huangyhg

concrete slab on metal decking
is only anticracking reinforcement specified for these slabs? my problem is a steel building was purchased and the concrete slab and reinforcement were not specified for the metal pan decking. i have no literature on how to design such (one way) slabs . the span is 8 ft so i estimate that 6" max depth slab 4000psi reinforced one layer of a193 mesh placed 1 " above the crests of the metal decking would be more than adequate.
please provide some guidance. thanks.
check out our whitepaper library.
two points:
1) i'm assuming you're using composite decking. even so, we never trusted the composite action, and added regular reinforcing (temperature and bending) whenever we used it.
2) check your construction case. an eight foot span without shoring might not support the wet weight of six inches of concrete. if it can't, you probably should remind the contractor to shore the metal deck.
spans/load capacity vary with slab thickness, reinforcement, deck depth, and deck gauge, for both composite deck and form deck. a composite deck/slab and beam/joist system also has shear studs (size and number) to consider.
get a reference on designing it properly. vulcraft will send you a free copy of their "steel roof and floor deck" design manual, which is very good and has all the information you need, including tables, specs, details and sample calculations.
jedclampett,
we have design hundreds of buildings using composite metal deck (2" 20 gauge as the standard) with 10 foot spans with not a single problem. these buildings are used for manufacturing, office, sensitive equipment, etc. i think adding deformed steel to a composite slab is being too conservative.
for what its worth
i agree with dougantholz providing deformed steel with the metal deck is way to conservative. the topping steel provided has to satisfy the horizontal forces necessary for robustness and diaphram action as well as anti-cracking.
kieran
dougantholz,
for typical office floors, i agree with you - the composite deck itself is adequate tension reinforcing. however, some deck manufacturers warn that you should provide separate reinforcing for applications such as vehicular traffic or vibratory loads where there is a possibility of the concrete delaminating from the deck.
if designed with the span/load limits as per a deck manufacturer, you're probably not ever going to need rebar. but, as jedclampett says, during construction, you may have excessive deflection. even this, though, is covered in manufacturer's design manuals.
the one time you may need rebar, is in designing for diaphragm action, especially with a long narrow floor that is not adequately connected to the supporting steel framimg for enough shear.
hope this helps...
ven2002 (visitor)24 aug 02 13:48
excuse me again. now i understand better your questions. your require to design slabs concrete with corrugated steel deck, i understood other thing. it is better to contact boock store of steel deck institute or producer companies.
dougantholz and others,
what do you do about strength design for fire resistance in you provide no bonded reinforcing steel?
rapt,
i'm not sure i understand your question. do you want to know what is done for strength design and fire resistant rating? or is you question related to strength design with a fire/high temperature application?
please clarify - and maybe start a thread.

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