American Concrete Design
Section 3
3-34
If both Mx1 and My1 are positive, Mxd = 0 and Myd = 0.
If both Mx1 and My1 are negative, Mxd = Mx1 and Myd = My1.
If Mx1 is negative and My1 positive, Mxd = Mx2 and Myd =
0.
If My1 is negative and Mx1 positive, Mxd = 0 and Myd =
My2.
Mxd and Myd are then used in lieu of Mx and My for calculations
of the required reinforcing.
Punching shear design notes:
• Design for two-way shear is carried out in accordance with
Section 11.12.
• The unbalanced moment transfer by eccentricity of shear is
based on Clause 11.12.6.
• Shear strength of concrete is based on Clause 11.12.2.1.
• Strength reduction factor used is 0.75, in accordance with
Section 9.3.2.
The program computes shear stress values at four corners of the
rectangular critical section located at the distance of d/2 from
edges of a column. The calculations include the unbalanced
moment transfer effect, if applicable, in accordance with 11.12.6.2.
These values are compared with the design strength stress and a
Pass or Fail identifier is reported.
