|Fns = fceAcs||(23.4.1a)|
|Fns = fceAcs+ A'sf's||(23.4.1b)|
where Fns shall be evaluated at each end of the strut and taken as the lesser value; Acs is the cross-sectional area at the end of the strut under consideration; fce is given in 23.4.3; A's is the area of compression reinforcement along the length of the strut; and f's is the stress in the compression reinforcement at the nominal axial strength of the strut. It shall be permitted to take f's equal to fy for Grade 40 or 60 reinforcement.
|fce = 0.85βs fc'||(23.4.3)|
|Strut geometry and location||Reinforcement crossing a strut||βs|
|Struts with uniform crosssectional area along length||NA||1.0||(a)|
|Struts located in a region of a member where the width of the compressed concrete at midlength of the strut can spread laterally (bottle-shaped struts)||Satisfying 23.5||0.75||(b)|
|Not Satisfying 23.5||0.60λ||(c)|
|Struts located in tension members or the tension zones of members||NA||0.40||(d)|
|All other cases||NA||0.60λ||(e)|
|Fnt = Ats fy+ Atp(fse+ Δfp)||(23.7.2)|
where (fse + Δfp) shall not exceed fpy, and Atp is zero for nonprestressed members.
|fce = 0.85βn fc'||(23.9.2)|
where βn shall be in accordance with Table 23.9.2.
|Configuration of nodal zone||βn|
|Nodal zone bounded by struts, bearing areas, or both||1.0||(a)|
|Nodal zone anchoring one tie||0.80||(b)|
|Nodal zone anchoring two or more ties||0.60||(c)|