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 ]
Maximum moment at crane column face (assume column base plate 2 m × 2 m): Tower Crane Foundation Design Calculation Example
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: For a 6 m square foundation, (L/6 = 1
[ W_conc = 7\times7\times1.5\times25 = 1837.5 , \textkN ] [ N_total = 850 + 1837.5 = 2687.5 , \textkN ] [ e = 4200 / 2687.5 = 1.563 , \textm ] [ L/6 = 7/6 = 1.167 , \textm; \quad e > L/6 \rightarrow \textstill partial uplift ] [ L' = 3\times(3.5 - 1.563) = 5.811 , \textm ] [ q_max = \frac2\times2687.57 \times 5.811 = \frac537540.677 \approx 132.2 , \textkPa < 150 , \textkPa \quad \text✓ OK ] [ q_max = \frac2 \times N_totalB \times L'
For 7 m square, 2.5 m projection, (M_Ed \approx 0.5 \times q_max \times B \times c^2 = 0.5 \times 204.5 \times 7 \times 6.25 = 4473 , \textkNm) – that’s total moment.
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 ]
Maximum moment at crane column face (assume column base plate 2 m × 2 m):
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:
[ W_conc = 7\times7\times1.5\times25 = 1837.5 , \textkN ] [ N_total = 850 + 1837.5 = 2687.5 , \textkN ] [ e = 4200 / 2687.5 = 1.563 , \textm ] [ L/6 = 7/6 = 1.167 , \textm; \quad e > L/6 \rightarrow \textstill partial uplift ] [ L' = 3\times(3.5 - 1.563) = 5.811 , \textm ] [ q_max = \frac2\times2687.57 \times 5.811 = \frac537540.677 \approx 132.2 , \textkPa < 150 , \textkPa \quad \text✓ OK ]
For 7 m square, 2.5 m projection, (M_Ed \approx 0.5 \times q_max \times B \times c^2 = 0.5 \times 204.5 \times 7 \times 6.25 = 4473 , \textkNm) – that’s total moment.