MINIMUM REINFORCEMENT
MINIMUM REINFORCEMENT
(OP)
For the design of water tank walls,
Do we need to COMBINE minimum steel required for 1.) Shrinkage & Temperature and 2.) Flexural or we pick minimum steel required based on whichever case is governing(S&T or Flexure)?
Do we need to COMBINE minimum steel required for 1.) Shrinkage & Temperature and 2.) Flexural or we pick minimum steel required based on whichever case is governing(S&T or Flexure)?






RE: MINIMUM REINFORCEMENT
Kieran
RE: MINIMUM REINFORCEMENT
We are Virginia Tech
Go HOKIES
RE: MINIMUM REINFORCEMENT
Make sure you go through the wall provisions (Ch. 14 in ACI), as the minimum requirements are different from flexural.
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
Can anyone explain WHY WE DO NOT COMBINE the steel reqd. for S&T and Flexure?
Assuming we provided steel based on flexural requirement which is more than required for S &T.
Do the Shrinkage occurs during 7-10 days of casting when there is no loading, so steel will see S & T stresses only and by the time the structure see actual loads and experience flexural stress, the S&T stresses are already gone or very minimal?
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
I'm talking off the cuff here. But, I think the idea is that for slabs and tanks and such, you need to limit the crack widths parallel to the flexural steel in order for the flexural steel to be effective. Make sense?
In that sense, the flexure and the T/S are not occuring at the same time in the same direction for the same piece of steel.
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
I am unsure whether ACI has similar provisions.
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
Can you explain more on "flexural steel can be considered part of the requirement for minimum shrinkage and temperature reinforcement."
So if we need say 0.25 inch²/ft minimum for flexure and 0.1 inch²/ft minimum for direct tension, then in total we need to have 0.35 inch²/ft on any face at all times or not?
RE: MINIMUM REINFORCEMENT
It depends on whether you have a temperature/shrinkage load that you have to design for, or if you are simply looking at minimum shrinkage and temperature reinfrocement.
If you have specific defined loading that you have to allow for, then it has to be combinded with the flexure loading in calculating the reinforcement requirements. This is often the case with concrete tanks.
In the cases people are talking about above, they are discussing basically a minimum reinfrocement requirement 9S&T) versus a strength requireemnt. If the strength requirement is smaller than the minimum S&T requirement, then you use the larger value.
If you have a water pressure moment plus a shrinkage/temerature moment, then they need to be combined if they can act at the same time to get the worst result.
RE: MINIMUM REINFORCEMENT
RE: MINIMUM REINFORCEMENT
Thanks. That's the reply I was looking for.