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Teng's curve
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aapkamitrgss
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PostPosted: Thu Jun 18, 2009 6:01 am    Post subject: Teng's curve Reply with quote

i was designing foundations for towers... i came across the name teng's curve. can anybody explain this and provide me the reference and where it has been used.
If a image of teng's curve or any literature i can get here, will be very helpful...

Thanks in advance.
Gurnam Singh
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fungineer
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PostPosted: Thu Jun 18, 2009 6:11 am    Post subject: Reply with quote

Teng's Chart is used when the foundation is under tension (uplift in case of towers). In such cases, the effective area of the foundation is reduced and the pressure is recalculated.

Normal Case P/A+M/Z
Uplift Case P/A1+M/Z

Where A1 is the reduced area.
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PNP
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aapkamitrgss
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PostPosted: Thu Jun 18, 2009 6:45 am    Post subject: Reply with quote

is there any reference..
any image of the teng's curve may please be uploaded?
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JVCSNL
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PostPosted: Thu Jun 18, 2009 6:56 am    Post subject: Teng's curve Reply with quote

Dear Mr. Gurnam Singh,

Teng's curves are very popular in foundation engineering.

The reference is W C Teng's foundation design book. (Might be out of print). Other reading material is Hansen and Peck book.

Almost all the foundations are subjected to axial force and bending moments about both the axes. You may recall from the principles of direct and bending stresses that when the application of load is within the kern of the foundation, bearing pressure (P/A+/- Mi/Zi) below footing is compressive in nature.

However, when the load is outside kern, the bearing pressure in footing is not compressive within footing and there exists negative pressure at one or more corners.

Since, there is no medium between footing pad and soil to resist this tension (called uplift) the portion in negative area can not be considered effective. In this case, the entire load shall be taken by the portion of footing in contact with soil. Since, in all conditions, the equilibrium shall occur, the bearing pressures gets modified and location of neutral axis also shifts.

Though, this concept looks simple in nature, it is very difficult to obtain modified pressure values and location of neutral axis after satisfying equilibrium conditions.

Teng's chart provides the factor to calculate modified pressure based on the eccentricity of the loading point for rectangular footings. Teng's charts are divided in 4 zones and for each zone the factor and formulae to calculate modified pressure is given. It shall be noted that these charts are only for calculation of bearing pressure for rectangular footing. The stability checks needs to be applied as usual.

Regards,

Jignesh Chokshi




Quote:
Quote:
Quote:
forum@sefindia.org 18-06-2009 >>>

i was designing foundations for towers... i came across the name teng's curve. can anybody explain this and provide me the reference and where it has been used.
If a image of teng's curve or any literature i can get here, will be very helpful...

Thanks in advance.
Gurnam Singh

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jiwaji
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PostPosted: Thu Jun 18, 2009 8:48 am    Post subject: Teng's curve Reply with quote

Dear Mr Choksi
I will be greatly obliged if you could mail me the Teng's full charts (4-zones) to my email id jydesai@tce.co.in
Regards
Jiwaji Y Desai
DGM (C&S)
TCE Jamshedpur


"JVCSNL" <forum@sefindia.org>  
06/18/2009 12:47 PM    Please respond to
general@sefindia.org

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general@sefindia.org   cc
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[SEFI] Re: Teng's curve




Dear Mr. Gurnam Singh,

Teng's curves are very popular in foundation engineering.

The reference is W C Teng's foundation design book. (Might be out of print). Other reading material is Hansen and Peck book.

Almost all the foundations are subjected to axial force and bending moments about both the axes. You may recall from the principles of direct and bending stresses that when the application of load is within the kern of the foundation, bearing pressure (P/A+/- Mi/Zi) below footing is compressive in nature.

However, when the load is outside kern, the bearing pressure in footing is not compressive within footing and there exists negative pressure at one or more corners.

Since, there is no medium between footing pad and soil to resist this tension (called uplift) the portion in negative area can not be considered effective. In this case, the entire load shall be taken by the portion of footing in contact with soil. Since, in all conditions, the equilibrium shall occur, the bearing pressures gets modified and location of neutral axis also shifts.

Though, this concept looks simple in nature, it is very difficult to obtain modified pressure values and location of neutral axis after satisfying equilibrium conditions.

Teng's chart provides the factor to calculate modified pressure based on the eccentricity of the loading point for rectangular footings. Teng's charts are divided in 4 zones and for each zone the factor and formulae to calculate modified pressure is given. It shall be noted that these charts are only for calculation of bearing pressure for rectangular footing. The stability checks needs to be applied as usual.

Regards,

Jignesh Chokshi





Quote:

Quote:

Quote:
forum@sefindia.org 18-06-2009 >>>




i was designing foundations for towers... i came across the name teng's curve. can anybody explain this and provide me the reference and where it has been used.
If a image of teng's curve or any literature i can get here, will be very helpful...

Thanks in advance.
Gurnam Singh







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Dr. N. Subramanian
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PostPosted: Thu Jun 18, 2009 3:12 pm    Post subject: Teng's curve Reply with quote

Dear Er Gurnam Singh,It may be available in the book Teng, W.C. (1962) Foundation Design, Prentice-Hall Inc., PHI had an Indian edition- which is available with me in India. Sorry I can not send you the chart, as I am now in USA.

But since you are doing the design of tower foundations, I suggest you to refer to my paper in ICJ:


1) Subramanian N., and Vasanthi, V., Design of Tower Foundations, The Indian Concrete Journal, Vol.64, No.3, March 1990, pp. 135-141


The following books also may be of help:
2)Varghese, P.C., Design of Reinforced Concrete Foundations, Prentice Hall Of India, 2005, See Chapter 19 on Tower Foundation3) Murthy, S.S. and Santhakumar, A.R., Transmission line structures, McGraw hill, Singapore, 1990.Best wishesSubramanian
Quote:

From: aapkamitrgss <forum@sefindia.org>
Subject: [SEFI] Teng's curve
To: general@sefindia.org
Date: Thursday, June 18, 2009, 11:31 AM

i was designing foundations for towers... i came across the name teng's curve. can anybody explain this and provide me the reference and where it has been used.
If a image of teng's curve or any literature i can get here, will be very helpful...

Thanks in advance.
Gurnam Singh
     



     


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Last edited by Dr. N. Subramanian on Thu Oct 20, 2011 4:26 pm; edited 1 time in total
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PostPosted: Thu Jun 18, 2009 11:08 pm    Post subject: Teng's curve Reply with quote

Hi Gurnam,

I was in tower industry for quite a while, in India as well as overseas, but never heard of Teng's curves. If you have any foundation-specific question, pl. email it. I'll try to respond.


Best regards,

Rajendra (Raj) Lele

  
P Please consider the environment before printing this e-mail or any attachment/s.



From: aapkamitrgss <forum@sefindia.org>
To: general@sefindia.org
Sent: Thursday, 18 June, 2009 4:01:06 PM
Subject: [SEFI] Teng's curve

i was designing foundations for towers... i came across the name teng's curve. can anybody explain this and provide me the reference and where it has been used.
If a image of teng's curve or any literature i can get here, will be very helpful...

Thanks in advance.
Gurnam Singh








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patole
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PostPosted: Fri Jun 19, 2009 7:47 am    Post subject: Teng's curve Reply with quote

Friends,

Pl. see attached Teng's charts. These charts are use to calculate the contact area of foundation under vertical load + biaxial bending conditions. There is one chart with four graphs for four different conditions. Also this will provide you different formulas for calculating Maximum pressure under different conditions.


Pl. let me know if you need any further information on this


Vivek Patole


DCE
Chemtex India

On Fri, Jun 19, 2009 at 9:02 AM, drnsmani <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote]            Dear Er Gurnam Singh,It may be available in the book Teng, W.C. (1962) Foundation Design, Prentice-Hall Inc., PHI had an Indian edition- which is available with me in India. Sorry I can not send you the chart, as I am now in USA.

But since you are doing the design of tower foundations, I suggest you to refer to my paper in ICJ:

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1) Subramanian N., and Vasanthi, V., Design of Tower Foundations, The Indian Concrete Journal, Vol.64, No.3, March 1990, pp. 135-141


The following books also may be of help:
2)Varghese, P.C.,Design of Reinforced Concrete Foundations, Prentice Hall Of India, 2005, See Chapter 19 on Tower Foundation3) Murthy, S.S. and Santhakumar, A.R., Transmission line structures, McGraw hill, Singapore, 1990.Best wishesSubramanian
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PostPosted: Fri Jun 19, 2009 2:29 pm    Post subject: Re: Teng's curve Reply with quote

Dear Er Vivek,

Thanks for attaching Teng's chart. I think it will be useful in the case of footings subjected to ecc. loading or footings with AF and BM.

But it will not be useful for tower foundations. Hence Er. Gurnam should follow the references as listed out by me or the Manual on Transmission line Towers published by Central Board of Irrigation and Power, New Delhi-It is very old and I am not sure whether out of print.

As Er Rajendra Lele has said, I am also hearing about these Teng's curves for the first time and never used it.

Best wishes
Subramanian
[quote="patole"]Friends,

Pl. see attached Teng's charts. These charts are use to calculate the contact area of foundation under vertical load + biaxial bending conditions. There is one chart with four graphs for four different conditions. Also this will provide you different formulas for calculating Maximum pressure under different conditions.


Pl. let me know if you need any further information on this


Vivek Patole


DCE
Chemtex India

On Fri, Jun 19, 2009 at 9:02 AM, drnsmani <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Er Gurnam Singh,It may be available in the book Teng, W.C. (1962) Foundation Design, Prentice-Hall Inc., PHI had an Indian edition- which is available with me in India. Sorry I can not send you the chart, as I am now in USA.

But since you are doing the design of tower foundations, I suggest you to refer to my paper in ICJ:

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable      {mso-style-name:"Table Normal";      mso-tstyle-rowband-size:0;      mso-tstyle-colband-size:0;      mso-style-noshow:yes;      mso-style-parent:"";      mso-padding-alt:0in 5.4pt 0in 5.4pt;      mso-para-margin:0in;      mso-para-margin-bottom:.0001pt;      mso-pagination:widow-orphan;      font-size:10.0pt;      font-family:"Times New Roman";      mso-ansi-language:#0400;      mso-fareast-language:#0400;      mso-bidi-language:#0400;}
1) Subramanian N., and Vasanthi, V., Design of Tower Foundations, The Indian Concrete Journal, Vol.64, No.3, March 1990, pp. 135-141


The following books also may be of help:
2)Varghese, P.C.,Design of Reinforced Concrete Foundations, Prentice Hall Of India, 2005, See Chapter 19 on Tower Foundation3) Murthy, S.S. and Santhakumar, A.R., Transmission line structures, McGraw hill, Singapore, 1990.Best wishesSubramanian
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PostPosted: Sat Jun 20, 2009 4:41 am    Post subject: Teng's curve Reply with quote

Kindly refer to the book'Fondation Design by Wyane C Teng

All related curves for design of foundations subjected to biaxial
moments and needing redistribution of base pressures
are given in that book

vikramjeet

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