How does ideCAD define stirrup details according to ACI 318-19?
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Stirrup legs should be extended to the compression and tension surfaces of the member as cover requirements and be anchored at both ends. To anchore anchor shear and torsional reinforcement properly, it requires a hook or bend at the end of the reinforcement.
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Straight deformed bar and wire anchorage is are forbidden. For A standard hook provides the anchorage for a No. 5 or D31 or smaller stirrup, anchorage is provided by a standard hook. According to 25.7.1.3, the anchorage of the deformed bar should be:
For No.5 bar bars and smaller , and for No.6 through No.8 bars with fyt ≤ 40 000 psi, a standart standard hook should use.
For No.6 through No.8 bars with fyt > 40 000 psi, a standard hook around a longitudinal bar plus an embedment between midheight of the member and the outside end of the hook equal to or greater than 0.014dbfyt / (λ(√f’c ). λ is given in Table 25.4.3.2.
Modification factor | Condition | Value of factor |
|---|---|---|
Lightweight λ | Lightweight concrete | 0.75 |
Normalweight concrete | 1.0 | |
| Epoxy-coated or zinc and epoxy dual-coated reinforcement | 1.2 |
Uncoated or zinc-coated (galvanized) reinforcement | 1.0 | |
Confining reinforcement ψr | For No. 11 and smaller bars with | 1.0 |
Other | 1.6 | |
Location ψo | For No. 11 and smaller diameter hooked bars:
| 1.0 |
Other | 1.25 | |
Concrete strength ψe | fc' < 6000 psi | fc' / 15000 + 0.6 |
fc' ≥ 6000 psi | 1.0 |
For a No. 6, No. 7, or No. 8 stirrup with fyt of only 40,000 psi, a standard stirrup hook around a longitudinal bar provides sufficient anchorage. For The embedment should be checked for a No. 6, No. 7, or No. 8 stirrup with higher strength, the embedment should be checked. A 135-degree or 180-degree hook is preferred, but a 90-degree hook may be used provided the free end of the 90-degree hook is extended to the full 12 bar diameters as required in 25.3.2.
The Anchorage of each leg of welded wire reinforcement forming a single U-stirrup should be
(a) Two longitudinal wires spaced at a 2 in. spacing along the member at the top of the U
(b) One longitudinal wire located not more than d/4 from the compression face and a second wire closer to the compression face and spaced not less than 2 in. from the fist first wire. The second wire is permitted to be located on the stirrup leg beyond a bend , or on a bend with an inside diameter of bend of at least 8db.
Because it is not possible to bend a No. 6, No. 7, or No. 8 stirrup tightly around a longitudinal bar, and due to the force in a bar with a design stress greater than 40,000 psi, stirrup anchorage depends on both the type of hook and whatever development length is provided. A longitudinal bar within a stirrup hook limits the width of any flexural cracks, even in a tension zone. Because such a stirrup hook cannot fail by splitting parallel to the plane o the hooked bar, the hook strength as used in 25.4.3.1(a) has been adjusted to reflect cover and confinement around the stirrup hook.
In joists, a small bar or wire can be anchored by a standard hook, not engaging longitudinal reinforcement, allowing a continuously bent bar to form a series of single-leg stirrups along the length of the joist.
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At least the greater of d/4 or 2 in. from d/2 should be arranged for the inner longitudinal wire
Stirrups are closed for torsion or integrity reinforcement. Transverse wires is perpendicular to the axis of the member. According to 25.7.1.6, stirrups are anchored
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According to 25.7.1.6.1, stirrups used for torsion or integrity reinforcement can be made up of two pieces of reinforcement: a single U-stirrup anchored according to 25.7.1.6(a) closed by a crosstie where the 90-degree hook of the crosstie.
Except for torsion or integrity reinforcement, closed stirrups can be made using pairs of U-stirrups spliced to form a closed unit which includes with lap lengths are of at least 1.3ld.
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