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Re: Post Tensioning (SAP Question)

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Wael Shabana wrote:

<I am designing a structure whose system includes Walls which act as part =
of the gravity system and shear wall as well. The walls act like =
cantilever (cantilever span is 43' , worst span). I modeled the walls as =
shells on the SAP 2000 however I want to locate PT cables in those =
cantilevered parts of the wall. My question, is there a way to introduce =
the PT forces to the shells in the SAP or it is only available for =
Frames. If so, how do I model this wall as a frame? The wall height is =
55' and rests on a fdn mat on a length of only 42'. The walls total =
length is 104'>

Although not an answer on how to use SAP for this, you might want to try
accounting for the PT forces by using equivalent loads.  The references that I
have for this are the "Post Tensioned Box Girder Bridge Manual" by the Post
Tensioning Institute ;"Simplified Equivalent Loads of Prestressing", ASCE
Journal of Structural Engineering, November, 1991; PCI Journal, February, 1966;
and "Design of Prestressed Concrete Structures" by T. Y. Lin and Ned Burns.

An equivalent load is usually a series of uniform loads that induce in the
structure the same stresses that the PT tendons do.  I have used these loads to
help analyse PT bridges, but they should also work for your situation.

--Kipp A. Martin, S. E.
  Portland, Oregon