Automatic Straight Strand Pattern Generation
Precast/Prestressed Girder will automatically generate a straight strand pattern by clicking the Auto Design button on the Strand Pattern (on the Beam tab). The following algorithm is used:
- Service III limit state results are used to find the location where the maximum total final bending moment is maximum. At this location, the program calculates the minimum number of required strands that will keep the tension stress at the bottom of the beam within the allowable margins (calculated or user-modified).
- The envelope of Strength I and Strength II results is then used to find the location where the total final bending moment is maximum. At this location, the program calculates the minimum number of strands that will make the required ultimate capacity less the provided ultimate capacity (Mu-reqd < Mu-prvd).
- Then, the program adds the maximum number of strands from Step 1 and Step 2 and uses it as the required number of strands.
- The program then starts raising the top strands as far as possible while staying within the limiting stresses for the two conditions.