Design of Isolated Footing Footing No. 1 Joint No. 1 Load Case No. 1,2 1. Support Reactions a. Dead Load, DL Fx = kn Fy = 117.92 kn Fz = kn Mx = kn My = kn Mz = kn b. Live Load, LL Fx = kn Fy = 27.15 kn Fz = kn Mx = kn My = kn Mz = kn c. Ultimate Load (1.4 DL + 1.7LL), Pu Pu = 211.243 kn 2. Soil Bearing Capacity, SBC SBC = 100 Kpa 3. Preliminary Footing Dimension Assume weight of footing, wt = 8% of Fy dead load + Fy live load wt = 11.606 kn Area required, a = dead load + F live load + wt. of ftg SBC a = 1.5668 sq.m Assume footing width, W = 1.2 m length, L = 1.3056 m say W = 1.2 m L = 1.4 m Actual area, A = 1.68 sq.m 4. Net Ultimate Upward Soil Pressure, qu Net upward soil pressure, qu = 1.4(Fy dead load) + 1.7(Fy live load) Actual area qu = 125.74 kpa Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy liv Fy dead load + Fy live load qa = 145.615 kpa qa>qu, SAFE!
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Design of Isolated Footing
Footing No. 1Joint No. 1Load Case No. 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 117.92 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 27.15 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 211.243 kn
2. Soil Bearing Capacity, SBC
SBC = 100 Kpa
3. Preliminary Footing Dimension
Assume weight of footing, wt = 8% of Fy dead load + Fy live load wt = 11.6056 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 1.56676 sq.m
Assume footing width, W = 1.2 mlength, L = 1.30563 m
say W = 1.2 mL = 1.4 m
Actual area, A = 1.68 sq.m
4. Net Ultimate Upward Soil Pressure, qu
Net upward soil pressure, qu = 1.4(Fy dead load) + 1.7(Fy live load)Actual area
qu = 125.74 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 145.6145 kpa
qa>qu, SAFE!
5. Check Punching Shear
Width of square column, c = 200 mmBar diameter, Ab = 16 mm
Assume footing thickness, t = 250 mmEffective depth, d = 167 mm
Actual punching shear stress, Vn = VuF bod
where:Ultimate punching shear, Vu =
Vu = 194.307 kn
Vn = 1.46557 mpa
Allow. punching shear stress, Vc = sqrt of F'c/3
where:F'c = 20.7 mpa
Vc = 1.51658 mpa
Vc>Vn, SAFE!
6. Check Beam Shear
Footing edge to d distance from face of support, a = 433 mm
Actual beam shear stress, Vn = VuF Wd
where:Ultimate beam shear, Vu = qu(W)(a)
Vu = 65.3344 kn
Vn = 0.384 mpa
Allow. punching shear stress, Vc = sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.75829 mpa
Vc>Vn, SAFE!
7. Check Footing Area
Footing width, W = 1.2 mlength, L = 1.4 m
thickness, t = 250 mm
Actual wt.of footing = 9.89 knTotal weight = 154.96 kn
Area required = 1.550 sq.m
Actual Area > Required Area, SAFE!
qu[A-(c+d)^2]
8. Required Steel Area, As a. For long direction
Dist. of footing edge to face of support, X = 0.6 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 27.15981 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p27.1598142857143 1.2 167 275 20.7 0.04356119 0.0447 0.0034
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.00509 pmax = 0.0280
pmin>p, use pmin
Steel area, As = pWdp = 0.00509
As = 1020 sq.mmN = 5.07323
Use 7 pcs --- 16 mm. dia. reinforcing bars
b. For short directionDist. of footing edge to face of support, Z = 1 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 88.01792 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p88.0179166666667 1.4 151 275 20.7 0.14800497 0.1638 0.0123
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.00509 pmax = 0.0280
use p
Steel area, As = pLdp = 0.00509
As = 1076.24 sq.mmN = 5.35275
Use 6 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 993.45 sq.mmN1 = 4.941
For center strip, use 5 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 82.7875 sq.mm
N2 = 0.41175
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
2/(b+1)
outer strip center strip outer strip1.2 m
1.2 m
reinforced concrete square
column
Design of Isolated Footing
Footing No. 2Joint No. 2Load Case No. 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 232.1 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 74.35 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 451.335 kn
2. Soil Bearing Capacity, SBC
SBC = 100 Kpa
3. Preliminary Footing Dimension
ume weight of footing, wt = 8% of Fy dead load + Fy live load wt = 24.516 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 3.30966 sq.m
Assume footing width, W = 1.7 mlength, L = 1.946859 m
say W = 1.7 mL = 1.85 m
Actual area, A = 3.145 sq.m
4. Net Ultimate Upward Soil Pressure, qu
upward soil pressure, qu = 1.4(Fy dead load) + 1.7(Fy live load)Actual area
qu = 143.5087 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 147.2785 kpa
qa>qu, SAFE!
5. Check Punching Shear
Width of square column, c = 200 mmBar diameter, Ab = 16 mm
sume footing thickness, t = 375 mmEffective depth, d = 292 mm
punching shear stress, Vn = VuF bod
where:timate punching shear, Vu =
Vu = 416.5967 kn
Vn = 1.417628 mpa
Allow. punching shear stres sqrt of F'c/3
where:F'c = 20.7 mpa
Vc = 1.516575 mpa
Vc>Vn, SAFE!
6. Check Beam Shear
oting edge to d distance from face of support, a = 533 mm