Beam Shear Reinforcement in RAM Concept

Question

I'm using RAM concept to analyze a pan joist system being supported by mild & post-tensioned beams. When looking at the shear reinforcement, the program is providing many more stirrups than expected. The shear demand (Figure 1) shows that the capacity (Figure 2) is not exceeded but, the shear reinforcement suggests otherwise (Figure 3). I'm unclear on why this is occurring any guidance would be helpful.

Also, at the second joist from the top, the program is changing the stirrup spacing, this creates a spike in the capacity at this location, I am unclear why it would need to change spacing at this location as the applied shear does not warrant this.

Some additional information on the beam in the figures below , the 48Wx21DP exterior beam running north-south in the figures below is a mild beam being supported in the south by a column above & below and being supported in the north by a cantilevered beam.

Figure 1: Maximum/Minimum Shear Demand

Figure 2: Maximum/Minimum Shear Capacity

Figure 3: Shear Reinforcement

Karl G · Accepted Answer

You want to select "Code" for the CS Min Shear Reinforcement Requirement option. When "Shear" is selected, the program details open, stirrups that meet the ACI's minimum requirements even when those stirrups are not required by code. See excerpt below from the RAM Concept Manual for more information on each option.

Seth Guthrie · Answer

You'll find some useful tips on one way shear design here: 
 
 RAM Concept Shear Reinforcement FAQ 
 
 We do not specifically design pan joists, so the strips are treated as beams. 
 Proper design strip definition is critical. See: 
 
 RAM Concept Design Strips TN 
 
 Net tension and torsion are the two other common factors leading to high levels of shear reinforcing.

Beam Shear Reinforcement in RAM Concept

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