Braced concrete frame design utilising masonry infill panels for overall stability

[patswfc]

I'm involved in a project which involves repair of a 12 storey concrete framed building.
There are a number of serious design issues with the building, one of which is the complete lack of an overall stability system!
The building has been in place for approx 10 years!

The building has solid masonry walls in several locations built between the columns throughout the height of the structure.
These could be used to act as compression struts to form a hybrid truss using the masonry walls and the RC columns to act as
vertical cantilevers to provide the overall stability. I've got hold of a few publications that discuss this approach so have
a fair idea of what is required from a design check point of view.

I have a concern about using this approach for a 12 storey tall building. Some of the guides that i have only recommend
this approach for low rise buildings, others say that it can be used for low to medium rise buildings. I cant seem to
find anything specific relating to a height limitation for a building using this method for overall stability.
Does anybody know if such a height restriction exists? I'm based in the UK.

Thanks

 

[JAE]

I find it hard to believe that a 10 year old, 12 story concrete frame building has a "complete lack of an overall stability system".

Are you sure it's not an overall moment frame building system?

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[MotorCity]

"The building has solid masonry walls in several locations built between the columns throughout the height of the structure."

......or how about shear walls for a lateral system??

 

[patswfc]

It has a "complete lack of a designed overall stability system" I kid you not.
The way that the rebar has been detailed is not that of a moment frame, plus it had been designed as such a lot of the columns would then be under-designed.
Lack of a stability system is only one of a number of serious design flaws in the structure!

There will be a bit of moment frame response due to the fact that its a concrete frame thus the beam to column joints have some stiffness, and the masonry infill panels will be acting in conjunction with the frame to form the hybrid truss that i've talked about. So there is some inherent stability in the structure.

Back to the original Q?, does anybody know of a height restriction for this stability system. I cant say I feel comfortable with 12 storeys, around 6 storeys would be the limit of my comfort zone.

 

[patswfc]

MotorCity,

The masonry walls are framed by RC beams and columns. We are looking at using these in conjunction with the RC elements to form a hybrid truss as per the attached image.