Concrete moment frame supporting Shear wall

[CLARENCEQ]

Hello All,

I am designing a 9 stories + cellar project in New York. It is a concrete building. Using dual lateral system, concrete shear wall + moment frame.
There is an issue that a 17' long 12" thick shear wall has to start from 2nd floor and sit on a concrete beam which is supported by C14x30 at end. My concerns is how should I design the concrete beam and column in ETABS. I tried to directly draw wall elements on beam, the lateral performance seems good, but the gravity load cannot be correctly transferred to the beam from wall. The other option tried is to draw the wall in 12x12 column elements @12" to mimic the wall load transfer, however, the gravity load transfer looks good, the lateral performance not.
Is there any solution to design the beam and column?

Thank you so much!

 

[Agent666]

but the gravity load cannot be correctly transferred to the beam from wall

Can you explain in more detail what the issue is here to come to that conclusion?

A cross section might help to understand the configuration and geometry.

https://engineervsheep.com

 

[HTURKAK]

-It is not clear if the lateral performance is good.. If the RC wall start 2nd floor ( that is , if not planted to the foundation), the RC wall contribution to the lateral performance will be negligible..

- Eventually the RC wall will support the subject beam rather than supported on the beam. The beam would be designed for construction loading when the 2 nd storey wall conc. is fresh.

- Pls post a sketch to get more helpful responds..

 

[jayrod12]

I believe you're having the age old issue of modelling walls on beams, in that the in-plane stiffness of the wall causes it to span between columns and not load the beam. And conversely if you reduce the stiffness of the wall so it loads the beam, then the lateral stiffness of the wall becomes similar to a wet noodle.

I've often just ran the concrete moment frame by hand in those scenarios to keep the overall lateral model working properly. The reality of the situation is that the wall likely is acting like a super deep beam and the actual beam element won't end up seeing significant loads, but belt and suspenders.