Question about beam-column connection detail.

[kunfukenny]

Hello,

I am a structural engineer working in Korea.

I have some questions that came up while designing an underground parking lot, so I am writing this thread

The structure is a two-story underground parking lot with a rigid frame. The cross-section of the girders on the roof of the underground parking lot is 800x800, and the cross-section of the columns is 500x800. The girders are 300 wider than the columns. My questions are as follows:

1) How should the rebar be anchored when the outermost girder extends beyond the width of the column in the outermost columns and girders? Is it acceptable to anchor the rebar coming from the girder in another direction connected to the column?

2) The column dimensions are 500x800. The ldh for rebar UHD22 600MPa seems to be about 410mm with a concrete strength of 30MPa. Is it correct to set it to 500 by adding the cover? It seems that the beam girder and column dimensions are almost standardized. Am I correct in my understanding? When designing, do you roughly calculate the axial force to determine the cross-section of the columns and then adjust the details accordingly?

3) If the column dimensions cannot accommodate the required anchorage length, is there a solution? If it is possible to anchor the wide girder rebar to another girder, would it be acceptable to anchor the girder in one direction sufficiently to the column and then anchor the perpendicular girder to the existing girder? (The existing column is set to 400x800, and increasing it to 500 would destroy the parking space.)

I have been pondering these questions for a while, and I decided to ask for your help since I couldn't find clear answers through online searches and didn't have anyone to consult within my company.

I hope you are doing well during this hot summer.

Best regards,

 

[BIM there done that]

Hello!

I would say your primary concern with the wide beam-column joint should be the shear transfer as well as the torsion of the beams you are anchoring your girders into. A good starting point would be to consult ACI 352R-02. There is another useful post that you may take a look at.

https://www.eng-tips.com/viewthread.cfm?qid=417050

The anchorage itself can be solved in multiple ways if there is not enough space. You can use a headed rebar for example. However, you need to consider the load paths; where are the forces going past the anchorage point.

Finally, it would be useful to share some additional information for better understanding of the problem. Slab thickness, spans. A hand sketch of a plan, section, etc.