Bracing RC columns with Ibeams?

[2204z]

How do you brace existing RC columns? With ibeams or concrete bracing.. how is the connection done? Ty

 

[Retrograde]

Why do you need to brace existing RC columns?

 

[TLycan]

I can't answer this question at once. I need more details, such as are you going to brace it to R.C wall/column , do you wanted to lean on another system or to make a moment connection, ...etc

Regards

 

[KootK]

You could use steel or concrete members. You'd need a connection and member capable of resisting a lateral load of 2-5% Pu depending on the situation. And, of course, the bracing member would itself need to be laterally restrained via connection to a diaphragm etc. The AISC bracing provisions may be of some use 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.

 

[mes7a]

You could use steel or concrete members. You'd need a connection and member capable of resisting a lateral load of 2-5% Pu depending on the situation. And, of course, the bracing member would itself need to be laterally restrained via connection to a diaphragm etc. The AISC bracing provisions may be of some use here.

I also need to brace my frames. I'm discussing with my engineers who haven't done any. What do you mean Kootk that the laterally restrained bracing member must be connected to a diaphragm? See the image below.. the red X brace is not part of the structure but my hope to prevent rotations of the moment joints longitudinally (transverse is ok to have pure moment frames) because of the red void in bottom of front column shown in red dot (hence compromised bottom because of void filled with epoxy and foundation flexural inadequacy too). I'm wondering if it can be done that way.. or should the x brace be connected to the combined footing foundation? Does it look feasible? What are the possible connections between the pure concrete columns to bracing.. guys? Existing columns beams are all pure concrete. Thanks.

 

[2204z]

I can't answer this question at once. I need more details, such as are you going to brace it to R.C wall/column , do you wanted to lean on another system or to make a moment connection, ...etc

In seismic zones.. buildings need to be retrofitted. Most existing buildings use plain reinforced concrete. So is making them more rigid mean putting tension tie between the top and bottom neighboring columns or putting compressive struts.. and should they be stronger than the columns. Won't the connection further shear the columns. How is the connection generally done?

 

[KootK]

and should they be stronger than the columns.

I would expect that it would be desirable for the columns to be stronger than the braces. You rarely want your columns to be at the front of the line your failure hierarchy in a lateral load resisting system.

Won't the connection further shear the columns

One would probably want to detail the connection such that the shearing component of the brace forces was delivered direction to the beams.

How is the connection generally done?

This would be a difficult connection to make and, in a retrofit application, I'm not sure that there is such a thing as "typical". If I could make it work, I'd consider a gusset plate at the beam/column joint that would be attached with post installed anchors.

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.