Addindg stories to old building

[arboi]

Hey everybody
My project is to design raising an old building of 4 stories to 5 or 6 stories and to reinforce the structure against earthquake.
The old structure is a residential concrete building with a 20x20 m' area. The walls are made of cement blocks where the floors and the columns are made of reinforced concrete.
The old building was not design to carry horizontal forces.
There are residents in the old building and they will stay along the process of building around and above them.
Since there are no planes of the old building I cannot use the old building structural elements to support the new story.
I will be satisfied to read comments regarding the structural analysis that should be done, about the differential settlements between the old and the new construction including connecting details etc.
10x

 

[paddingtongreen]

Here are some questions that might get you started.

Are you going to add a new structure to the outside of the existing building?
If you are adding a new structure outside, how much bigger?
Do you know the size of the foundations?
Are you permitted to rely on the existing structure to continue to support the existing loads?

I designed one with an exterior structure, going to the new roof level and hanging the new stories from a two way truss system. I can't tell you how well it worked because it wasn't built, the developer couldn't get financing for it.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[dik]

You should advise the owner that in adding loads to an old building, that if the building is capable of supporting the added load, there may be a change to the loading regime that may cause some differential movement... even, if construction is in close proximity.

Dik

 

[arboi]

Thanks for your comments
The idea is not to add loads to the old structure but to support the new story on columns and shear walls that will be built along the perimeter of the old structure.
The old building will continue to carry vertical loads as usual, but in case of strong EQ the new columns and shear walls will carry the horizontal forces

 

[connectegr]

While in school, working as a detailer, my first project was an Embassy Suites Hotel, built in the air space above the Palace Theater in New York City. The theater could not support any of the structural requirements of the 40 story hotel. Similar to paddingtongreen a steel structure was built around the existing structure with trusses spanning over the theater. This was a novel concept in New York, selling the airspace for new construction. The columns were fabricated from 65ksi, 6" plate. Some of which were erected and CJP spliced in 8' sections, due to the boom limitations of the cranes. And the truss joints were match drilled in the shop, due to concerns with erection fit-up.

A steel "exo-structure" may be the best option for your project. By integrating moment or braced frame exterior columns into the existing concrete, you can provide seismic reinforcement. And long span trusses can provide framing for the new floors.

http://www.FerrellEngineering.com

 

[BAretired]

Difficult to see how adding a single story above the old building could be economically justified.

I don't think you should tie into the existing structure at all. Just let the old building bump back and forth into the new columns padded with some sort of cushion to absorb some of the shock of the collisions which may be expected in a seismic event.

If you are going to spend significant time on this endeavor, better get a decent retainer up front.

BA

 

[connectegr]

Typo...

The built-up wide-flange and box columns were made with A572-42 material (42ksi)

http://www.FerrellEngineering.com

 

[dik]

Even if you don't add to it... you can still influence it...

Dik

 

[paddingtongreen]

BA,
The architect is simply allowing the building to become what it wants to be, don't pour cold water on his idea.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[BAretired]

Michael,

Sorry about that. I hadn't thought about the architect.

BA

 

[arboi]

BA
Where I come from there is not enough land and building above old building is very economic.
Here you kill few birds in one shot. The initiator gets the rights to build above the roof of the old building and in return he reinforces the structure against EQ.
By the way he renovates the old building and installs elevator.
This is a win - win situation and it is supprted by the government

 

[BAretired]

Okay, it's a good thing to do where you live. Even better would be to add two floors or maybe three.

BA

 

[arboi]

BA

The government supports only one story (tax free)
It still can be economic to build more then one story, but according to laws you must provide parking space for each apartment and this can be mission impossible