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TO: Bridge Designers
FROM: Chuck Ruth
DATE: July 19, 1994
SUBJECT: Prestressed Girder Straight Strand Patterns

The current WSDOT prestressed girder standards for girder types W50G, W58G, W74G, W35DG, and W53DG limit the total number of straight prestressing strands in the lower flange to 26. In order to accommodate the special situation where 28 straight strands may be required, designers may now use the strand geometry shown on the attached sketch. We are not changing the current standard; the attached sketch is valid only for the particular case where 28 strands are required. The standard girder details sheet must be modified accordingly when the 28 strand pattern is used. Please note the three basic differences:

  1. Strands are not aligned vertically within the lower flange
  2. Vertical spacing between horizontal strand layers is 1-3/4"
  3. The distance from bottom of the lower flange to the centroid of the lower strand
    layer is 1-3/4" rather than the 1-7/8" shown in the standard girder details in order
    to accommodate minimum clear cover of 1-1/2" at the upper surface of the lower flange.

If you have any questions regarding this memorandum, contact Ralph Dornsife at (206)-705-7199.