C Staad.foundation 4 CalcXsl Footing
73
Isolated Footing Design Design For Isolated Footing 1 Design For Isolated Footing 2 Design For Isolated Footing 3 Design For Isolated Footing 4 Design For Isolated Footing 5 Design For Isolated Footing 6 Design For Isolated Footing 7 Design For Isolated Footing 8 Design For Isolated Footing 9 Design For Isolated Footing 10 Design For Isolated Footing 11 Design For Isolated Footing 12 Isolated Footing 1 Input Values Concrete and Rebar Properties Concrete Covers Soil Properties Geometry Unit Weight of Concrete : 24.000 kN/m3 Strength of Concrete : 25.000 N/mm2 Yield Strength of Steel : 415.000 N/mm2 Minimum Bar Size : # 6 Maximum Bar Size : # 18 Minimum Bar Spacing : 50.00 mm Maximum Bar Spacing : 250.00 mm Pedestal Clear Cover (P, CL) : 0.00 (null) Footing Clear Cover (F, CL) : 50.00 mm Unit Weight : 20.00 kN/m3 Soil Bearing Capacity : 300.00 kN/mm2 Soil Surcharge : 0.00 kN/mm2 Depth of Soil above Footing : 900.00 mm Page 1 of 73 Isolated Footing Design 3/17/2013 file://C:\Staad.foundation 4\CalcXsl\footing.xml
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Staad Footing Design
Transcript of C Staad.foundation 4 CalcXsl Footing
Isolated Footing Design Design For Isolated Footing 1
Design For Isolated Footing 2
Design For Isolated Footing 3
Design For Isolated Footing 4
Design For Isolated Footing 5
Design For Isolated Footing 6
Design For Isolated Footing 7
Design For Isolated Footing 8
Design For Isolated Footing 9
Design For Isolated Footing 10
Design For Isolated Footing 11
Design For Isolated Footing 12
Isolated Footing 1
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Page 1 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.002 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 41.34 in Governing Load Case : # 5
Width (W2) = 41.34 in Governing Load Case : # 5
Area (A2) = 1708.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
8 0.06 0.02 0.03 0.07 -0.00
6 0.05 0.04 0.04 0.05 -0.00
6 0.05 0.04 0.04 0.05 -0.00
8 0.06 0.02 0.03 0.07 -0.00
Page 2 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
8 0.06 0.02 0.03 0.07
6 0.05 0.04 0.04 0.05
6 0.05 0.04 0.04 0.05
8 0.06 0.02 0.03 0.07
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 220.758 47.627 45.679 256.940
6 38.671 22.871 132.005 22.643
7 30.484 16.548 68.609 17.717
8 12.953 294.479 57.042 6.708
9 10.233 19033.158 57.044 5.286
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -3.016 kip
Governing Restoring Force : 30.861 kip
Minimum Sliding Ratio for the Critical Load Case : 10.233
Critical Load Case for Overturning about X-Direction :
5
Governing Overturning Moment : -28.997 kip-in
Governing Resisting Moment : 1324.571 kip-in
Minimum Overturning Ratio for the Critical Load Case :
45.679
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : 0.002 kip
Governing Restoring Force : 29.800 kip
Minimum Sliding Ratio for the Critical Load Case : 16.548
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 241.346 kip-in
Governing Resisting Moment : 1275.754 kip-
Page 3 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 33.65 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
in
Minimum Overturning Ratio for the Critical Load Case :
5.286
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along Z to design for shear, Dz = 41.32 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vux is # 5 0.02 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along X to design for shear, Dx = 0.02 in
Page 4 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vuz is # 5 0.02 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 14.76 in
Ultimate moment, 152.60 kip-in
Nominal moment capacity, Mn = 169.55 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.10 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Page 5 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Reinforcement ratio, = 0.00346
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 26.57 in
Ultimate moment, 159.56 kip-in
Nominal moment capacity, Mn = 177.29 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.04 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Page 6 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check to see if width is sufficient to accomodate bars
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00384
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Isolated Footing 2
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Page 7 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.002 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 41.34 in Governing Load Case : # 5
Width (W2) = 41.34 in Governing Load Case : # 5
Area (A2) = 1708.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
8 0.06 0.01 0.03 0.08 -0.00
5 0.05 0.05 0.05 0.05 -0.00
6 0.04 0.03 0.06 0.07 -0.00
8 0.06 0.01 0.03 0.08 -0.00
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
8 0.06 0.01 0.03 0.08
5 0.05 0.05 0.05 0.05
Page 8 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
6 0.04 0.03 0.06 0.07
8 0.06 0.01 0.03 0.08
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 844.906 40.438 37.312 2377.765
6 36.627 25.180 10.102 23.655
7 28.140 22.295 8.133 17.900
8 8.659 27.983 16.978 5.262
9 6.273 24.927 14.098 3.796
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -4.358 kip
Governing Restoring Force : 27.337 kip
Minimum Sliding Ratio for the Critical Load Case : 6.273
Critical Load Case for Overturning about X-Direction :
7
Governing Overturning Moment : -160.457 kip-in
Governing Resisting Moment : 1304.925 kip-in
Minimum Overturning Ratio for the Critical Load Case :
8.133
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -1.097 kip
Governing Restoring Force : 31.567 kip
Minimum Sliding Ratio for the Critical Load Case : 22.295
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 297.684 kip-in
Governing Resisting Moment : 1130.080 kip-in
Minimum Overturning Ratio for the Critical Load Case :
3.796
Page 9 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 45.31 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along Z to design for shear, Dz = 41.32 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vux is # 5 0.03 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along X to design for shear, Dx = 0.02 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vuz is # 5 0.03 kip
0.75 * Vc > Vuz hence, OK
Page 10 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 14.76 in
Ultimate moment, 203.63 kip-in
Nominal moment capacity, Mn = 226.25 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.10 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00346
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Page 11 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 26.57 in
Ultimate moment, 216.99 kip-in
Nominal moment capacity, Mn = 241.10 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.04 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00384
From ACI Cl.7.6.1, minimum req'd clear max (Diameter of one bar, 1.0, Min. 9.16 in
Page 12 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check to see if width is sufficient to accomodate bars
distance between bars, Cd = User Spacing) =
Isolated Footing 3
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Page 13 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.001 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 45.28 in Governing Load Case : # 5
Width (W2) = 45.28 in Governing Load Case : # 5
Area (A2) = 2049.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
9 0.02 -0.01 -0.01 0.02 495.25
5 0.02 0.02 0.02 0.02 -0.00
6 0.02 0.01 0.03 0.04 -0.00
6 0.02 0.01 0.03 0.04 -0.00
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
9 0.03 0.00 0.00 0.03
5 0.02 0.02 0.02 0.02
6 0.02 0.01 0.03 0.04
6 0.02 0.01 0.03 0.04
Page 14 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 22.06 kip, Load Case # 5
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 59.356 23.377 21.669 56.269
6 37.433 7.693 9.067 19.588
7 28.547 6.149 7.108 15.683
8 4.253 28.069 45.376 2.276
9 2.845 12.324 15.564 1.542
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -2.752 kip
Governing Restoring Force : 7.828 kip
Minimum Sliding Ratio for the Critical Load Case : 2.845
Critical Load Case for Overturning about X-Direction :
7
Governing Overturning Moment : 134.537 kip-in
Governing Resisting Moment : 956.269 kip-in
Minimum Overturning Ratio for the Critical Load Case :
7.108
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : 0.635 kip
Governing Restoring Force : 21.121 kip
Minimum Sliding Ratio for the Critical Load Case : 6.149
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 229.900 kip-in
Governing Resisting Moment : 354.397 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.542
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
Page 15 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 80.42 kip
Distance along Z to design for shear, Dz = 43.29 in
From above calculations, 0.75 * Vc = 60.31 kip
Critical load case for Vux is # 5 1.72 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 80.42 kip
Distance along X to design for shear, Dx = 1.98 in
From above calculations, 0.75 * Vc = 60.31 kip
Critical load case for Vuz is # 5 1.57 kip
0.75 * Vc > Vuz hence, OK
Page 16 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 16.73 in
Ultimate moment, 109.20 kip-in
Nominal moment capacity, Mn = 121.33 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.20 sq.in
Available development length for bars, DL = 14.76 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00316
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
10.15 in
Page 17 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 28.54 in
Ultimate moment, 117.52 kip-in
Nominal moment capacity, Mn = 130.57 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.14 sq.in
Available development length for bars, DL = 14.76 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00420
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
8.12 in
Page 18 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Isolated Footing 4
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Page 19 of 73Isolated Footing Design
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Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Min. area required from bearing pressure, Amin = P / qmax = 0.003 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 41.34 in Governing Load Case : # 5
Width (W2) = 41.34 in Governing Load Case : # 5
Area (A2) = 1708.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
7 0.06 0.06 0.06 0.07 -0.00
7 0.06 0.06 0.06 0.07 -0.00
8 -0.03 -0.07 0.17 0.22 325.37
8 -0.03 -0.07 0.17 0.22 325.37
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
7 0.06 0.06 0.06 0.07
7 0.06 0.06 0.06 0.07
8 0.00 0.00 0.19 0.25
8 0.00 0.00 0.19 0.25
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 1.820 14.804 1.838 13.859
6 2.795 3.220 7.678 71.948
Page 20 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 35.01 kip, Load Case # 5
7 3.596 2.462 48.115 103.979
8 2.630 31.618 1.857 10.807
9 3.287 17.656 1.874 11.230
Critical Load Case for Sliding along X-Direction : 5
Governing Disturbing Force : -28.089 kip
Governing Restoring Force : 51.114 kip
Minimum Sliding Ratio for the Critical Load Case : 1.820
Critical Load Case for Overturning about X-Direction :
5
Governing Overturning Moment : 1149.812 kip-in
Governing Resisting Moment : 2112.967 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.838
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -2.853 kip
Governing Restoring Force : 51.848 kip
Minimum Sliding Ratio for the Critical Load Case : 2.462
Critical Load Case for Overturning about Z-Direction :
8
Governing Overturning Moment : 243.471 kip-in
Governing Resisting Moment : 2631.092 kip-in
Minimum Overturning Ratio for the Critical Load Case :
10.807
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Page 21 of 73Isolated Footing Design
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Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along Z to design for shear, Dz = 41.32 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vux is # 5 0.08 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along X to design for shear, Dx = 0.02 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vuz is # 5 0.05 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
Page 22 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 14.76 in
Ultimate moment, 297.13 kip-in
Nominal moment capacity, Mn = 330.14 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.10 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00346
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
Page 23 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 26.57 in
Ultimate moment, 653.25 kip-in
Nominal moment capacity, Mn = 725.83 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.04 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00384
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Isolated Footing 5
Input Values
Page 24 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.003 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Page 25 of 73Isolated Footing Design
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Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Length (L2) = 49.21 in Governing Load Case : # 5
Width (W2) = 49.21 in Governing Load Case : # 5
Area (A2) = 2421.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
5 0.18 -0.06 -0.06 0.19 581.25
9 0.03 0.03 0.04 0.04 0.00
9 0.03 0.03 0.04 0.04 0.00
5 0.18 -0.06 -0.06 0.19 581.25
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
5 0.24 0.00 0.00 0.24
9 0.03 0.03 0.04 0.04
9 0.03 0.03 0.04 0.04
5 0.24 0.00 0.00 0.24
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 3.438 105.421 78.757 1.517
6 4.485 25.078 9.288 2.101
7 5.359 19.993 6.693 2.814
8 11.123 84.670 28.028 4.096
9 51.112 129.719 23.855 132.927
Page 26 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = -58.24 kip, Load Case # 5
Critical Load Case for Sliding along X-Direction : 5
Governing Disturbing Force : 21.634 kip
Governing Restoring Force : 74.384 kip
Minimum Sliding Ratio for the Critical Load Case : 3.438
Critical Load Case for Overturning about X-Direction :
7
Governing Overturning Moment : -318.094 kip-in
Governing Resisting Moment : 2129.055 kip-in
Minimum Overturning Ratio for the Critical Load Case :
6.693
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -0.313 kip
Governing Restoring Force : 43.262 kip
Minimum Sliding Ratio for the Critical Load Case : 19.993
Critical Load Case for Overturning about Z-Direction :
5
Governing Overturning Moment : -2413.650 kip-in
Governing Resisting Moment : 3660.649 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.517
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
Page 27 of 73Isolated Footing Design
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Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
From ACI Cl.11.3.1.1, Vc = 87.41 kip
Distance along Z to design for shear, Dz = 45.26 in
From above calculations, 0.75 * Vc = 65.56 kip
Critical load case for Vux is # 5 11.51 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 87.41 kip
Distance along X to design for shear, Dx = 3.95 in
From above calculations, 0.75 * Vc = 65.56 kip
Critical load case for Vuz is # 5 45.94 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Page 28 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 18.70 in
Ultimate moment, 1594.46 kip-in
Nominal moment capacity, Mn = 1771.62 kip-in
Required = 0.00283
Since OK
Area of Steel Required, As = 2.05 sq.in
Available development length for bars, DL = 16.73 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00349
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
8.91 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Page 29 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 30.51 in
Ultimate moment, 509.74 kip-in
Nominal moment capacity, Mn = 566.38 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.24 sq.in
Available development length for bars, DL = 16.73 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00387
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
8.91 in
Isolated Footing 6
Input Values
Concrete and Rebar Properties
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Page 30 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.004 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 53.15 in Governing Load Case : # 9
Width (W2) = 53.15 in Governing Load Case : # 9
Area (A2) = 2824.88 in2
Page 31 of 73Isolated Footing Design
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Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
6 0.09 -0.07 0.02 0.17 501.70
5 0.05 -0.13 0.07 0.25 659.89
5 0.05 -0.13 0.07 0.25 659.89
5 0.05 -0.13 0.07 0.25 659.89
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
6 0.08 0.00 0.00 0.21
5 0.00 0.00 0.01 0.40
5 0.00 0.00 0.01 0.40
5 0.00 0.00 0.01 0.40
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 13.717 9.318 1.798 2.031
6 99.532 4.773 3.502 2.007
7 15.949 2.771 7.619 2.107
8 9.633 339.089 2.161 1.612
9 4.308 13.476 2.708 1.503
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -8.727 kip
Governing Restoring Force : 37.592 kip
Page 32 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = -136.47 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Minimum Sliding Ratio for the Critical Load Case : 4.308
Critical Load Case for Overturning about X-Direction :
5
Governing Overturning Moment : 2490.895 kip-in
Governing Resisting Moment : 4479.174 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.798
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -2.790 kip
Governing Restoring Force : 49.787 kip
Minimum Sliding Ratio for the Critical Load Case : 2.771
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 1329.668 kip-in
Governing Resisting Moment : 1997.987 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.503
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
Page 33 of 73Isolated Footing Design
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Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
From ACI Cl.11.3.1.1, Vc = 94.40 kip
Distance along Z to design for shear, Dz = 47.23 in
From above calculations, 0.75 * Vc = 70.80 kip
Critical load case for Vux is # 5 56.36 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 94.40 kip
Distance along X to design for shear, Dx = 5.92 in
From above calculations, 0.75 * Vc = 70.80 kip
Critical load case for Vuz is # 5 49.34 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 20.67 in
Ultimate moment, 1512.88 kip-in
Nominal moment capacity, Mn = 1680.98 kip-in
Page 34 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Required = 0.00248
Since OK
Area of Steel Required, As = 1.94 sq.in
Available development length for bars, DL = 18.70 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00323
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.69 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Page 35 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 32.48 in
Ultimate moment, 1685.67 kip-in
Nominal moment capacity, Mn = 1872.97 kip-in
Required = 0.00308
Since OK
Area of Steel Required, As = 2.29 sq.in
Available development length for bars, DL = 18.70 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00358
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.69 in
Isolated Footing 7
Input Values
Concrete and Rebar Properties
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Page 36 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.003 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 74.80 in Governing Load Case : # 5
Width (W2) = 74.80 in Governing Load Case : # 5
Area (A2) = 5595.51 in2
Page 37 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
5 0.01 0.01 0.04 0.04 0.00
5 0.01 0.01 0.04 0.04 0.00
6 -0.01 -0.01 0.05 0.05 1038.53
6 -0.01 -0.01 0.05 0.05 1038.53
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
5 0.01 0.01 0.04 0.04
5 0.01 0.01 0.04 0.04
6 0.00 0.00 0.06 0.06
6 0.00 0.00 0.06 0.06
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 2.208 23.642 5.154 156.915
6 2.402 2.170 1.912 188.181
7 3.010 1.532 1.500 101.020
8 2.686 6.041 2.807 58.234
9 3.363 4.853 2.473 46.919
Critical Load Case for Sliding along X-Direction : 5
Governing Disturbing Force : -33.794 kip
Governing Restoring Force : 74.628 kip
Minimum Sliding Ratio for the Critical Load Case : 2.208
Critical Load Case for Overturning about X-Direction :
7
Page 38 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 110.33 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Governing Overturning Moment : -2002.888 kip-in
Governing Resisting Moment : 3005.079 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.500
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -11.511 kip
Governing Restoring Force : 40.173 kip
Minimum Sliding Ratio for the Critical Load Case : 1.532
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 89.071 kip-in
Governing Resisting Moment : 4179.113 kip-in
Minimum Overturning Ratio for the Critical Load Case :
46.919
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 132.86 kip
Page 39 of 73Isolated Footing Design
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Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Distance along Z to design for shear, Dz = 58.06 in
From above calculations, 0.75 * Vc = 99.65 kip
Critical load case for Vux is # 5 43.36 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 132.86 kip
Distance along X to design for shear, Dx = 16.75 in
From above calculations, 0.75 * Vc = 99.65 kip
Critical load case for Vuz is # 5 28.76 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 31.50 in
Ultimate moment, 850.72 kip-in
Nominal moment capacity, Mn = 945.25 kip-in
Page 40 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Required = 0.00180
Since OK
Area of Steel Required, As = 1.99 sq.in
Available development length for bars, DL = 29.53 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 8
Total reinforcement area, As_total = Nbar * (Area of one bar) = 3.52 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00306
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
10.02 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 43.31 in
Page 41 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Ultimate moment, 1251.84 kip-in
Nominal moment capacity, Mn = 1390.93 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.88 sq.in
Available development length for bars, DL = 29.53 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 8
Total reinforcement area, As_total = Nbar * (Area of one bar) = 3.52 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00339
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
10.02 in
Isolated Footing 8
Input Values
Concrete and Rebar Properties
Concrete Covers
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Page 42 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.004 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 46.26 in Governing Load Case : # 5
Width (W2) = 46.26 in Governing Load Case : # 5
Area (A2) = 2139.97 in2
Page 43 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
5 0.23 -0.08 -0.07 0.24 513.59
9 0.04 0.03 0.04 0.05 -0.00
9 0.04 0.03 0.04 0.05 -0.00
5 0.23 -0.08 -0.07 0.24 513.59
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
5 0.31 0.00 0.00 0.32
9 0.04 0.03 0.04 0.05
9 0.04 0.03 0.04 0.05
5 0.31 0.00 0.00 0.32
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 3.049 93.778 69.397 1.513
6 4.331 87.587 12.551 1.997
7 6.124 32.774 6.845 2.789
8 8.301 17282.154 54.665 3.655
9 111.909 93.792 23.476 217.227
Critical Load Case for Sliding along X-Direction : 5
Governing Disturbing Force : 27.841 kip
Governing Restoring Force : 84.891 kip
Minimum Sliding Ratio for the Critical Load Case : 3.049
Critical Load Case for Overturning about X-Direction :
7
Page 44 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = -43.87 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Governing Overturning Moment : -267.378 kip-in
Governing Resisting Moment : 1830.075 kip-in
Minimum Overturning Ratio for the Critical Load Case :
6.845
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -0.456 kip
Governing Restoring Force : 39.561 kip
Minimum Sliding Ratio for the Critical Load Case : 32.774
Critical Load Case for Overturning about Z-Direction :
5
Governing Overturning Moment : -2594.835 kip-in
Governing Resisting Moment : 3927.062 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.513
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 82.16 kip
Page 45 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Distance along Z to design for shear, Dz = 43.78 in
From above calculations, 0.75 * Vc = 61.62 kip
Critical load case for Vux is # 5 8.94 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 82.16 kip
Distance along X to design for shear, Dx = 2.48 in
From above calculations, 0.75 * Vc = 61.62 kip
Critical load case for Vuz is # 5 35.56 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 17.22 in
Ultimate moment, 1648.37 kip-in
Nominal moment capacity, Mn = 1831.52 kip-in
Page 46 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Required = 0.00312
Since OK
Area of Steel Required, As = 2.13 sq.in
Available development length for bars, DL = 15.26 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00309
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
10.39 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 29.04 in
Page 47 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Ultimate moment, 535.58 kip-in
Nominal moment capacity, Mn = 595.09 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.17 sq.in
Available development length for bars, DL = 15.26 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00411
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
8.31 in
Isolated Footing 9
Input Values
Concrete and Rebar Properties
Concrete Covers
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Page 48 of 73Isolated Footing Design
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Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.004 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 68.90 in Governing Load Case : # 7
Width (W2) = 68.90 in Governing Load Case : # 7
Area (A2) = 4746.88 in2
Page 49 of 73Isolated Footing Design
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If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
5 0.05 -0.05 0.04 0.14 736.72
5 0.05 -0.05 0.04 0.14 736.72
5 0.05 -0.05 0.04 0.14 736.72
6 0.02 -0.06 0.04 0.13 1070.90
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
5 0.04 0.00 0.03 0.16
5 0.04 0.00 0.03 0.16
5 0.04 0.00 0.03 0.16
6 0.00 0.00 0.02 0.19
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 16.964 13.858 2.773 2.558
6 71.260 2.671 1.806 2.250
7 13.583 1.787 1.526 2.247
8 12.428 6.100 2.477 2.063
9 5.372 4.475 2.416 1.956
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -8.160 kip
Governing Restoring Force : 43.836 kip
Minimum Sliding Ratio for the Critical Load Case : 5.372
Critical Load Case for Overturning about X-Direction :
7
Page 50 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 98.46 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Governing Overturning Moment : -2087.905 kip-in
Governing Resisting Moment : 3185.228 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.526
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : -9.797 kip
Governing Restoring Force : 46.231 kip
Minimum Sliding Ratio for the Critical Load Case : 1.787
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 1544.292 kip-in
Governing Resisting Moment : 3020.214 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.956
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 122.37 kip
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Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Distance along Z to design for shear, Dz = 55.10 in
From above calculations, 0.75 * Vc = 91.78 kip
Critical load case for Vux is # 5 74.53 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 122.37 kip
Distance along X to design for shear, Dx = 13.80 in
From above calculations, 0.75 * Vc = 91.78 kip
Critical load case for Vuz is # 5 78.43 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 28.54 in
Ultimate moment, 2164.66 kip-in
Nominal moment capacity, Mn = 2405.17 kip-in
Page 52 of 73Isolated Footing Design
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Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Required = 0.00274
Since OK
Area of Steel Required, As = 2.78 sq.in
Available development length for bars, DL = 26.57 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 8
Total reinforcement area, As_total = Nbar * (Area of one bar) = 3.52 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00332
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.17 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 40.35 in
Page 53 of 73Isolated Footing Design
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Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Ultimate moment, 2071.13 kip-in
Nominal moment capacity, Mn = 2301.25 kip-in
Required = 0.00291
Since OK
Area of Steel Required, As = 2.81 sq.in
Available development length for bars, DL = 26.57 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 8
Total reinforcement area, As_total = Nbar * (Area of one bar) = 3.52 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00368
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.17 in
Isolated Footing 10
Input Values
Concrete and Rebar Properties
Concrete Covers
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Page 54 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.001 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 56.10 in Governing Load Case : # 9
Width (W2) = 56.10 in Governing Load Case : # 9
Area (A2) = 3147.48 in2
Page 55 of 73Isolated Footing Design
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If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
5 0.02 0.02 0.02 0.02 0.00
5 0.02 0.02 0.02 0.02 0.00
5 0.02 0.02 0.02 0.02 0.00
9 0.01 -0.01 0.00 0.01 795.68
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
5 0.02 0.02 0.02 0.02
5 0.02 0.02 0.02 0.02
5 0.02 0.02 0.02 0.02
9 0.00 0.00 0.00 0.02
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 655.478 1029.548 308.514 240.887
6 21.692 4.945 6.615 723.421
7 12.651 2.885 3.916 235.175
8 6.723 4.903 6.108 3.823
9 2.686 1.934 2.459 1.513
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -1.889 kip
Governing Restoring Force : 5.075 kip
Minimum Sliding Ratio for the Critical Load Case : 2.686
Critical Load Case for Overturning about X-Direction :
9
Page 56 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 40.80 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Governing Overturning Moment : 115.785 kip-in
Governing Resisting Moment : 284.694 kip-in
Minimum Overturning Ratio for the Critical Load Case :
2.459
Critical Load Case for Sliding along Z-Direction : 9
Governing Disturbing Force : 2.624 kip
Governing Restoring Force : 5.075 kip
Minimum Sliding Ratio for the Critical Load Case : 1.934
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 188.154 kip-in
Governing Resisting Moment : 284.694 kip-in
Minimum Overturning Ratio for the Critical Load Case :
1.513
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 99.65 kip
Page 57 of 73Isolated Footing Design
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Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Distance along Z to design for shear, Dz = 48.70 in
From above calculations, 0.75 * Vc = 74.73 kip
Critical load case for Vux is # 5 7.01 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 99.65 kip
Distance along X to design for shear, Dx = 7.40 in
From above calculations, 0.75 * Vc = 74.73 kip
Critical load case for Vuz is # 5 7.03 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 22.15 in
Ultimate moment, 232.48 kip-in
Nominal moment capacity, Mn = 258.32 kip-in
Page 58 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Required = 0.00180
Since OK
Area of Steel Required, As = 1.49 sq.in
Available development length for bars, DL = 20.18 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 6
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.64 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00306
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
10.28 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 33.96 in
Page 59 of 73Isolated Footing Design
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Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Program has detected one or more load cases to be in pure uplift, so footing needs to be designed for these cases with Top reinforcement.
Bending moment for uplift cases will be calculated based solely on selfweight, soil depth and surcharge loading.
As the footing size has already been determined based on all servicebility load cases, and design moment calculation is based on selfweight, soil depth and surcharge only, top reinforcement value for all pure uplift load cases will be the same.
Design for top reinforcement about Z axis
First load case to be in pure uplift # 9
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required
The strength values of steel and concrete used in the formulae are in ksi
Ultimate moment, 231.91 kip-in
Nominal moment capacity, Mn = 257.68 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.41 sq.in
Available development length for bars, DL = 20.18 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 7
Total reinforcement area, As_total = Nbar * (Area of one bar) = 3.08 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00396
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
8.57 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
Page 60 of 73Isolated Footing Design
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Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Design for top reinforcement about X axis
First load case to be in pure uplift # 9
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about A axis is performed at the face of the column at a distance, Dx = 22.15 in
Ultimate moment, 57.46 kip-in
Nominal moment capacity, Mn = 63.85 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.41 sq.in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about A axis is performed at the face of the column at a distance, Dx = 22.15 in
Ultimate moment, 57.46 kip-in
Nominal moment capacity, Mn = 63.85 kip-in
Required = 0.00180
Page 61 of 73Isolated Footing Design
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Find suitable bar arrangement between minimum and maximum rebar sizes
Since OK
Area of Steel Required, As = 1.49 sq.in
Isolated Footing 11
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Page 62 of 73Isolated Footing Design
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Footing Design Calculations
Footing Size
Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Min. area required from bearing pressure, Amin = P / qmax = 0.002 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 41.34 in Governing Load Case : # 5
Width (W2) = 41.34 in Governing Load Case : # 5
Area (A2) = 1708.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
8 0.07 0.02 0.04 0.08 -0.00
5 0.06 0.05 0.06 0.06 -0.00
5 0.06 0.05 0.06 0.06 -0.00
8 0.07 0.02 0.04 0.08 -0.00
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
8 0.07 0.02 0.04 0.08
5 0.06 0.05 0.06 0.06
5 0.06 0.05 0.06 0.06
8 0.07 0.02 0.04 0.08
Page 63 of 73Isolated Footing Design
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Check for stability against overturning and sliding:-
Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 82.449 114.165 91.639 88.424
6 11.939 6.706 6.863 6.729
7 7.260 4.108 4.230 4.072
8 13.689 23.340 23.757 6.730
9 9.497 16.726 17.311 4.649
Critical Load Case for Sliding along X-Direction : 7
Governing Disturbing Force : -2.979 kip
Governing Restoring Force : 21.630 kip
Minimum Sliding Ratio for the Critical Load Case : 7.260
Critical Load Case for Overturning about X-Direction :
7
Governing Overturning Moment : 211.398 kip-in
Governing Resisting Moment : 894.161 kip-in
Minimum Overturning Ratio for the Critical Load Case :
4.230
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : 1.884 kip
Governing Restoring Force : 21.630 kip
Minimum Sliding Ratio for the Critical Load Case : 4.108
Critical Load Case for Overturning about Z-Direction :
7
Governing Overturning Moment : 219.563 kip-in
Governing Resisting Moment : 894.161 kip-in
Minimum Overturning Ratio for the Critical Load Case :
4.072
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
Page 64 of 73Isolated Footing Design
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Punchng Shear Force, Pu = 55.04 kip, Load Case # 5
Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along Z to design for shear, Dz = 41.32 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vux is # 5 0.04 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along X to design for shear, Dx = 0.02 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vuz is # 5 0.04 kip
0.75 * Vc > Vuz hence, OK
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Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 14.76 in
Ultimate moment, 253.94 kip-in
Nominal moment capacity, Mn = 282.16 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.10 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00346
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Page 66 of 73Isolated Footing Design
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Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 26.57 in
Ultimate moment, 253.72 kip-in
Nominal moment capacity, Mn = 281.91 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.04 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00384
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
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Isolated Footing 12
Input Values
Concrete and Rebar Properties
Concrete Covers
Soil Properties
Geometry
Initial Footing Dimensions
Pedestal
Footing Design Calculations
Footing Size
Unit Weight of Concrete : 24.000 kN/m3
Strength of Concrete : 25.000 N/mm2
Yield Strength of Steel : 415.000 N/mm2
Minimum Bar Size : # 6
Maximum Bar Size : # 18
Minimum Bar Spacing : 50.00 mm
Maximum Bar Spacing : 250.00 mm
Pedestal Clear Cover (P, CL) : 0.00 (null)
Footing Clear Cover (F, CL) : 50.00 mm
Unit Weight : 20.00 kN/m3
Soil Bearing Capacity : 300.00 kN/mm2
Soil Surcharge : 0.00 kN/mm2
Depth of Soil above Footing : 900.00 mm
Thickness (Ft) : 450.00 mm
Length - X (Fl) : 300.00 mm
Width - Z (Fw) : 300.00 mm
Eccentricity along X (Oxd) : 0.00 in
Eccentricity along Z (Ozd) : 0.00 in
Include Pedestal? No
Initial Length (Lo) = 11.81 in
Initial Width (Wo) = 11.81 in
Page 68 of 73Isolated Footing Design
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Final dimensions for design.
Calculated pressures at 4 corners.
If Au is zero, there is no uplift and no pressure adjustment is necessary. Otherwise, to account for uplift, areas of negative
pressure will be set to zero and the pressure will be redistributed to remaining corners.
Summary of adjusted pressures at 4 corners.
Adjust footing size if necessary.
Check for stability against overturning and sliding:-
Min. area required from bearing pressure, Amin = P / qmax = 0.003 in2
Area from initial length and width, Ao = Lo * Wo = 139.50 in2
Length (L2) = 41.34 in Governing Load Case : # 5
Width (W2) = 41.34 in Governing Load Case : # 5
Area (A2) = 1708.88 in2
Load CasePressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
Area of footing in uplift (Au)
(in2)
8 0.09 0.04 0.04 0.09 -0.00
5 0.08 0.07 0.07 0.08 -0.00
5 0.08 0.07 0.07 0.08 -0.00
8 0.09 0.04 0.04 0.09 -0.00
Load Case
Pressure at corner 1 (q1)
(kip/in^2)
Pressure at corner 2 (q2)
(kip/in^2)
Pressure at corner 3 (q3)
(kip/in^2)
Pressure at corner 4 (q4)
(kip/in^2)
8 0.09 0.04 0.04 0.09
5 0.08 0.07 0.07 0.08
5 0.08 0.07 0.07 0.08
8 0.09 0.04 0.04 0.09
Factor of safety against slidingFactor of safety against
overturning
Load Case No.
Along X-Direction
Along Z-Direction
About X-Direction
About Z-Direction
5 75.694 303.407 1516.189 64.090
6 26.525 46.972 70.559 11.386
Page 69 of 73Isolated Footing Design
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Critical load case and the governing factor of safety for overturning and sliding
Critical load case and the governing factor of safety for overturning and sliding
Check Trial Depth against Punching Shear strength, Vc
Effective depth, deff, increased until 0.75*Vc Punching Shear Force
Punchng Shear Force, Pu = 70.54 kip, Load Case # 5
7 14.317 25.328 43.887 6.397
8 15.163 89.551 2154.369 7.952
9 9.864 53.243 5638.043 5.245
Critical Load Case for Sliding along X-Direction : 9
Governing Disturbing Force : -3.927 kip
Governing Restoring Force : 38.736 kip
Minimum Sliding Ratio for the Critical Load Case : 9.864
Critical Load Case for Overturning about X-Direction :
7
Governing Overturning Moment : -24.942 kip-in
Governing Resisting Moment : 1094.655 kip-in
Minimum Overturning Ratio for the Critical Load Case :
43.887
Critical Load Case for Sliding along Z-Direction : 7
Governing Disturbing Force : 0.728 kip
Governing Restoring Force : 26.480 kip
Minimum Sliding Ratio for the Critical Load Case : 25.328
Critical Load Case for Overturning about Z-Direction :
9
Governing Overturning Moment : 305.295 kip-in
Governing Resisting Moment : 1601.300 kip-in
Minimum Overturning Ratio for the Critical Load Case :
5.245
Calculated Effective Depth, deff = D - Ccover - 1.0 = 14.75 in
For rectangular column, = Bcol / Dcol = 1.00
From ACI Cl.11.12.2.1, for column = 106.24 in
Equation 11-33, Vc1 = 566.07 kip
Equation 11-34, Vc2 = 712.58 kip
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Check Trial Depth against One-Way Shear strength, Vc
Shear along the Z-Z axis.
Check that 0.75 * Vc > Vux where Vux is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the X axis.
Shear along the X-X axis.
Check that 0.75 * Vc > Vuz where Vuz is the shear force for the critical load cases at a distance deff from the face of the
column caused by bending about the Z axis.
Design for Flexure about Z axis
Calculate the flexural reinforcement along the X direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
Equation 11-35, Vc3 = 377.38 kip
Punching shear strength, Vc = 0.75 * minimum of (Vc1, Vc2, Vc3) = 283.03 kip
0.75 * Vc > Vu hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along Z to design for shear, Dz = 41.32 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vux is # 5 0.05 kip
0.75 * Vc > Vux hence, OK
From ACI Cl.11.3.1.1, Vc = 73.42 kip
Distance along X to design for shear, Dx = 0.02 in
From above calculations, 0.75 * Vc = 55.07 kip
Critical load case for Vuz is # 5 0.05 kip
0.75 * Vc > Vuz hence, OK
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl. 7.12.2, = 0.00180
Page 71 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
Design for Flexure about X axis
Calculate the flexural reinforcement along the Z direction of the footing. Find the area of steel required, A, as per Section 3.8 of Reinforced Concrete Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 5
The strength values of steel and concrete used in the formulae are in ksi
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about Z axis is performed at the face of the column at a distance, Dx = 14.76 in
Ultimate moment, 328.63 kip-in
Nominal moment capacity, Mn = 365.15 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.10 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 15.37 in
Reinforcement ratio, = 0.00346
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Factor from ACI Cl.10.2.7.3 for Fc' 4 ksi, 0.85
From ACI Cl. 10.3.2, = 0.02573
Page 72 of 73Isolated Footing Design
3/17/2013file://C:\Staad.foundation 4\CalcXsl\footing.xml
Calculate reinforcement ratio for critical load case
Find suitable bar arrangement between minimum and maximum rebar sizes
Because the number of bars is rounded up, make sure new reinforcement ratio < max
Check to see if width is sufficient to accomodate bars
From ACI Cl. 10.3.3, = 0.01929
From ACI Cl.7.12.2, = 0.00180
From Ref. 1, Eq. 3.8.4a, constant m = 19.53
Design for flexure about X axis is performed at the face of the column at a distance, Dz = 26.57 in
Ultimate moment, 317.21 kip-in
Nominal moment capacity, Mn = 352.45 kip-in
Required = 0.00180
Since OK
Area of Steel Required, As = 1.04 sq.in
Available development length for bars, DL = 12.80 in
Try bar size # 6 Area of one bar = 0.44 sq.in
Number of bars required, Nbar = 5
Total reinforcement area, As_total = Nbar * (Area of one bar) = 2.20 sq.in
deff = D - Ccover - 0.5 * (dia. of one bar) = 13.87 in
Reinforcement ratio, = 0.00384
From ACI Cl.7.6.1, minimum req'd clear distance between bars, Cd =
max (Diameter of one bar, 1.0, Min. User Spacing) =
9.16 in
Print Calculation Sheet
Page 73 of 73Isolated Footing Design
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