Define a post-tensioning duct

Item	Description
Outside Diameter (OD)	Enter the outside diameter of the duct
Inside Diameter (ID)	Enter the inside diameter of the duct
Nominal Diameter (ND)	Enter the nominal diameter of the duct
Strand Offset (Z)	Enter the strand offset. See LRFD C5.9.1.6

‍Note: Starting with the AASHTO LRFD Bridge Design Specifications, 9th Edition, 2020, the duct diameter for LRFD 5.4.6.2 and 5.7.3.3 is based on "Shear Behavior of Spliced Post-Tensioned Girders", Moore. A. et al. These provious were developed based on the nominal diameter of the duct. The outside duct diameter is used for AASHTO LRFD specifications before the 9th Edition.