For the optimization of shear reinforcement, the beam span between columns is divided into between 3 and 5 segments depending on the length of the beam and the required shear capacity along the span. Any cantilevers at the end of a beam are divided into a maximum of 3 segments. If two adjacent segments are found to be too small to practically change the shear reinforcement, or because they have the same reinforcement spacing and size, then the segments are merged.

The start location of the first shear segment and the end location of the last shear segment in a span are located a user-specified distance from the face of the respective supporting member. This user-specified value is the End Stirrup Start Loc or Interior Stirrup Start Loc found in the Criteria > Detailing Defaults menu (see Section 3.7.2).

When an optimized design results in a span with three or more shear segments, the length of the two outer shear segments will generally be a multiple of the segment length increment specified in the Criteria > Beam Design (see Section 3.7.1). If five shear segments result from the optimization, the length of each of the outer four segments will generally be a multiple of the segment length increment. That is, the optimization does its best to make the true bar spacing in the outer segments conform exactly to the spacing callout. The balance stirrups are placed in the interior segment, with a true spacing equal to or less than the spacing callout.

If two adjacent segments share a start/end point, the more heavily reinforced segment will control, and a stirrup of that type will be placed at the common point. Thus, for a shear segment which is heavier than both of the adjacent segments on either side, the number of bars used in the zone is calculated as:

where

NB	=	Number of stirrups used in the shear segment considered
Lsgmt	=	Length of the shear segment
s	=	Spacing shown in View/Update Transverse Reinforcing page for the shear segment

Likewise, for a shear segment in which one adjacent shear segment is heavier and the other is lighter, the number of bars is calculated as:

If adjacent shear zones have identical steel area per length, the left-side segment is assumed to control.

The Bar Size Bias and Amount of Bias parameters for transverse reinforcement work in the same manner as for flexural bars. However, due to the optimization method of trying to minimize reinforcement area in conjunction with bar spacing when applicable, it is possible to end up with larger bar spacing. This occurs when providing a smaller bar spacing would unduly increase reinforcement area.