Post Tensioned Slab Balcony Edge Curling 1

[Gabe_StrEng]

Hey All,
Doing an evaluation of an existing building constructed around 2006 and there is an irregular condition at one of the exterior cantilevered balconies.
1) They ran a pour strip through a portion of the balcony. Balcony is about 11' wide total and there is 6' on one side of pour strip, 3' wide pour strip, and 2' on the other side.
2) On the 6' wide side of the balcony, there's 7 PT tendons being terminated near the corner of the balcony. Obviously none in the pour strip and none in the 2' side of balcony.

This has resulted in a balcony that is noticeably jacked up on one side and there is a crack running perfectly along where the pour strip meets the 2' wide side of the balcony. (Photos attached). And it looks like they cut a control joint in the bottom of the slab up to the drip edge.

My initial evaluation is that this is a case of poor engineering judgement resulting in some bad upwards deflection, but this is really not a life safety issue and now that initial deflection and much of the long term deflection is worked out it's not going to get a whole lot worse over time. And I think actually trying to fix anything will create more issues than it solves. We're basically going to repair and seal the crack and put a sloped traffic coating to fix the drainage.
I wanted to tap into this community and see if you all agreed with my evaluation or if you would recommend anything different in this case?

Background info:
Unbonded PT slab, building is located in the Pacific Northwest

 

[KootK]

Agree on all counts. A backwards draining balcony is every PT designer's worst nightmare.

 

[Ingenuity]

Very badly thought out location of the pour strip!

The shape of the pour strip could have been reconfigured to better incorporate the balcony...but that is in the past.

Obviously none in the pour strip and none in the 2' side of balcony.

Based on the drawing you show there is one (1) tendon terminated on the RHS of the pour strip in the 2' concrete segment.

My initial evaluation is that this is a case of poor engineering judgement resulting in some bad upwards deflection, but this is really not a life safety issue and now that initial deflection and much of the long term deflection is worked out it's not going to get a whole lot worse over time. And I think actually trying to fix anything will create more issues than it solves. We're basically going to repair and seal the crack and put a sloped traffic coating to fix the drainage.
I wanted to tap into this community and see if you all agreed with my evaluation or if you would recommend anything different in this case?

I would verify (using GPR) that there is rebar transverse to the pour strip in the 2' wide balcony segment. The drawings do NOT clearly show what rebar is applicable in this area.

Otherwise, assuming no other significant defects I would proceed as you stated. I was going to suggest - rather than simply sealing the cracks - you specify epoxy pressure injection of the crack/joint - preferable from the underside of slab and 'bleed' epoxy through the top of the slab, BUT the issue will be that it will also travel horizontally along the CJ into the residence - then you have big mess. Rout-and-seal with a high-grade sealant compatible with your coating system would be better.

Good luck.

 

[Tomfh]

Yes, there seems to be a tendon in the 2' bit. And there doesn't appear to be reo across the balcony. If not, no wonder it cracked and is opening up along the pour strip.

 

[Gabe_StrEng]

Thanks for the replies!
Agreed that there's that tendon on the plan but I didn't see a grouted pocket in that 2' section so I inferred that during construction someone (smartly?) recommended not terminating a tendon in a 2' wide section of concrete. Although maybe not so smart since the adjustment didn't carry through to the layout of the pour strip. Neither here nor there at this point in time though.
Good advice on getting the GPR reading to confirm the underlying reinforcement, I'll add that to my recommendations.

Cheers
Gabe