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Re: Footing design

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Sanhosh,
 
You just basically have to add or subtract the stress from the other direction. i.e.,
 
qmin = Fz / A - Mx (Ly/2) / Ixx - My (Lx/2) / Iyy
 
qmax = Fz / A + Mx (Ly/2) / Ixx - My (Lx/2) / Iyy
 
ASQuilalaJr., P.E.
 
 
 
In a message dated 12/30/05 12:34:04 A.M. Pacific Standard Time, sant527(--nospam--at)gmail.com writes:
I have a rectangular footing in the X-Y plane. There are Moments Mx ,
MY and vertical compressive force Fz. Its clear how to do for uniaxial
bending. But then for biaxial moment how to design.

The normal procedure we follow is,
We calculate maximum/minimum stress due to MX and Fz in X dir (i.e
Fzy/A + (Mx * (Lx/2))/Ixx  and Fz/A - (Mx * (Lx/2))/Ixx
Similarly we calculate maximum stress due to My and Fz in Y dir. (i.e
Fz/A + (My * (Ly/2))/Iyy  and Fy/A - (My * (Ly/2))/Iyy
And we design for shear and flexure in both the directions with the
stress calculated.

But i feel we are not taking into account of the affect of Mx in Y dir
or My in the X - dir. So can one tell some methodology

Santhosh