Section 11.4 Shear Resistance of Beams (Prestressed)
See Concrete "Core" Determination.
For sections with multiple values of f ’c, the minimum f ’c is used.
The effective depth is determined by a cracked section analysis using the bending moment and axial force in place at time of the shear being investigated. The effective depth is calculated as the distance from the compression most face to the resultant tension force. For cross sections with no reinforcement in tension, a "column style" effective depth is calculated as the distance from the compression most face to the maximum depth of any reinforcement.
When the maximize effective depth option is used the effective depth is first calculated utilizing all reinforcement in the cross section. A subsequent calculation is then carried out utilizing only the reinforcement in the 1/4 depth of the cross section nearest the tension most face, and ignoring any post-tensioning. The effective depth is taken as the maximum of the two calculations. A check is carried out for the latter calculation that there is enough reinforcement to resist the tension chord of a shear truss considering only the flexural moment and shear. If this check fails the results of the latter calculation are not used.
If stirrups are provided, the effective depth of the section is considered to be the larger of 0.8×h or the calculated effective depth; otherwise the effective depth is considered to be the calculated effective depth.
Lightweight concrete is not considered.
Equation 11-9 is used to determine the shear capacity.
Equations 11-13 (including 50×bws/fy) and 11-15 are implemented.
Section 11.1.2 is implemented (but optional 11.1.2.1 is not).
Sections 11.5.2, 11.5.4.1, 11.5.4.3 and 11.5.6.9 are implemented.
A minimum reinforcement criterion of section 11.5.5 is implemented; if the member is a slab, then this requirement is waived per 11.5.5.1a.
Axial Compression (or Tension) is not considered
If "beam" torsion design is selected, see Section 11.6 Beam Torsion for further requirements.
No check is made to ensure that the structure is post-tensioned.