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I know that the minimum number of reinforcement bars in circular concrete section of columns are 6, is it the same for circular tie rod section?

Samir Benabdelaziz
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  • You have to offer more info on the tie rod, its purpose, size...etc Usually tie rod is single steel encase in the protective material, mainly used for tension. – r13 Jun 03 '22 at 16:13
  • what i mean by Tie Rod is reinforced concrete column subjected to pure tension, so the cross section of this element is circular – Samir Benabdelaziz Jun 03 '22 at 16:22

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if you mean a square section with circular or spiral ties, even though it is very uncommon for such a section to be built, I would put 6 bars.

kamran
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The longitudinal reinforcement in a concrete column serves two functions - 1) to provide the required strength to resist the applied forces, and 2) acting as support for the transverse reinforcement (hoops/ties). The reason for the minimum reinforcement requirement is based on the latter, because, in general, a column is a compression member, for which the shear stress and buckling are the main concerns, which can be minimized/eliminated by providing the minimum amount of stress confining reinforcement - longitudinal bars and hoops (for circular columns).

If a column is mainly provided to resist tension, as tension ties/piles, the former reasons for requiring the minimum reinforcement are no longer exist, instead, you shall provide reinforcing with minimizing the potential cracks in mind, for which, there is no guidance exists, but to exercise by the engineering judgment at a case by case base - a single steel rod encased in the concrete protective layer is acceptable in the non-corrosive environment, but more bars are needed otherwise.

r13
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  • FYI - Canadian Highway Bridge Design Code (CHBDC) and American Railway Engineering and Maintenance-of-Way Association (AREMA) Manuals both provide a cracking strength for concrete. One could provide sufficient reinforcing steel such that the cracking stress in not reached. I believe is was CHBDC 2014 also had some clauses for designing rebar to limit crack sizes as well. The CHBDC 2019 has redesigned those clauses so they no longer directly appear as crack limitation. – Forward Ed Jun 05 '22 at 19:37
  • @ForwardEd There is no shortage of methods to minimize the cracks and crack width, all depend on the environment and exposure factors. We know that all concrete cracks, but not all require extensive crack control measures. When applying code provisions, we need to know the intents. – r13 Jun 05 '22 at 20:21