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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 2212

Posted: Mon Apr 19, 2010 7:15 am Post subject: Teng's curve 


Foundation Design by Wayne C Teng
Yes ,This is very good Book. This book has been in use by the designers / structural consultants/Geotech consultants
since long, may be from 50's/60's.Very popular & practical due to availability of curves/tables.
This book ,surely ,enrich the domain of Civil Engg. Libraries .
vikramjeet
Dear Sefians
Foundation design by Wayne C.Teng is a very usefull book on Siol Mechanics and foundation engg and it is woth to buy the book at any cost.
er.Balaji venkateswaran
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haridevender SEFI Regulars
Joined: 25 Mar 2011 Posts: 31

Posted: Wed Jun 01, 2011 4:53 pm Post subject: 


Dear all, Please anybody can give the mathematical modelling equation for the calculation of x and y, in Zone II.
Hari Devender


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sudhansh09 SEFI Member
Joined: 21 Aug 2009 Posts: 6

Posted: Thu Jun 02, 2011 3:51 pm Post subject: 


Dear haridevender,
You might be asking for base pressure redistribution.
Here is table to find out value of k,
from book " Roark's Formulas for stress and strain"
 e1=eb/B  e2=el/L  0  0.05  0.1  0.15  0.175  0.2  0.225  0.25  0.275  0.3  0.325  0.35  0.375  0.4  0  1  1.3  1.6  1.9  2.05  2.22  2.43  2.67  2.96  3.33  3.81  4.44  5.33  6.67  0.05  1.3  1.6  1.9  2.21  2.38  2.58  2.81  3.09  3.43  3.87  4.41  5.16  6.17  7.73  0.1  1.6  1.9  2.2  2.56  2.76  2.99  3.27  3.6  3.99  4.48  5.14  5.99  7.16  9  0.15  1.9  2.21  2.56  2.96  3.22  3.51  3.84  4.22  4.66  5.28  6.03  7.04  8.45  10.6  0.175  2.05  2.38  2.76  3.22  3.5  3.81  4.16  4.55  5.08  5.73  6.55  7.66  9.17  11.5  0.2  2.22  2.58  2.99  3.51  3.81  4.13  4.5  4.97  5.54  6.24  7.12  8.33  9.98   0.225  2.43  2.81  3.27  3.84  4.16  4.5  4.93  5.18  6.05  6.83  7.82  9.13  10.9   0.25  2.67  3.09  3.6  4.22  4.55  4.97  5.48  6  6.67  7.5  8.57  10  12   0.275  2.96  3.43  3.99  4.66  5.08  5.54  6.05  6.67  7.41  8.37  9.55  11.1    0.3  3.33  3.87  4.48  5.28  5.73  6.24  6.83  7.5  8.37  9.37  10.8     0.325  3.81  4.41  5.14  6.03  6.55  7.12  7.82  8.57  9.55  10.8      0.35  4.44  5.16  5.99  7.04  7.66  8.33  9.13  10  11.1       0.375  5.33  6.17  7.16  8.45  9.17  9.98  10.9  12        0.4  6.67  7.73  9  10.6  11.5          
Thanks & Regards
sudhanshu
Accrete


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haridevender SEFI Regulars
Joined: 25 Mar 2011 Posts: 31

Posted: Thu Jun 02, 2011 4:18 pm Post subject: 


Dear Sir,
Thanks for providing the K Values. Please tell me in which chapter, above table has been taken.
But I need of Mathematical modelling equations to find out the x and y values which are zone II of Teng's Curves, to findout the contact area of the footing under the application of eccentric loading in either directions simultaneously.
Thank you


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ibarua General Sponsor
Joined: 26 Jan 2003 Posts: 1039

Posted: Mon Jun 06, 2011 8:57 am Post subject: Teng's curve 


6th June 2011
The method of 'Least Squares Curve Fitting' is a very useful procedure for obtaining an equation for any curve, given a set of known 'x' and 'y' values.
I had written a Qbasic program for solving this problem, many years ago. I could send it to you if you let me have your email ID.
Indrajit Barua.
On Thu, 02 Jun 2011 08:48:44 +0530 "haridevender" <forum@sefindia.org> wrote
Quote:  Dear all, Please anybody can give the mathematical modelling equation for the calculation of x and y, in Zone II.
Hari Devender

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ibarua General Sponsor
Joined: 26 Jan 2003 Posts: 1039

Posted: Mon Jun 06, 2011 9:11 am Post subject: Teng's curve 


6th June 2011
Re.: query about Teng's curve
In case of foundations subject to uplift, use may be made of the method prescribed in 'Steel Designers' Manual', explained briefly here as follows:
Loaded length = 3*y = 3*(L/2e)
Maximum edge pressure, p(max) = 2*W/(3*B*y),
where: W = total axial load on foundation including self wt. of fdn.
B = width of fdn.
e = M/W
Indrajit Barua.
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jiwaji ...
Joined: 08 Apr 2009 Posts: 75 Location: Jamshedpur

Posted: Tue Jun 07, 2011 4:33 am Post subject: Teng's curve 


Dear Sir
Would it possiblefor you to help me find /give me similar equations for a closed solution, for bases subjected to tension uplift due to eccentricties (greater than B/6 and L/6) about both orthogonal axes, ie biaxial bending with tension? I would be grateful for the same.
Thanks and regards
Jiwaji
"ibarua" <forum@sefindia.org>
06/06/2011 07:41 PM Please respond to
general@sefindia.org
To
general@sefindia.org cc
Subject
[SEFI] Re: Teng's curve
6th June 2011
Re.: query about Teng's curve
In case of foundations subject to uplift, use may be made of the method prescribed in 'Steel Designers' Manual', explained briefly here as follows:
Loaded length = 3*y = 3*(L/2e)
Maximum edge pressure, p(max) = 2*W/(3*B*y),
where: W = total axial load on foundation including self wt. of fdn.
B = width of fdn.
e = M/W
Indrajit Barua.


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ibarua General Sponsor
Joined: 26 Jan 2003 Posts: 1039

Posted: Wed Jun 08, 2011 6:31 am Post subject: Teng's curve 


8th June 2011
You could perhaps treat the actions in the two cases separately and then superimpose the results.
Generally, for a loading eccentric about both axes:
If 'eL' and 'eB' are the eccentricities of the load 'W' with regard to 'L' and 'B' respectively, then:
p(max) = W/(B*L) *(1+ 6*eL/L + 6*eB/B)
p(min) = W/(B*L) *(1 6*eL/L  6*eB/B)
Another way could be to compute the resultant moment and align the foundation in the direction of the resultant moment.
Indrajit Barua
However, I have not yet come across a situation when a foundations has uplifts in two directions.
Indrajit Barua.
On Tue, 07 Jun 2011 11:58:39 +0530 "jiwaji" <forum@sefindia.org> wrote
[quote] Dear Sir
Would it possiblefor you to help me find /give me similar equations for a closed solution, for bases subjected to tension uplift due to eccentricties (greater than B/6 and L/6) about both orthogonal axes, ie biaxial bending with tension? I would be grateful for the same.
Thanks and regards
Jiwaji
"ibarua" <forum@sefindia.org>
06/06/2011 07:41 PM Please respond to
general@sefindia.org
To
general@sefindia.org cc
Subject
[SEFI] Re: Teng's curve
6th June 2011
Re.: query about Teng's curve
In case of foundations subject to uplift, use may be made of the method prescribed in 'Steel Designers' Manual', explained briefly here as follows:
Loaded length = 3*y = 3*(L/2e)
Maximum edge pressure, p(max) = 2*W/(3*B*y),
where: W = total axial load on foundation including self wt. of fdn.
B = width of fdn.
e = M/W
Indrajit Barua.

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JVCSNL ...
Joined: 26 Jan 2003 Posts: 159

Posted: Thu Jun 09, 2011 3:21 am Post subject: Teng's curve 


We can not treat the effects of moments in individual direction and then superimpose. The large moments in both the direction is usually a short term loading case (due to EQ force) for many industrial plant structures and tall equipment foundations and hence, we do not align the foundation in the direction of resultant moments as most of the times, these moments would not be present.
To answer Mr. Jiwaji's query, there is no unified equation which can take care of any combination of eccentricity in X and Y direction. It may be possible, but so far I have not seen literature giving these equations. Please note that the moment there is tension (ve bearing pressure) at any of the corner, one has to analyze the foundation considering the neutral axis which is not orthogonal to any direction.
If you refer to Teng's curve, for eccentricity within the Kern, the pressure distribution is linear (say x to power 1). As eccentricity increases, the behavior starts to become non linear and the power to X increases continuously. In the high eccentricity zones (ex/Lx and ey/Ly more than 0.25), the equation seems to be of power 3 or 4 and reaches to infinity when eccentricity value reaches near the foundation edges.
Since, these equations were not available, I solved the problem with numerical approach and the literature on this is already available on SEFI (may be on page 3 of this topic). You may refer to the same for more about foundations with large moments in both the directions.
Regards,
Jignesh V Chokshi
Quote:  Quote:  Quote:  forum@sefindia.org 08062011 >>>



8th June 2011
You could perhaps treat the actions in the two cases separately and then superimpose the results.
Generally, for a loading eccentric about both axes:
If 'eL' and 'eB' are the eccentricities of the load 'W' with regard to 'L' and 'B' respectively, then:
p(max) = W/(B*L) *(1+ 6*eL/L + 6*eB/B)
p(min) = W/(B*L) *(1 6*eL/L  6*eB/B)
Another way could be to compute the resultant moment and align the foundation in the direction of the resultant moment.
Indrajit Barua
However, I have not yet come across a situation when a foundations has uplifts in two directions.
Indrajit Barua.
On Tue, 07 Jun 2011 11:58:39 +0530 "jiwaji" wrote
Quote:  Dear Sir
Would it possiblefor you to help me find /give me similar equations for a closed solution, for bases subjected to tension uplift due to eccentricties (greater than B/6 and L/6) about both orthogonal axes, ie biaxial bending with tension? I would be grateful for the same.
Thanks and regards
Jiwaji
"ibarua"
06/06/2011 07:41 PM Please respond to
general@sefindia.org (general@sefindia.org)
To
general@sefindia.org (general@sefindia.org) cc
Subject
[SEFI] Re: Teng's curve
6th June 2011
Re.: query about Teng's curve
In case of foundations subject to uplift, use may be made of the method prescribed in 'Steel Designers' Manual', explained briefly here as follows:
Loaded length = 3*y = 3*(L/2e)
Maximum edge pressure, p(max) = 2*W/(3*B*y),
where: W = total axial load on foundation including self wt. of fdn.
B = width of fdn.
e = M/W
Indrajit Barua.


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jiwaji ...
Joined: 08 Apr 2009 Posts: 75 Location: Jamshedpur

Posted: Thu Jun 09, 2011 4:31 am Post subject: Teng's curve 


Sir
The equations given by you hold only ecc less than 1/6 th the respective base directions, as full area is assumed in contact in their derivation. My query was for when the only when a part of the area is in contact, ie the NA is inclined to the principal directions of moments, and inside the footing area.
These equations may be the basis of Teng's charts, and one would like to use them for developing EXCEL or mathcad sheets.
Sir, these situations ar often encountered when diect loadings are relatively light, dominant horizontal thrusts (specified by vendors in a variety of combinations) are to be resisted, tiebeams are a luxury and column locations are guided by technological inputs, ie irregular mechanical layouts resulting in high biaxial eccentricities. One is often called upon to locate such additional columns in an existing Plant for various reasons, where choice of location by structural engineer is unthinkable.
I would be grateful any information on such equations, based is made available.
Regards
Jiwaji Desai
"ibarua" <forum@sefindia.org>
06/08/2011 09:23 PM Please respond to
general@sefindia.org
To
general@sefindia.org cc
Subject
[SEFI] Re: Teng's curve
8th June 2011
You could perhaps treat the actions in the two cases separately and then superimpose the results.
Generally, for a loading eccentric about both axes:
If 'eL' and 'eB' are the eccentricities of the load 'W' with regard to 'L' and 'B' respectively, then:
p(max) = W/(B*L) *(1+ 6*eL/L + 6*eB/B)
p(min) = W/(B*L) *(1 6*eL/L  6*eB/B)
Another way could be to compute the resultant moment and align the foundation in the direction of the resultant moment.
Indrajit Barua
However, I have not yet come across a situation when a foundations has uplifts in two directions.
Indrajit Barua.
On Tue, 07 Jun 2011 11:58:39 +0530 "jiwaji" <forum@sefindia.org> wrote
Quote:  Dear Sir
Would it possiblefor you to help me find /give me similar equations for a closed solution, for bases subjected to tension uplift due to eccentricties (greater than B/6 and L/6) about both orthogonal axes, ie biaxial bending with tension? I would be grateful for the same.
Thanks and regards
Jiwaji
"ibarua" <forum@sefindia.org>
06/06/2011 07:41 PM Please respond to
general@sefindia.org
To
general@sefindia.org cc
Subject
[SEFI] Re: Teng's curve
6th June 2011
Re.: query about Teng's curve
In case of foundations subject to uplift, use may be made of the method prescribed in 'Steel Designers' Manual', explained briefly here as follows:
Loaded length = 3*y = 3*(L/2e)
Maximum edge pressure, p(max) = 2*W/(3*B*y),
where: W = total axial load on foundation including self wt. of fdn.
B = width of fdn.
e = M/W
Indrajit Barua.




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