PT beam retrofiting two-way slab 1

[Intern2007]

Hi all,
I work as an intern at a Department of Building and Safety. Please advise me how to check the following failure.
The podium slab (flat slab)of an appartment fails under punching shear (span 30-33 ft). To repair, EOR proposes additional PT beams supported by new columns doweled to existing columns. The PT beams doweld to podium slab above.

Could you please give me some idea how to check the possible failure mode?
1. Will P-delta effect occur on combine (existing + new column)due to the post-tension beam?
2. How do i check the epoxy dowel (at slab/PT beam & existing/new column.)

Thanks many.

 

[lkjh345]

Intern2007:

I do not mean to offend you or anyone in your department, but this is defiantely not a problem for an intern to be looking at. From you post, I would think this is a very difficult problem, that should be carefully looked at and evaluated by a very expereinced engineer with experience in Post-Tensioned construction.

 

[Intern2007]

Thanks lkjh345 for your feedback.

Here's a more specific question: in order to have a composite member (new PT beam/existing member) how the load path work...so that i can check for the numbers of proposed dowels....how the shear will develop in this new member in regarding to long term deflection.

Thanks.

 

[hokie66]

Intern2007,

lkjh345 is right. Based on your posts, you should not be attempting to check this work without qualified guidance within your office. If you have been assigned this as an exercise only, this forum is not going to suffice as a tutorial to allow you to deal with such a difficult problem.

 

[Intern2007]

Thanks hokie66. I really appreaciate your thought.
I will graduate this summer (only 1 GE class left). I used to work as an intern for concrete design at a small firm for 2 years. Therefore, this assignment should be a very good experience for me.

The tricky part is i do not know how the new "composite" member will behave or how to justify them... basically, the load path.

I m still reading and researching more books at this topic.
Thanks all again.