precast prestressed columns 1

[WillPESE]

I am looking for a modern software for the design of precast prestressed columns that can automatically conduct structural analysis and design based on ACI 318. I need it for a large parking structure.

 

[KootK]

I believe that both of these will do what you seek:

1) LECWall

2) Eriksson Wall

Out of curiosity, what are you hoping to accomplish by prestressing the columns? In my experience, prestressing columns doesn't tend to yield a whole lot of benefit other that simply replacing rebar if that's your fabricator's preference. I've found it rare that precast columns are slender enough to see the benefit.

 

[DRWR]

I am using PPC Column Software from Precast Computing. Here is the software page:

[URL unfurl="true"]https://www.precastcomputing.com/ppc-column/[/url]

It can handle non-prestressed and/or prestressed precast columns with rectangular sections. I hope this is what you are looking for.

KootK,
I am dealing with some precasters that prefer to use precast column for faster column cage construction.

 

[Gaurav Malya]

KootK ,you can waive off creep shrinkage requirements if you prestress the column with an average effective prestress greater than 225 psi.

 

[rapt]

I am with you on you final comments on this one Kootk.

Pretensioning is used in driven piles due to the tension in the pile from the driving.

I see no logic for its use in columns.
- Ultimate axial capacity is reduced
- there is a zone at the end with 0 reinforcement and therefore technically 0 axial and bending capacity and then gradually increasing capacity over the Transmission Length.
- it would be interesting to see how connection details can be justified
- there is no saving of "shrinkage and creep" requirements as you have simply replaced the minimum steel with prestressing steel, not that I would have thought that would affect columns anyway. Minimum column reinforcement requirements should still control.

 

[Gaurav Malya]

@rapt.... I agree with your point of zero axial and bending capacity at the end zone.
But you can structurally configure your system such that the first point of load application is at some distance below the end of the member and give a restraint (pin restrain) above the load location. So technically you won't have any demand in the end zone.
And regarding creep and shrinkage requirements, for a 24" x 24" doesn't it sound a huge difference when you compare 4nos. of 9/16" strands each stressed to 38.9kip with 4nos. of #11 bars!!

 

[rapt]

Gaurav Malya
Yes, you can allow for it if you understand.

Most pretensioned spanning member designs I see show no understanding of the need to have tension capacity at the end of the member and the fact that pretensioned strands provide zero.