Pinned detailing between beam and column in rc construction.

[chekre]

Hello i have been searching posts  in this forum about achieving a pinned connection in a beam column rc building.
Lets consider that i have a beam resting on a column at a roof level (or intermediate one).
 I would like to design this beam in order not to transmit moments to the columns
Pinned concrete detailing cant be really achieved where the elements are built integrally (unless precast element or corbel / bracket element). So thinking loudly i think the best way is to put some minimal top reinforcement in the discontinious part and design the beam as pinned at its end.
Note that the column will be designed with a phi*Mn generated by the minimal top reinforcement located at the column location.
Also note that this is a particular case where the column on which the beam is resting has 20 cm width and it cant be increased.
Generally i am not a fan of releasing moment in rc construction.
Is there any method of reinforcement detailing  achieving the above? Thank you.
 

 

[KootK]

I've got a decent collection of articles on this topic: Link. I'm not sure that any of them will quite fit what you want to do however (most pertain to bridge piers). There are some good detailing suggestions though.

In my mind, the strategy that you've proposed is less "creating a pin" and more "capacity designing the column for the beam negative flexural capacity". As such, I would:

1) Look into and apply provisions similar to the high seismic concrete moment frame provisions.

2) Design the column for the force demands arising from the development of the over-strength flexural capacity of the beam (phi = 1.25).

My suspicion here is that you're attempting to make do with a column size that cannot accommodate the moments coming in from the attached beam. Attempting to do that by detailing the moments away is a dangerous game in monolithic construction. That is one important reason why I favor a capacity design approach here.




I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[chekre]

Thank you kootk for your answer.
Couple of things to add:
1- I am restrained by the column of 20 cm (arquitectural reasons). The zone is non seismic
2- I will use the 1.25fy and if the column can not accomodate the moment generated by the top steel of the beam i will enlarge it from the other direction.
3- I will use small bars diameters so it can be developed in a 20cm column.
4- The beam reinforcement will be designed taking into account a pinned end.
5- As for the column it will absorb the moment transmitted from tbe top beam steel. So if it can accomodate this moment i think that the structure is safe.
I will check the link once i arrive tomorrow to the site. Thank u for the info.