[SEFI] Suggetion regarding floating columns

[tajusk2000]

Dear all,

I have to design a building with 36 floating columns which rest on 16 main coluns. can u suggest any code reg floating columns. Is there any restriction on no of floating columns?. Is floating column advisable?
By providing floting columns what are disadvantages? The building has to design for 10 floors. floating columns will start from first floor.


plz help me reg this matter.

Thanking u,
Taj.


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[sdec.in]

It does appear to be a rather odd configuration for any structure to have so many floating columns.What structure ? What are you designing and in which seismic Zone? Is it for Architectural or for functional reasons, that it's not possible to start these columns from Ground Floor?
This will create a serious structural irregularity, and will need to be analysed with caution; its something I would personally like to avoid.
Regards
Sangeeta Wij

Quote:

http://www.sefindia.org/forum/viewtopic.php?p=8207#8207

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[keyamitra]

The poor performance of buildings with floating columns was amply demonstrated in the Bhuj 2001 earthquake. An excellent discussion on the problems of this typology is there in the Special Supplement A to Earthquake Spectra Volume 18, also available in a set of 2 CD's on the Bhuj Earthquake from NICEE, IITK. In case you are in a hurry, let me know and I can send you (as an email attachment) the chapter on RC frame buildings where the floating column problem is addressed Do please go through it and try and avoid.

Regards,

Keya Mitra

On Thu, Aug 28, 2008 at 2:50 PM, fo...@sefindia.org (fo...@sefindia.org)> wrote:
[quote] It does appear to be a rather odd configuration for any structure to have so many floating columns.What structure ? What are you designing and in which seismic Zone? Is it for Architectural or for functional reasons, that it's not possible to start these columns from Ground Floor?

This will create a serious structural irregularity, and will need to be analysed with caution; its something I would personally like to avoid.
Regards
Sangeeta Wij

[b]--auto removed--

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[akbar.civil]

Dear Mr. Taj,

36 floating columns on 16 main columns ...... hmmm ....odd configuration indeed.

I personally believe that the biggest problem with such large amount of floating columns will be the formation of a soft story which becomes an easy prey for earthquakes. It would be worthwhile to remember that the ground floor of most of the residential buildings is already a soft story and innumerable photos are available on internet showing collapse of the columns in ground floor under earthquakes. That too its happening without the benefit of floating columns.

However as a Structural Engineer I believe that nothing is impossible. But this being a very sensitive area, I believe we should wait until the code comes out with very proper guidelines which will ensure acceptable performance of floating columns under all conditions.

Regards,
Akbar

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[drnsmani]

Hi Mr. Akbar,

You wrote: "we should wait until the code comes out with very proper guidelines which will ensure acceptable performance of floating columns under all conditions". I am afraid you have to wait indefinitely, as no code will accept floating column or concealed beam!

Best wishes
Subramanian

Dr.N.Subramanian,Ph.D.,F.ASCE, M.ACI,

Computer Design Consultants: www.cdcstruct.com
Maryland, USA

See my books at: www.multi-science.co.uk/subramanian-book.htm
www.oup.co.in/search_detail.php?id=144559





--- On Thu, 8/28/08, akbar.civil wrote:

Quote:

From: akbar.civil Subject: [SEFI] Re: Suggetion regarding floating columns To: gen...@sefindia.org Date: Thursday, August 28, 2008, 8:19 PM

Dear Mr. Taj, 36 floating columns on 16 main columns ...... hmmm ....odd configuration indeed. I personally believe that the biggest problem with such large amount of floating columns will be the formation of a soft story which becomes an easy prey for earthquakes. It would be worthwhile to remember that the ground floor of most of the residential buildings is already a soft story and innumerable photos are available on internet showing collapse of the columns in ground floor under earthquakes. That too its happening without the benefit of floating columns. However as a Structural Engineer I believe that nothing is impossible. But this being a very sensitive area, I believe we should wait until the code comes out with very proper guidelines which will ensure acceptable performance of floating columns under all conditions. Regards, Akbar

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[thensenamar mp]

DEAR TAJ
ITS HIGH TIME TO EDUCATE THE ARCHITECT'S & BUILDERS ABOUT THE DISADVANTAGES OF FLOATING COLUMNS. BEST EXAMPLE IS BHUJ EARTHQUAKE. IF PEOPLE DOES NOT LEARN FROM EARLIER MISTAKES ITS
DISGRACE TO THE SOCIETY.
WILL ANY ONE STAND UP AND TAKE THIS ISSUE TO THE ARCHITECT'S ASSOCIATION.
JUST FOR THE SAKE OF MONEY U CANNOT AFFORD THE LOSE OF HUMAN BEING LIVES.

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[prof.arc]

I would think that the word COLUMN should be used only for a vertical member which emanates from a foundation. A vertical member which terminates at a higher level only puts a concentrated load (near the middle of the beam depending on its location) and the main beam can be designed without having recourse to this useless vertical member called floating structure.
Secondary beams are used with main beams to carry floor loads to reduce thickness of floor slab.
May be if you have a problem with thickness of shear wall, you can provide vertical stiffeners but please DO NOT MISUSE the name "column" .
Instead of floating we only drown.
Sorry for commenting strongly but Kutch earthquake lessons should not be forgotten so early.

ARC


On Thu, Aug 28, 2008 at 12:21 PM, tajusk2000 fo...@sefindia.org)> wrote:

Quote:

Dear all, I have to design a building with 36 floating columns which rest on 16 main coluns. can u suggest any code reg floating columns. Is there any restriction on no of floating columns?. Is floating column advisable? By providing floting columns what are disadvantages? The building has to design for 10 floors. floating columns will start from first floor. plz help me reg this matter. Thanking u, Taj.

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[sdec.in]

very well said indeed! we must refrain from getting into a structural mess on account of certain individual fancies.
Sangeeta Wij
[quote] ----- Original Message -----
From: prof.arc (fo...@sefindia.org)
To: gen...@sefindia.org (gen...@sefindia.org)
Sent: Friday, August 29, 2008 8:00 AM

Subject: [SEFI] Re: Suggetion regarding floating columns

I would think that the word COLUMN should be used only for a vertical member which emanates from a foundation. A vertical member which terminates at a higher level only puts a concentrated load (near the middle of the beam depending on its location) and the main beam can be designed without having recourse to this useless vertical member called floating structure.
Secondary beams are used with main beams to carry floor loads to reduce thickness of floor slab.
May be if you have a problem with thickness of shear wall, you can provide vertical stiffeners but please DO NOT MISUSE the name "column" .
Instead of floating we only drown.
Sorry for commenting strongly but Kutch earthquake lessons should not be forgotten so early.

ARC


On Thu, Aug 28, 2008 at 12:21 PM, tajusk2000 fo...@sefindia.org)> wrote:

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