Check for sliding (pad and strip base:ACI 318)
The check for sliding is carried out for pad foundations only.
If there is no horizontal force acting on foundation check for sliding is not required.
Resultant Force on foundation:
Hd = √[(Fx,sup)2 + (Fy,sup)2]
Resultant Force Angle αHd = tan-1 [(Fy,sup / Fx,sup)]
where
Fx,sup = horizontal force acting on support in X-dir. (from analysis)
Fy,sup = horizontal force acting on support in Y-dir. (from analysis)
Resistance to sliding due to base friction:
Hfriction = [-P + Fswt] * tanδ
where
δ = design base friction – user input
Passive pressure coefficient:
Kp = (1+sinΦ’) / (1-sinΦ’)
where
Φ’ = design shear strength of soil – user input
Passive resistance of soil in X direction:
Hxpas = 0.5*Kp*(h2 +2*h*hsoil)*Lx* ρsoil
Passive resistance of soil in Y direction:
Hypas = 0.5*Kp*(h2 +2*h*hsoil)*Ly* ρsoil
Resultant Passive Resistance:
Hres,pas = abs(Hxpas*cos αHd) + abs(Hypas*sin αHd)
Total resistance to sliding:
RHd = (Hfriction + Hres,pas) / 1.5
If
RHd ≥ Hd
The check for stability against sliding passes