Effective width (L') (ULS) with (e = M_d / N_total,ULS = 6300 / 2985.5 = 2.11 , \textm) [ L' = 3\times(3.5 - 2.11) = 4.17 , \textm ] [ q_max,ULS = \frac2 \times 2985.57 \times 4.17 = \frac597129.19 \approx 204.5 , \textkPa ]
Net bearing pressure at SLS = (q_max \approx 132.2 , \textkPa) Influence factor (I_s) for square footing ≈ 0.88 [ \delta = q_max \times B \times \frac1-\nu^2E_s \times I_s = 132.2 \times 7 \times \frac1-0.122530000 \times 0.88 ] [ \delta \approx 132.2\times7\times0.8775/30000\times0.88 = 0.0239 , \textm = 23.9 , \textmm ] Tower Crane Foundation Design Calculation Example
For a 6 m square foundation, (L/6 = 1.0 , \textm). Since (e > L/6) (2.176 > 1.0), the resultant lies outside the middle third → partial uplift. Effective width (L' = 3 \times (L/2 - e) = 3 \times (3.0 - 2.176) = 2.472 , \textm). [ q_max = \frac2 \times N_totalB \times L' = \frac2 \times 19306.0 \times 2.472 = \frac386014.832 \approx 260.3 , \textkPa ] Effective width (L') (ULS) with (e = M_d
Overturning moment includes wind, eccentric lifting, and dynamic effects. 4. Foundation Sizing – Bearing Pressure Check (SLS) 4.1 Self-weight of foundation [ W_conc = L \times B \times t \times \gamma_conc = 6.0 \times 6.0 \times 1.2 \times 25 = 1080 , \textkN ] Soil above base (ignore – removed during excavation and not replaced for simplicity – conservative). 4.2 Total vertical load (SLS) [ N_total = V_k + W_conc = 850 + 1080 = 1930 , \textkN ] 4.3 Eccentricity [ e = \fracM_kN_total = \frac42001930 = 2.176 , \textm ] [ q_max = \frac2 \times N_totalB \times L'
Moment about column edge = pressure resultant × lever arm. Use trapezoidal distribution? For simplicity, take average pressure = (204.5 + 0)/2? No, partial uplift. Actually, use effective width method:
