Chung - 2010 - Confinement of Rectangular Reinforced Concrete Col
Design of Rectangular Footing Col @ Edge_3
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Transcript of Design of Rectangular Footing Col @ Edge_3
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
ual beam shear stress, Vn = VuF Wd
where:Ultimate beam shear, Vu = qu(W)(a)
Vu = 130.0333 kn
Vn = 0.308 mpa
Allow. punching shear stres sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.758288 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
Footing width, W = 1.7 mlength, L = 1.85 m
thickness, t = 375 mm
ctual wt.of footing = 27.77 knTotal weight = 334.22 kn
Area required = 3.342 sq.m
Actual Area < Required Area, NOT SAFE!
8. Required Steel Area, As a. For long direction. of footing edge to face of support, X = 0.825 m
Bending moment, Mu = qu(W)(X)(X/2)Mu = 83.02429 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p83.0242930743 1.7 292 275 20.7 0.030745 0.0313 0.002358
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
pmin>p, use pmin
Steel area, As = pWdp = 0.00509
As = 2526.676 sq.mmN = 12.56663
Use 13 pcs --- 16 mm. dia. reinforcing bars
b. For short direction. of footing edge to face of support, Z = 1.5 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 298.6776 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p298.677573529 1.85 276 275 20.7 0.113763 0.1226 0.009231
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
use p
Steel area, As = pLdp = 0.00509
As = 2598.954 sq.mmN = 12.92611
Use 13 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 2489.139 sq.mmN1 = 12.37993
For center strip, use 13 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 109.815 sq.mm
N2 = 0.546174
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
outer strip center strip outer strip1.7 m
1.7 m
2/(b+1)
reinforced concrete square
column
Design of Isolated Footing
Footing No. 3Joint No. 3Load Case N 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 116.98 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 33.36 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 220.484 kn
2. Soil Bearing Capacity, SBC
SBC = 100 Kpa
3. Preliminary Footing Dimension
weight of footing, wt = 8% of Fy dead load + Fy live load wt = 12.0272 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 1.623672 sq.m
ume footing width, W = 1.2 mlength, L = 1.35306 m
say W = 1.2 mL = 1.35 m
Actual area, A = 1.62 sq.m
4. Net Ultimate Upward Soil Pressure, qu
ard soil pressure, qu = 1.4(Fy dead load) + 1.7(Fy live load)Actual area
qu = 136.1012 kpa
owable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 146.6569 kpa
qa>qu, SAFE!
5. Check Punching Shear
h of square column, c = 200 mmBar diameter, Ab = 16 mm
footing thickness, t = 300 mmEffective depth, d = 217 mm
hing shear stress, Vn = VuF bod
where:e punching shear, Vu =
Vu = 196.8175 kn
Vn = 1.031964 mpa
Allow. punching shear ssqrt of F'c/3
where:F'c = 20.7 mpa
Vc = 1.516575 mpa
Vc>Vn, SAFE!
6. Check Beam Shear
g edge to d distance from face of support, a = 358 mm
eam shear stress, Vn = VuF Wd
where:imate beam shear, Vu = qu(W)(a)
Vu = 58.46909 kn
Vn = 0.264 mpa
Allow. punching shear ssqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.758288 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
g width, W = 1.2 mlength, L = 1.35 m
hickness, t = 300 mm
.of footing = 11.44 kntal weight = 161.78 kn
a required = 1.618 sq.m
Actual Area > Required Area, SAFE!
8. Required Steel Area, As a. For long direction
footing edge to face of support, X = 0.575 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 26.99908 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p26.999082 1.2 217 275 20.7 0.025647 0.0260 0.001961
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
pmin>p, use pmin
Steel area, As = pWdp = 0.00509
As = 1325.436 sq.mmN = 6.592162
Use 6 pcs --- 16 mm. dia. reinforcing bars
b. For short directionfooting edge to face of support, Z = 1 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 91.86833 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p91.868333 1.35 201 275 20.7 0.090412 0.0958 0.007213
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
use p
Steel area, As = pLdp = 0.007
As = 1899.45 sq.mmN = 9.447067
Use 10 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 1787.718 sq.mmN1 = 8.891357
For center strip, use 7 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 111.7324 sq.mm
N2 = 0.55571
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
outer strip center strip outer strip1.2 m
1.2 m
2/(b+1)
reinforced concrete square
column
Design of Isolated FootingFooting No. 5
Bar diameter = 16 mmF'c = 20.7 mpafy = 275 mpa
Square col size = 300 mm1. Support Reactions
a. Dead Load, DLFx = knFy = 311.36 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 117.21 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 635.161 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 = 34.2856 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 4.62856 sq.m
Assume footing width, W = 1.1 mlength, L = 4.20778 m
say W = 2.2 mL = 2.2 m
Actual area, A = 4.84 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 = 131.232 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 148.2047 kpa
qa>qu, SAFE!
5. Check Punching Shear
Width of square column, c = 300 mmBar diameter, Ab = 16 mm
Assume footing thickness, t = 375 mmEffective depth, d = 292 mm
Actual punching shear stress, Vn = VuF bod
where:Ultimate punching shear, Vu =
Vu = 589.169 kn
Vn = 1.00244 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 = 658 mm
Actual beam shear stress, Vn = VuF Wd
where:Ultimate punching shear, Vu = qu(W)(a)
Vu = 189.971 kn
Vn = 0.696 mpa
Allow. punching shear stress, Vc = sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.75829 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
Footing width, W = 2.2 mlength, L = 2.2 m
thickness, t = 375 mm
Actual wt.of footing = 42.73 knTotal weight = 471.30 kn
Area required = 4.713 sq.m
Actual Area > Required Area, SAFE!
8. Required Steel Area, As
Dist. of footing edge to face of support, X = 0.95 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 130.2802 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p130.280182386364 2.2 292 275 20.7 0.0372801 0.0381 0.0029
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 = 3269.82 sq.mmN = 16.2627
Use 17 pcs --- 16 mm. dia. reinforcing bars e.w.
spaced @ 137.5 mm o.c.
Design of Isolated Footing
Footing No. 6Joint No. 8Load Case No. 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 117.3 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 56.24 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 259.828 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 = 13.8832 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 1.874232 sq.m
Assume footing width, W = 1.3 mlength, L = 1.441717 m
say W = 1.3 mL = 1.4 m
Actual area, A = 1.82 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 = 142.7626 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 149.7223 kpa
qa>qu, SAFE!
5. Check Punching Shear
Width of square column, c = 200 mmBar diameter, Ab = 16 mm
sume footing thickness, t = 300 mmEffective depth, d = 217 mm
punching shear stress, Vn = VuF bod
where:imate punching shear, Vu =
Vu = 235.0031 kn
Vn = 1.232181 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 = 383 mm
al beam shear stress, Vn = VuF Wd
where:Ultimate beam shear, Vu = qu(W)(a)
Vu = 71.08152 kn
Vn = 0.296 mpa
Allow. punching shear stres sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.758288 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
Footing width, W = 1.3 mlength, L = 1.4 m
thickness, t = 300 mm
ctual wt.of footing = 12.86 knTotal weight = 186.40 kn
Area required = 1.864 sq.m
Actual Area < Required Area, NOT SAFE!
8. Required Steel Area, As a. For long direction
. of footing edge to face of support, X = 0.6 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 33.40646 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p33.4064571429 1.3 217 275 20.7 0.029292 0.0298 0.002244
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
pmin>p, use pmin
Steel area, As = pWdp = 0.00509
As = 1435.889 sq.mmN = 7.141509
Use 8 pcs --- 16 mm. dia. reinforcing bars
b. For short direction. of footing edge to face of support, Z = 1.1 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 120.92 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p120.919953846 1.4 201 275 20.7 0.114753 0.1238 0.009318
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
use p
Steel area, As = pLdp = 0.009
As = 2532.6 sq.mmN = 12.59609
Use 13 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 2438.8 sq.mmN1 = 12.12957
For center strip, use 13 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 93.8 sq.mm
N2 = 0.466522
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
outer strip center strip outer strip1.3 m
1.3 m
2/(b+1)
reinforced concrete square
column
Design of Isolated Footing
Footing No. 6Joint No. 8Load Case No. 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 80.82 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 21.46 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 149.63 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 = 8.1824 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 1.104624 sq.m
Assume footing width, W = 1 mlength, L = 1.104624 m
say W = 1 mL = 1.1 m
Actual area, A = 1.1 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 = 136.0273 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 146.2945 kpa
qa>qu, SAFE!
5. Check Punching Shear
Width of square column, c = 200 mmBar diameter, Ab = 16 mm
sume footing thickness, t = 250 mmEffective depth, d = 167 mm
punching shear stress, Vn = VuF bod
where:imate punching shear, Vu =
Vu = 131.3086 kn
Vn = 0.990401 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 = 283 mm
al beam shear stress, Vn = VuF Wd
where:Ultimate beam shear, Vu = qu(W)(a)
Vu = 38.49572 kn
Vn = 0.271 mpa
Allow. punching shear stres sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.758288 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
Footing width, W = 1 mlength, L = 1.1 m
thickness, t = 250 mm
ctual wt.of footing = 6.47 knTotal weight = 108.75 kn
Area required = 1.088 sq.m
Actual Area > Required Area, SAFE!
8. Required Steel Area, As a. For long direction
. of footing edge to face of support, X = 0.45 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 13.77276 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p13.7727613636 1 167 275 20.7 0.026508 0.0269 0.002028
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
pmin>p, use pmin
Steel area, As = pWdp = 0.00509
As = 850.03 sq.mmN = 4.227692
Use 8 pcs --- 16 mm. dia. reinforcing bars
b. For short direction. of footing edge to face of support, Z = 0.8 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 47.8816 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p47.8816 1.1 151 275 20.7 0.102473 0.1096 0.008246
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.005091 pmax = 0.0280
use p
Steel area, As = pLdp = 0.008
As = 1328.8 sq.mmN = 6.608894
Use 7 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 1265.524 sq.mmN1 = 6.294184
For center strip, use 13 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 63.27619 sq.mm
N2 = 0.314709
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
outer strip center strip outer strip1 m
1 m
2/(b+1)
reinforced concrete square
column
Design of Isolated Footing
Footing No. 4Joint No.Load Case No. 1,2
1. Support Reactions
a. Dead Load, DLFx = knFy = 101.41 knFz = knMx = knMy = knMz = kn
b. Live Load, LLFx = knFy = 26.39 knFz = knMx = knMy = knMz = kn
c. Ultimate Load (1.4 DL + 1.7LL), Pu
Pu = 186.837 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 = 10.224 kn
Area required, a = F dead load + F live load + wt. of ftg.SBC
a = 1.38024 sq.m
Assume footing width, W = 1.1 mlength, L = 1.25476 m
say W = 1.1 mL = 1.2 m
Actual area, A = 1.32 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 = 141.543 kpa
Allowable ultimate soil pressure, qa = SBC (1.4*Fy dead load + 1.7*Fy live load) Fy dead load + Fy live load
qa = 146.1948 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 = 167.773 kn
Vn = 1.26543 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 = 333 mm
Actual beam shear stress, Vn = VuF Wd
where:Ultimate beam shear, Vu = qu(W)(a)
Vu = 51.8473 kn
Vn = 0.332 mpa
Allow. punching shear stress, Vc = sqrt of F'c/6
where:F'c = 20.7 mpa
Vc = 0.75829 mpa
Vc>Vn, SAFE!
qu[A-(c+d)^2]
7. Check Footing Area
Footing width, W = 1.1 mlength, L = 1.2 m
thickness, t = 250 mm
Actual wt.of footing = 7.77 knTotal weight = 135.57 kn
Area required = 1.356 sq.m
Actual Area < Required Area, NOT SAFE!
8. Required Steel Area, As a. For long direction
Dist. of footing edge to face of support, X = 0.5 mBending moment, Mu = qu(W)(X)(X/2)
Mu = 19.46219 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) W (m) d (mm) fy (mpa) F'c (mpa) R q p19.4621875 1.1 167 275 20.7 0.03405283 0.0348 0.0026
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 = 935.033 sq.mmN = 4.65046
Use 5 pcs --- 16 mm. dia. reinforcing bars
b. For short directionDist. of footing edge to face of support, Z = 0.9 m
Bending moment, Mu = qu(L)(Z)(Z/2)Mu = 68.78999 kn-m
Mu = 0.9F'cWd^2q(1-0.59q)
Mu (kn-m) L (m) d (mm) fy (mpa) F'c (mpa) R q p68.7899863636364 1.2 151 275 20.7 0.13495135 0.1478 0.0111
pmin = 1.4 pmax = 0.75pbalfy pbal = 0.0373
pmin = 0.00509 pmax = 0.0280
use p
Steel area, As = pLdp = 0.01
As = 1812 sq.mmN = 9.01213
Use 10 pcs --- 16 mm. dia. reinforcing bars
b = L/WAs1/As =
As1 (center strip) = 1733.22 sq.mmN1 = 8.6203
For center strip, use 5 pcs --- 16 mm. dia. reinforcing bars
As1 + As2 = AsAs2 (outer strip) = 78.7826 sq.mm
N2 = 0.39183
For outer strip, use 1 pcs --- 16 mm. dia. reinforcing bars
9. Footing Detail
outer strip center strip outer strip1.1 m
1.1 m
2/(b+1)
reinforced concrete square
column