Precast/Prestressed Girder Help

Automatic Draped Strand Pattern Generation

Precast/Prestressed Girder will automatically generate a draped strand pattern by clicking the Auto Design button on the Strand Pattern . The following algorithm is used:

  1. A straight pattern is generated following the algorithm described above, except without the last step of raising the top strands.
  2. The topmost group of strands in the web is raised at the end of the beam, one row at a time. When it reaches the top, the same procedure is done with the next topmost group of strands. This process is repeated until the following service stresses are all within the allowable for all locations along the beam that are affected by draping:
    • Tension at precast top at release.
    • Compression at bottom at release.
    • Tension at precast top at final, due to negative moment envelope.
    • Compression at bottom at final, due to negative moment envelope.
  3. This process of incrementing draping is stopped whenever any of the following exceeds the allowable at any of the locations along the beam that are affected by draping:
    • Tension at bottom at final, due to positive moment envelope.
    • Ultimate capacity, due to positive moment envelop.e
Parent topic: AASHTO LRFD