Rectangular Pier Spread Footing Analysis Calculator

This calculator will analysis the rigid rectangular spread footings with up to 8 total piers, and for either uniaxial or biaxial resultant eccentricities. Overturning sliding, and uplift stability checks are made when applicable, and resulting gross soil bearing pressures at the four (4) corners of the footing are calculated. The maximum net soil bearing pressure is also determined.

Notes:
Calculations assumes that the spread footing is in fact "rigid", so that the bearing pressure is distributed linearly on a homogeneous soil. (Note: the actual footing is generally not "rigid", nor is the pressure beaneth it distributed linearly. However, it has been found that solutions using the assumed "rigid" concept are adequate and generally result in a conservative design.)

A specified permissible value for the factor of safety against overturning. However, a minimum value of 1.5 to 2.0 is suggested, based upon the particular conditions.

For Assumed Rigid Footing with from 1 To 8 Piers
Subjected to Uniaxial or Biaxial Eccentricity
Variables:
Footing Data: Footing Length, L = ft.
Footing Width, B = ft.
Footing Thickness, T = ft.
Concrete Unit Wt., gc = kcf
Soil Depth, D = ft.
Soil Unit Wt., gs = kcf
Pass. Press. Coef., Kp =
Coef. of Base Friction, m =
Uniform Surcharge, Q = ksf
Number of Piers =
Xp (ft.) =
Yp (ft.) =
Lpx (ft.) =
Lpy (ft.) =
h (ft.) =
Pz (k) =
Hx (k) =
Hy (k) =
Mx (ft-k) =
My (ft-k) =
FOOTING PLAN
Results:
Nomenclature for Biaxial Eccentricity:
Total Resultant Load and Eccentricitie SPz =
kips
ex =
ey =
Overturning Check:
SMrx =
ft-kips
SMox =
ft-kips
FS(ot)x =
SMry =
ft-kips
SMoy =
ft-kips
FS(ot)y =
Sliding Check: Pass(x) =
kips
Frict(x) =
kips
FS(slid)x =
Passive(y) =
kips
Frict(y) =
kips
FS(slid)y =
Uplift Check:
SPz(down) =
kips
SPz(uplift) =
kips
FS(uplift) = Bearing Length and % Bearing Area:
Dist. x =
ft.
Dist. y =
ft.
ft.
ft.
%Brg. Area = %
Biaxial Case =
Gross Soil Bearing Corner Pressures:
P1 =
ksf
P2 =
ksf
P3 =
ksf
P4 =
ksf  Maximum Net Soil Pressure:
Pmax(net) = Pmax(gross)-(D+T)*gs
Pmax(net) = ksf    Home Engineering Book Store Engineering Forum Applications and Design Beam Deflections and Stress Bearing Apps, Specs & Data Belt Design Data Calcs Civil Engineering Design & Manufacturability Electric Motor Alternators