
RE: Concrete Floor Systems - State of the Art
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RE: Concrete Floor Systems - State of the Art
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RE: Concrete Floor Systems - State of the Art
We completed a 22 storey tower using this. We're currently in the middle of the design phase for a 40 storey. We've done short building as well, 4 and 5 storey.
RE: Concrete Floor Systems - State of the Art
RE: Concrete Floor Systems - State of the Art
It's pretty good in all cases. Take a look at their PC corbel connectors. Keep in mind that when using wide flange columns you either need to connect to the flange, or provide a plate between flanges for the connection to occur at the outer extents of the column. This is due to the delta beam being wider than the column is deep so it will not fit between the flanges.
The other tricky detail is columns is you need to provide some form of bearing angle for the hollow-core on the side of the column. The delta beam bearing ledge stops at the face of the column.