A=Ptotalqacap A equals the fraction with numerator cap P sub t o t a l end-sub and denominator q sub a end-fraction Ptotalcap P sub t o t a l end-sub
Required steel area (d = 1.5 m – cover 0.075 m – 0.025 m = 1.4 m) As = M / (0.87 fy z) ≈ 783×10⁶ / (0.87×500×0.9×1,400) ≈ 1,430 mm²/m
and the structural safety factors against overturning (typically >1.5is greater than 1.5 ) are satisfied. Structural Reinforcement Design tower crane foundation design calculation example link
Friction coefficient (concrete on soil) typically μ = 0.35. Resisting friction force = V_total × μ = 2,550 × 0.35 = 892.5 kN. Sliding force H = 150 kN. SF sliding = 892.5 / 150 = 5.95 → OK.
$$ F_S,OT = \frac\textRestoring Moment\textOverturning Moment = \fracP_total \times (B/2)M_total $$ A=Ptotalqacap A equals the fraction with numerator cap
The provided link ( engineeringexamples.com/... ) illustrates an automated version of these calculations.
Provide 25mm diameter bars spaced at 350mm centers ( Sliding force H = 150 kN
To prevent the foundation from lifting off the ground entirely, the eccentricity should ideally fall within the middle third of the base (
Allowable qall=200 kPaAllowable q sub a l l end-sub equals 200 kPa ( FAIL ).
Once the foundation's dimensions are verified for stability with the soil, the concrete footing itself must be structurally designed to withstand the internal forces. This involves two key checks: