11.4.5 - Spacing Limits for shear reinforcement
11.4.5 - Spacing Limits for shear reinforcement
(OP)
I have an 18" square concrete column that has very little uplift and shear forces (couple kips). According to section 11.4.5.1 in 318-08 taking d/2 would require tie spacing of 7" c-c. This seams excessive as I normally see these ties spaced at 16" c-c. Could anyone provide more insight or is the d/2 pretty solid?





RE: 11.4.5 - Spacing Limits for shear reinforcement
RE: 11.4.5 - Spacing Limits for shear reinforcement
1. If the shear Vu is greater than φVc then you must provide shear stirrups based on Equation 11-2 and Section 11.4.7 (i.e. Vs is calculated)
2. If the shear Vu is greater than φVc/2 but less than φVc, then you must meet 11.4.5 (your stated situation)
3. If the shear Vu is less than φVc/2 no shear reinforcement is required. (based on 11.4.6.1)
So if you are under condition 3 above, then you can essentially do what you like - providing ties or whatever to facilitate construction or to give you a level of warm fuzzies.
If you are in condition 2, then yes - you must meet the limits in 11.4.5.
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RE: 11.4.5 - Spacing Limits for shear reinforcement
JAE: With such low Vu values I thought shear ties would be more to facilitate construction/warm fuzzies also, but when I read 11.4.5.1 it seemed to be saying these are minimum spacing regardless of shear values. Thanks for your post made much sense and now am able to rationaliz vs tossing extra ties at the column.
RE: 11.4.5 - Spacing Limits for shear reinforcement
RE: 11.4.5 - Spacing Limits for shear reinforcement
They put it there to trick you.