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# 22.4 Axial Strength or Combined Flexural and Axial Strength

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22.4.1 General
22.4.1.1
Nominal flexural and axial strength shall be calculated in accordance with the assumptions of 22.2.
22.4.2 Maximum Axial Compressive Strength
22.4.2.1
Nominal axial compressive strength Pn shall not exceed Pn,max in accordance with Table 22.4.2.1, where Po is calculated by Eq. (22.4.2.2) for nonprestressed members and by Eq. (22.4.2.3) for prestressed members. The value of fy shall be limited to a maximum of 80,000 psi.
Table 22.4.2.1—Maximum axial strength
Member Transverse reinforcement Pn,max
Nonprestressed Ties conforming to 22.4.2.4 0.80Po (a)
Spirals conforming to 22.4.2.5 0.85Po (b)
Prestressed Ties 0.80Po (c)
Spirals 0.85Po (d)
Deep foundation member Ties conforming to Ch. 13 0.80Po (e)
22.4.2.2
For nonprestressed members, Po shall be calculated by:
 Po = 0.85fc'(Ag — Ast) + fyAst (22.4.2.2)
where Ast is the total area of nonprestressed longitudinal reinforcement.
22.4.2.3
For prestressed members, Po shall be calculated by:
 Po = 0.85fc'(Ag — Ast — Apd) + fyAst — (fse — 0.003Ep)Apt (22.4.2.3)
where Apt is the total area of prestressing reinforcement, and Apd is the total area occupied by duct, sheathing, and prestressing reinforcement; the value of fse shall be at least 0.003Ep. For grouted, post-tensioned tendons, it shall be permitted to assume Apd equals Apt.
22.4.2.4
Tie reinforcement for lateral support of longitudinal reinforcement in compression members shall satisfy 10.7.6.2 and 25.7.2.
22.4.2.5
Spiral reinforcement for lateral support of longitudinal reinforcement in compression members shall satisfy 10.7.6.3 and 25.7.3.
22.4.3 Maximum Axial Tensile Strength
22.4.3.1
Nominal axial tensile strength of a nonprestressed, composite, or prestressed member, Pnt, shall not be taken greater than Pnt,max, calculated by:
 Pnt,max = fyAst + (fse + Δfp)Apt (22.4.3.1)
where (fse + Δfp) shall not exceed fpy, and Apt is zero for nonprestressed members.

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