This computes the horizontal displacement at the top of a wall caused by rotation due to compression of the soil under the toe.
You must enter the modulus of subgrade reaction. The program divides the soil bearing stress in psi by the soil modulus (psi/inch) to quantify the displacement at the footing. Then, assuming the wall and footing are rigid, the program determines the horizontal displacement at the top of the wall based on the amount of rotation experienced at the footing.
Note: This is approximate due to variation in soil pressure under the footing, and does not include deflection of the stem due to lateral earth pressures. (The latter is usually less than the "tilt" deflection, and if desired, must be done by hand calculation, requiring investigation of cracked and uncracked moments of inertia.)
To mobilize the active pressure in retained earth, it is often considered that the deflection at top must be greater than or equal to 0.005 x Htotal.