temperature vs bending reinforcement
temperature vs bending reinforcement
(OP)
Hi guys,
when analysing a slab versus temperature, do u consider the enveloppe of the reinforcement required for temp and the one needed for bending or the addition should be considered?
In the paper written by Gilbert (the aci refers to this paper), It clearly states that the enveloppe should be considered while ACI in its proposed combinations, adds the effect of T to the gravity loads!
what is ur practise ?
thanks :)
when analysing a slab versus temperature, do u consider the enveloppe of the reinforcement required for temp and the one needed for bending or the addition should be considered?
In the paper written by Gilbert (the aci refers to this paper), It clearly states that the enveloppe should be considered while ACI in its proposed combinations, adds the effect of T to the gravity loads!
what is ur practise ?
thanks :)





RE: temperature vs bending reinforcement
There is also the requirement for shrinkage and temperature reinforcement. This is normally a minimum reinforcement to control restraint stresses in the concrete and is not normally added to the ultimate reinforcement.
RE: temperature vs bending reinforcement
Minimum flexural reinforcement is (currently) found in ACI 318-11 10.5. This value tries to make sure there is not catastrophic failure at the moment the slab cracks and all load transfers to the reinforcement. It also acts similar to T&S reinforcement.
Shrinkage and temperature reinforcement is transverse to flexural reinforcement, and requirements are found in 318-11 7.12.
As Rapt said, they are not added in the same direction. For some applications, you may want to use additional T&S on the face of a slab opposite the flexural reinforcement for serviceability or appearance (crack control) reasons.
RE: temperature vs bending reinforcement
we are studying a case where the slab will be cast and no shrinkage strip is allowed.
thanks
RE: temperature vs bending reinforcement
Is the slab prestressed?
RE: temperature vs bending reinforcement
Personally, i think, for such kind of elements, a shrinkage analysis should be done but it should be added to construction loads (say 150kg/m2 SDL and 200 kg/m2 LL). 2nd Analysis should be done for gravity loads (during life of the structure) and the enveloppe should be adopted since 60to 70% of the shrinkage must have been finished before service conditions. Temperature isn't a problem since the slab in question is located below ground. Therefore, no temperature is there (except some differential one between top and bottom fiber). :)
RE: temperature vs bending reinforcement
You would have to do the section design for a combination of the bending stress and the shrinkage restraint induced strains and come up with a momnet/curvature profile for the section including both effects.
To siomply add the requirements for both effects calculated separately would be very conservative.
RE: temperature vs bending reinforcement
RE: temperature vs bending reinforcement
If you start adding reinforcement, be sure flexural members are still tension-controlled.
As I mentioned previously, shrinkage and temperature steel is only required in orthagonal directions to flexural reinforcement, since flexural reinforcement and the associated compression on the opposite face will negate the need for T&S. The minimum amount of flexural steel is the same as the minimum for T&S.
RE: temperature vs bending reinforcement
2- U can't count just on the flexural reinforcement to control the cracks due to temperature and shrinkage since when significant restraint is there, amount of reinforcement requierd for T&S may exceed the one required for bending.
regards