New steel beam supports beside existing p.t. bea,s 2

[ajk1]

In an exiting parking garage with post-tensioned (unbonded)tendons, it is desired to put new steel beams beside each existing p.t. concrete beam so that if all of the tendons fail the steel beams can take the load.
in a p.t. beam,
Question

Is it satisfactory to place the new steel beams on one side only of each existing conc beam? I am concerned that the existing bottom rebar in the slab will not be continuous between the new steel beams. Please see the attached sketch. Do you agree with this concern? If so, could place new steel beams each side of each existing p.t. conc beam, but this would double the on-site labour to install the beams, as well as a greater total weight of new steel.

 

[BAretired]

I do not understand. Do you mean if holes could be drilled longitudinally thru the girder? How would you drill a hole to match the curvature of a harped tendon?

Drill holes across the girders near the top so that beam tendons can pass through.

BA

 

[BAretired]

Can someone tell me how the "quote feature"on this system works? It looks neat, but I don't knows how to use it. I tried clicking on the quote icon and typing the person's name, and it displays the person's name properly, but then I do not know how to type in my response so that it appears as it does when I see responses to me.

First, highlight the text you want to quote, then press the 'quote' icon, then fill in the name of the source of the quote.

BA

 

[KootK]

I still have not figured out how to use the "quote" feature on this system! If anyone could tell me, I would be greatful.

Used in moderation, the quotation function is a great aid to communication and you definitely want it in your arsenal. I made the clip shown below for you in order to help you sort it out. If it doesn't get the job done, report back and we'll keep chipping away at it until we get it right.

 

[ajk1]

I got it now. Thanks to both of you, BARetired and KootK

 

[ajk1]

If holes could be drilled through the existing girders, the ideal solution would be to thread tendons through the girders. Then, harped grouted strands could be used which would provide negative moment resistance at girders.
BA

Yes, right, that is what I would do for the external p.t. option. Sorry I had missed that you said holes thru "girder", not thru "beam".
I think drilling thru the supporting girder as you suggest is more straightforward than trying to anchor to the end of the beam. Drilling thru girders was always my intention, though will have to be careful we don't locate the holes where the tendons are positioned in the girder. The owner will just have to live with the fact that the anchor is on the mall side of the girder. It can be covered with an appropriate architectural finish material such as drywall.

 

[BAretired]

You're welcome, but my contribution was nowhere near as fancy as KootK's.

BA

 

[ajk1]

Is anyone aware of any significant corrosion problems with grouted tendons in old (1975 or so) cast-in-place parking garages? I am not aware of corrosion problems with grouted tendons in cast-in-place garages (unlike segmental bridges where there have been problems), and have been of the understanding that they have performed well in cast-in-place parking garages, even in old parking garages.

 

[BAretired]

Quote (KootK)
I got it now. Thanks to both of you, BARetired and KootK

Wait a minute! That is what you said, not what KootK said. You have to copy the quote, paste it to your response, highlight it, then press the 'quote' icon.

BA

 

[Ingenuity]

There is I believe a company that advertises that they do urethane injection of tendons. Has anyone experience with that? My feeling is that they would not be able to prevent ongoing wire failures, but has anyone experience with it, or heard anything good or bad about it?

I am aware of the system but have not personally used it.

Jack Morrow, P.Eng, from Calgary, invented and patented a PU injection system to unbonded tendons, through his company JAMOR ENGINEERING. He has used it a bunch in the Calgary market I believe, and a company in Colorado called RESTRUCTION are a licensee and have done several projects with it too.

PTI Journal did a Case Study paper on the system (and I attach the file to this post):

Jack has been involved with unbonded PT for a long, long time, and previous past president of ICRI - real nice, and smart guy.

Dr. Randy Poston (of ICRI and ACI- 318 fame) when we has with Whitlock Dalrymple Poston & Associates did a overview of the system back in early 2000's and I have a hardcopy somewhere that states the system works, BUT should the tendons need to be removed and replaced it will be tough to do so.


EDIT: ==> Here is photo of a sample I have of the PU grouted strand:

 

[ajk1]

I am aware of the system but have not personally used it.

Jack Morrow, P.Eng, from Calgary, invented and patented a PU injection system to unbonded tendons, through his company JAMOR ENGINEERING. He has used it a bunch in the Calgary market I believe, and a company in Colorado called RESTRUCTION are a licensee and have done several projects with it too.

PTI Journal did a Case Study paper on the system (and I attach the file to this post):

Thank you Ingenuity. I will try try to look into this.