Post Tension Slab on Grade Prestress Values
Post Tension Slab on Grade Prestress Values
(OP)
I am currently working on the design of a PT slab on grade for a small PEMB structure that is 60'-0" x 100'-0". I'm using the program PTISlab3.5 to run the analysis. Under the Prestress value for the slab tendons, I have always used 50 psi, however I have heard that 75 psi is becoming more common. Does anyone know more information about this and how much of a difference this really makes??






RE: Post Tension Slab on Grade Prestress Values
RE: Post Tension Slab on Grade Prestress Values
RE: Post Tension Slab on Grade Prestress Values
Agree with your numbers. They will have nothing after shortening restraint losses etc. Probably why there are so many complaints about cracking in residential PT slabs in USA! And with unbonded PT, there will be no crack control either!
RE: Post Tension Slab on Grade Prestress Values
RE: Post Tension Slab on Grade Prestress Values
And then, from what I have been told, putting pressure on others in the industry to hide the problems!
RE: Post Tension Slab on Grade Prestress Values
Is it primarily a flat slab type system in the southern hemisphere, or do you also do the ribbed ones? To me the ribbed ones are the only ones that can really be stiff enough to work.
RE: Post Tension Slab on Grade Prestress Values
dcarr82775: in the Southern Hemisphere, residential foundations are very, very seldom constructed with PT. In Australia specifically, where UNbonded PT is not permitted for suspended framing systems, SOG PT is usually only used on large warehouse and intermodal slabs, uniform slab thickness, and bonded PT.
RE: Post Tension Slab on Grade Prestress Values
What Ingenuity said, as to PT slabs. We do use a lot of ribbed slabs in residential work, with conventional reinforcing, and they work.