Strut and Tie
Strut and Tie
(OP)
I have an easy question. In a strut and tie design does the maximum shear limit of ACI 318 11.7 still apply?
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RE: Strut and Tie
RE: Strut and Tie
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Strut and Tie
RE: Strut and Tie
RE: Strut and Tie
RE: Strut and Tie
RE: Strut and Tie
- I agree that a literal read of 11.7 would lead one to apply 11.7.3.
- I agree that 11.7.3 seems like a reasonable upper limit and I would be surprised to see it govern in any properly STM designed members.
- my suspicion is that 11.7.3 exists for the benefit of deep beam design procedures other than STM.
- 11.7.2 language kind of implies that 11.7.3 could be skipped for STM designed members.
- 11.7.3 commentary contends that we're guarding against diagonal compression failure. But then the form of the equation suggests that we're checking concrete tensile stresses. Does concrete tensile stress have a major role to play in STM designed members? Maybe it is getting at cross strut tensile splitting stresses? But then I thought that the whole idea was to allow diagonal tension cracking and keep the crack width reasonable using side face reinforcement?
In answer to OP's original question, I guess that I'd put it in functional terms:
1) in a new, minimally constrained design, would I ensure that 11.7.3 was satisfied? You bet.
2) If sasisfying 11.7.3 required a post-tender adjustment or potentially agravating a client, would I let it slide? Probably.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.