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[bijay sarkar]

Dear Sir,

Can some one describe the different types of major structural systems (along with the description of force flow path of each system) already used worldwide in such Tall Buildings ?


With Regards,

Bijay Sarkar

[S.KANTHIMATHINATHAN]

Dear Sirs,
Structural system
1) Braced
2) Unbraced
3) Combination of both

In my opinion, tall structures should be braced in vertical and horizontal planes. If floors are R.C.C , the same provides rigid diaphragm action.

Load path

Vertical load- floor beam to column as reaction ( with moment in case of fixed beam )
Horizontal loads ( due to wind & seismic) - through bracing members.

With kind regards,
S.Kanthimathinathan
Structural Engineering Consultant,
Tiruchy Engineering Consultancy House,
1/1-A.Nariyan Street,
Srirangam, Tiruchy-620006
( Courses offered:- Design & Detailing of steel & R.C.C Structures)



Subject: [E-CONF] Tall Building Design :: Framing System
From: forum@sefindia.org
Date: Wed, 21 Nov 2012 22:26:24 +0530
To: econf34289@sefindia.org

           Dear Sir,

Can some one describe the different types of major structural systems (along with the description of force flow path of each system) already used worldwide in such Tall Buildings ?


With Regards,

Bijay Sarkar

Posted via Email

[gautam chattopadhyay]

Is it very necessay for buildings up to 50 m to brace the external columns? If we place the shear walls judicially with sufficient srtuctural sense I think the horizontal forces will be resisted jointly by the shear walls and the columns. It must be admitted that center of stiffness and center of mass do never coincide, and columns/shear walls cannot be placed in that way. If done it will be a ridiculous design. Practicality must be addressed to. In some older buildings in Delhi and Calcutta I have seen braced columns at external peripherry. They are standing well but the buildings where such measures have not been taken are also performing well.

On Fri, Nov 23, 2012 at 11:50 AM, S.KANTHIMATHINATHAN <forum@sefindia.org (forum@sefindia.org)> wrote:

[biju]

Framing system plays a very vital role in the design of Tall buildings.
At the very beginning of a project, at the concept stage, if the Architect and Structural Eng. sit together and finalize the column/Shear wall locations, then much effectiveness in the design can be arrived at.

If it is a concrete structure, then as Mr. Chattopadhyay has mentioned, CM and CR has to coincide as far as possible. Proper load path has to be defined. Stiffness along the height has to be such that wind induced accelerations and deflections are well under control.

Stress levels in the compression members are to be proportioned, so that axial shortening effect is under check. And of course, optimum foundation system has to be arrived at, with proper stability check.

regards,

Biju






[quote="gautam chattopadhyay"]Is it very necessay for buildings up to 50 m to brace the external columns? If we place the shear walls judicially with sufficient srtuctural sense I think the horizontal forces will be resisted jointly by the shear walls and the columns. It must be admitted that center of stiffness and center of mass do never coincide, and columns/shear walls cannot be placed in that way. If done it will be a ridiculous design. Practicality must be addressed to. In some older buildings in Delhi and Calcutta I have seen braced columns at external peripherry. They are standing well but the buildings where such measures have not been taken are also performing well.

[kapildingare]

Resp. Chattopadhayji,
Your views
“If we place the shear walls judicially with sufficient srtuctural sense I think the horizontal forces will be resisted jointly by the shear walls and the columns. It must be admitted that center of stiffness and center of mass do never coincide, and columns/shear walls cannot be placed in that way. If done it will be a ridiculous design. Practicality must be addressed to.”
What I think that framing system , with shear walls , in which centre of stiffness and centre of mass does not coincide, presence of shear walls itself is creating more problems than giving solutions.
I would like your expert opinion in selecting frame system,
1)     Framing system in which shear walls placed with eccentricities with respect to center of mass.
2)     Framing system in which columns are diagonally braced and such frame is resisting lateral loads.

Would like your attention on photos of
1)     Bhuj Earthquake : RCC Building failure with lift/stair case with rcc walls standing erect.
2)     Cover photo on mag. Earthquake Engineering Practices—Sept 2012 (NICEE)


Thank you,

                                                               Kapil Dingare

[gautam chattopadhyay]

You are true, in fact very true to say eccentric shear walls pose bigger problem in distribution of storey forces. I told you we cannot place our shear walls at our wills since then the internal arrangement of columns will become very ridiculous from architectural point of view. We have to compromise somewhere. Your proposal of braced column is nothing but an open web shear wall but again, architecturally will it look good? we have to think pragmatically and have to serve all the purposes - service, beauty, comfort of end users - all. What I feel, in normal course of working never the center of stiffness and center of mass will coincide. Ok, how much will be the storey torsion? by how much will your storey shear increase? How much will be additional shear and moment on the columns and shear walls? can we not provide some additional reinforcements for the same?

On Mon, Nov 26, 2012 at 6:26 PM, kapildingare <forum@sefindia.org (forum@sefindia.org)> wrote:

[baldevprajapati]

hallo sir r  u know the  design of tall building by Etabs ?

[baldevprajapati]

i have a problem to design 30 story building By etabs & ISMB600 section  is limit in the code , these section is fail so i how to sole the these probleme
thank u sir

[thirumalaichettiar]

[thirumalaichettiar]