CONCRETE BEAM CAMBER
CONCRETE BEAM CAMBER
(OP)
I would like to know if there are any publications addressing this issue? Thanks.
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RE: CONCRETE BEAM CAMBER
RE: CONCRETE BEAM CAMBER
RE: CONCRETE BEAM CAMBER
Camber does not reduce the total deflection, only the "seen" deflection.
Remember that anything attached to the member being cambered will not benifit from the camber. The total deflection from the poured position will still be the same as for a non-camber member. The only difference is the amount of deflection above or below the horizontal.
If curtain walls are being attached or brittle partitions such as brick walls or brittle finishes placed on the member, camber will not help at all in reducing the deflection that the attached materials experience.
Camber is only useful for members such as parking garage beams where it may be desirable to reduce the amount of deflection that can be "seen" i.e. the deflection from the horizontal. By cambering by half of the total expected deflection then the "seen" deflection will only be half of the deflection, but the total deflection is still the same, just measured from a different starting level.
RE: CONCRETE BEAM CAMBER
RE: CONCRETE BEAM CAMBER
Floors in occupied buildings should be fairly flat under self-weight so that cabinets, walls, etc. will be able to sit square. A flat roof should be cambered where there is concern that long-term deflections (creep in concrete for instance) can expose your structure to ponding. Cambering beams that receive a subsequent concrete deck helps avoid extra thick slabs at midspan due to finishing the concrete flat...thus avoiding excessive dead loads and loss of safety factor.
Cambering isn't something that you do every day, but it isn't just for looks.
RE: CONCRETE BEAM CAMBER
I am simply stating what many forget about cambering. Explaining the limitations. You did not mention it in your response. The person you were answering might not have realised it and could get into trouble because of it.
I have seen examples where unthinking designers have not realised this. Someone who designs a 15m span slab edge which will deflect over 110mm so they specify a precamber of 90mm and think they have designed a nice relatively flat slab with only 20mm deflection over 15000mm. Then they connect a glass curtain wall to it. OOPS.
Same thing with your office space. Deflections after camber look ok, still hogging upwards under initial self weight. Until they erect lots of stiff (but not brittle) partitions and, as the slab deflects due to cracking, shrinkage, creep etc, we have nice gaps at the bottom or the top of the partitions , depending on whether or not the partition man bolted them to the floor, and the doors do not close properly. All because the designer thought he was only going to get 10mm or 20mm deflection and ended up with 120mm.
Yes, camber has it's uses but we must understand its limitations. Properly designed non-cambered PT members perform much better than cambered RC members in terms of deflection control.
RE: CONCRETE BEAM CAMBER
RE: CONCRETE BEAM CAMBER
Depending on your definition of "levelled", this is not possible for a suspended slab.
You need to get the Mobile Shelf supplier to give you more realistic limitations, or tell him it is not possible. Precamber cannot help you and neither can prestress. You cannot avoid live load, shrinkage, creep and temperature deflection, after the slab is poured and stripped, no matter what suspended structural system you use.
You only solution is a slab on ground and you will have to support it on rock, not soil of any sort. Then you might have a chance of complying.
The concretors cannot even finish the slab surface to comply with this, forgetting about deflections.
RE: CONCRETE BEAM CAMBER
Carl Bauer
www.bauerconsultbotswana.com
RE: CONCRETE BEAM CAMBER
RE: CONCRETE BEAM CAMBER