Reinforcement required (per meter width, approximate): [ d = t - cover - \phi/2 = 1500 - 75 - 16 = 1409 , \textmm ] [ A_s = \fracM_Ed0.87 f_yk \times 0.9 d = \frac4473\times10^60.87\times500\times0.9\times1409 \times (1/7m)?? ] Let’s compute :
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: Tower Crane Foundation Design Calculation Example
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 ] Reinforcement required (per meter width, approximate): [ d
This exceeds (q_allow = 150 , \textkPa) → or must be deepened or widened. 4.5 Revised foundation size Try (L = B = 7.0 , \textm, t = 1.5 , \textm): For simplicity, take average pressure = (204
[ 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 ]
Reinforcement required (per meter width, approximate): [ d = t - cover - \phi/2 = 1500 - 75 - 16 = 1409 , \textmm ] [ A_s = \fracM_Ed0.87 f_yk \times 0.9 d = \frac4473\times10^60.87\times500\times0.9\times1409 \times (1/7m)?? ] Let’s compute :
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:
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 ]
This exceeds (q_allow = 150 , \textkPa) → or must be deepened or widened. 4.5 Revised foundation size Try (L = B = 7.0 , \textm, t = 1.5 , \textm):
[ 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 ]
