www.sefindia.org

[Econf_Moderator]

Dear All:

Fourth day into the Econference we thought we will talk about a few issues:

a) We are aware that there is a delay in receiving mail of Econference
in your mailbox- That is because Google is having some problems with
the speed and volume at which emails are being generated and blocks us
often. We are working on this with them. Those with google ids will
especially be experiencing this. Our suggestion is- Pl go  to the
website and check discussions there  until the matter is fixed.

b) Resource Persons- At this point we would like to acknowledge the
presence of our resource persons- Dr Suresh Kumar (RWDI) for wind
engineering issues, Dr N Subramanian whom you all know well, Mr
Jaydeep Wagh for geotech issues (alongwith moderators). We are
expecting many more resource persons to participate - an Econference
is an ideal way of sharing your experiences and knowledge- this only
enhances your stature and knowledge base too; so I once again request
all of you to participate. At  this point we would also like to
acknowledge Mr T Rangarajan's (our conference raconteur -we prefer
that word to rapporteur) hard work in summarising daily discussions.
You may go to his summing up mail each day for a quick update of the
previous day's  deliberations.

c) Discussions- Someone mentioned there should be a lot more
discussions on Tall Buildings  than we are seeing. We agree. The
logistics challenges mentioned in a) above notwithstanding, we need
more of you to join the debate. Already we are seeing a surge in
issues raised in the past 30 hrs. We now have  many people asking many
interesting questions and some v informed discussions, but we also
have to have more  of us attempting to address the queries. Else the
econference will end up with a lot of questions being raised, but few
answered.

Happy Econferencing!


CVR Murty, IIT Madras
Swaminathan Krishnan, Caltech (Ca, USA)
Alpa Sheth,  VMS Consutlants Pvt. Ltd., Mumbai

Posted via Email

[thirumalaichettiar]

The quote from Dr.CVR.Murthy from his posting is:

We now have  many people asking many interesting questions and some v informed discussions, but we also have to have more  of us attempting to address the queries. Else the e-conference will end up with a lot of questions being raised, but few answered.

I endorse his view and need an immediate response is urgently needed else it will be huge amount.

T.RangaRajan.

[Dr. N. Subramanian]

Dear Er Rangarajan,

I also want  more number of persons answering the questions. Somehow, we are missing the contributions of Er. Vikramjeet. Hope he is OK and will join in the discussions soon.

Regards,
Subramanian

[Shekhar]

When we design buildings in seismic areas what if we design the building by making some structural members weaker to dissipate earthquake energy thus protecting more crucial members - in effect these weaker members act like a "structural fuse" just like how an electrical fuse works in an electrical circuit. These damaged 'structural fuses" then can be repaired ( we replace "electrical fuse" in a circuit when it blows off and protects other major appliances from getting damaged) and thus we can save the more crucial members from damage and thus the building can be saved from collapse.

-Shekhar Panandiker


Please reply on our new id:
shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com) OR
info@shekharpanandiker.com (info@shekharpanandiker.com)

SHEKHAR PANANDIKER & ASSOCIATES,
Consulting Structural Engineers & Architects,
Wing A, second Floor, Hiraniketan,
Margao - Goa 403601

Tel: +91-832-2738399, 2705947
Fax: +91-832-2705947

Visit us at: www.shekharpanandiker.com

[S.KANTHIMATHINATHAN]

instead , we can use springs and hinges for the base.

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] Re: Emailing challenges, Resource persons, Discussions
From: forum@sefindia.org
Date: Fri, 23 Nov 2012 10:02:09 +0530
To: econf34289@sefindia.org

           When we design buildings in seismic areas what if we design the building by making some structural members weaker to dissipate earthquake energy thus protecting more crucial members - in effect these weaker members act like a "structural fuse" just like how an electrical fuse works in an electrical circuit. These damaged 'structural fuses" then can be repaired ( we replace "electrical fuse" in a circuit when it blows off and protects other major appliances from getting damaged) and thus we can save the more crucial members from damage and thus the building can be saved from collapse.

-Shekhar Panandiker


Please reply on our new id:
shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com) (shekhar@shekharpanandiker.com (shekhar@shekharpanandiker.com)) OR
info@shekharpanandiker.com (info@shekharpanandiker.com) (info@shekharpanandiker.com (info@shekharpanandiker.com))

SHEKHAR PANANDIKER & ASSOCIATES,
Consulting Structural Engineers & Architects,
Wing A, second Floor, Hiraniketan,
Margao - Goa 403601

Tel: +91-832-2738399, 2705947
Fax: +91-832-2705947

Visit us at: www.shekharpanandiker.com
      --auto removed--

Posted via Email

[knsheth123]

Dear SEFINs,


I have some important issues regarding the analysis and design of Tall Structures mainly related to foundation.


1.   For Modeling of Superstructure for Vertical Loads, Seismic and Wind Load Analysis,  how far it is justified to assume Fixed Base for a Raft Foundation for which allowable settlement is 100mm and differential settlement of the order of half the total settlement.  
The base condition should have significant effect on natural frequency of Tall Building. Especially for Dynamic Wind Analysis and Drift Calculations.
 
2.  The Super Structure is modeled as 3-D Space frame with line(Discrete) elements only. For the lower Storey Columns, the size effect will be significant probably to increase the stiffness from line element models. How the size effect is accounted for while carrying out performance analysis using non linear models.  
 
3. The Piled Raft is a great solution for Foundation of Tall Building. But it requires expertise and vast experience in both Structural Engg. + Geotech Engg. Like Prof. Poulos. In South Korean Piled Raft - the Raft is 5m thick and very closely spaced Piles of 2.50m diameter are used. The design of Raft from Solid (3-D) Finite Elements is not a conventional design process.  Also Structural design requires effective length of Piles having long unsupported length thro’ reclaimed soil.  
     Kindly throw some light on how we handle foundations for Tall Building in India.  
From Investigations, Interpretation, Analysis and Design View Point.
      Would like to learn more on the Interaction Analysis, if carried out in India.  
 
4.  Requirements to protect Non-Structural Elements from collapse/outside fall during EQ. Requirements for Services (HVAC, MEP etc.) to prevent hazards during EQ.
   
5.  How to identify need for Construction Stage Analysis


It is great to have such a great opportunity to learn seating at Home.
Thanks to SEFI

 
K. N. Sheth 
Dharmsinh Desai University
Nadiad.

Posted via Email

[Dr. N. Subramanian]

Dear Prof. Sheth,

Thank you for sharing your useful thoughts. The recent NEHRP Seismic Design Technical Brief No. 7 on Seismic Design of Reinforced Concrete Mat Foundations: A Guide for Practicing Engineers, may help. I sent the link a couple of days ago. I am sending it again for your easy reference, from where all the 7 Technical Briefs for practicing engineers can be downloaded. However it does not talk about piled raft.
http://www.nehrp.gov/library/techbriefs.htm

Soil-structure interaction is covered only briefly in this Technical Brief. Please refer to NIST GCR 12-917-21 “Soil-Structure Interaction of Building Structures” (NIST 2012).

Warm regards,
Subramanian

[sarfaraj.husain]

nice posting by Mr. Sheth

some points to add..


1.piling is an costly affair....puts extra cost on project...
2.piling in low sbc area with zone of liquifaction requires expertise in design for calculating length of pile...
3.difficult to model superstructure with piled raft...
4.difficult to transform lateral effect of pile in software get actual behaviour of structure...
5.very few literature is available about pile designing....


expert may provide their opinion..


sarfraj





From: "Dr. N. Subramanian" <forum@sefindia.org>
To: econf34289@sefindia.org,  
Date: 11/24/12 08:34 AM
Subject: [E-CONF] Re: Emailing challenges, Resource persons, Discussions



Dear Prof. Sheth,

Thank you for sharing your useful thoughts. The recent NEHRP Seismic Design Technical Brief No. 7 on Seismic Design of Reinforced Concrete Mat Foundations: A Guide for Practicing Engineers, may help. I sent the link a couple of days ago. I am sending it again for your easy reference, from where all the 7 Technical Briefs for practicing engineers can be downloaded. However it does not talk about piled raft.
http://www.nehrp.gov/library/techbriefs.htm

Soil-structure interaction is covered only briefly in this Technical Brief. Please refer to NIST GCR 12-917-21 “Soil-Structure Interaction of Building Structures� (NIST 2012).

Warm regards,
Subramanian

knsheth123 wrote:  Dear SEFINs,


I have some important issues regarding the analysis and design of Tall Structures mainly related to foundation.


1. For Modeling of Superstructure for Vertical Loads, Seismic and Wind Load Analysis, how far it is justified to assume Fixed Base for a Raft Foundation for which allowable settlement is 100mm and differential settlement of the order of half the total settlement.
The base condition should have significant effect on natural frequency of Tall Building. Especially for Dynamic Wind Analysis and Drift Calculations.

2. The Super Structure is modeled as 3-D Space frame with line(Discrete) elements only. For the lower Storey Columns, the size effect will be significant probably to increase the stiffness from line element models. How the size effect is accounted for while carrying out performance analysis using non linear models.

3. The Piled Raft is a great solution for Foundation of Tall Building. But it requires expertise and vast experience in both Structural Engg. + Geotech Engg. Like Prof. Poulos. In South Korean Piled Raft - the Raft is 5m thick and very closely spaced Piles of 2.50m diameter are used. The design of Raft from Solid (3-D) Finite Elements is not a conventional design process. Also Structural design requires effective length of Piles having long unsupported length thro’ reclaimed soil.
Kindly throw some light on how we handle foundations for Tall Building in India.
From Investigations, Interpretation, Analysis and Design View Point.
Would like to learn more on the Interaction Analysis, if carried out in India.

4. Requirements to protect Non-Structural Elements from collapse/outside fall during EQ. Requirements for Services (HVAC, MEP etc.) to prevent hazards during EQ.

5. How to identify need for Construction Stage Analysis


It is great to have such a great opportunity to learn seating at Home.
Thanks to SEFI


K. N. Sheth
Dharmsinh Desai University
Nadiad.






-- ­­

Posted via Email

[jshukla]

Dear Forum Friends,

It seems that many of us are interested in knowing piled raft analysis methods. I am posting here International Society of Soil Mechanics and Geotechnical Engineering TC report which describes basic methodology. However it mostly furnishes the geotechnical procedures. http://www.sendspace.com/file/2qyua8

another report on CPRF (Combined piled raft foundation) can be obtained from following link.

http://www.issmge.org/attachments/article/157/ISSMGE-TC-212-Deep-Foundations-Annual-Report-2012.pdf

I hope it append the forum knowledge base. I love questions.

regards,

jay