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Isolated Footing Design (IS 456-2000)
Design For Isolated Footing 1
Design For Isolated Footing 2
Design For Isolated Footing 7
Design For Isolated Footing 8
Isolated Footing 1
Footing No. Group ID Foundation Geometry
- - Length Width Thickness
1 1 1.150m 1.150m 0.230m
Footing No. Footing Reinforcement Pedestal Reinforcement
- Bottom Reinforcement(Mz) Bottom Reinforcement(M
x) Top Reinforcement(M
z) Top Reinforcement(M
x) Main Steel Trans Steel
1 Ø8 @ 140 mm c/c Ø8 @ 140 mm c/c N/A N/A N/A N/A
Footing No. Group ID Foundation Geometry
- - Length Width Thickness
2 2 1.150m 1.150m 0.230m
Footing No. Footing Reinforcement Pedestal Reinforcement
- Bottom Reinforcement(Mz) Bottom Reinforcement(M
x) Top Reinforcement(M
z) Top Reinforcement(M
x) Main Steel Trans Steel
2 Ø8 @ 140 mm c/c Ø8 @ 140 mm c/c N/A N/A N/A N/A
Footing No. Group ID Foundation Geometry
- - Length Width Thickness
7 3 1.150m 1.150m 0.230m
Footing No. Footing Reinforcement Pedestal Reinforcement
- Bottom Reinforcement(Mz) Bottom Reinforcement(M
x) Top Reinforcement(M
z) Top Reinforcement(M
x) Main Steel Trans Steel
7 Ø8 @ 140 mm c/c Ø8 @ 140 mm c/c N/A N/A N/A N/A
Footing No. Group ID Foundation Geometry
- - Length Width Thickness
8 4 1.150m 1.150m 0.230m
Footing No. Footing Reinforcement Pedestal Reinforcement
- Bottom Reinforcement(Mz) Bottom Reinforcement(M
x) Top Reinforcement(M
z) Top Reinforcement(M
x) Main Steel Trans Steel
8 Ø8 @ 140 mm c/c Ø8 @ 140 mm c/c N/A N/A N/A N/A
Page 1 of 42Isolated Footing Design
22/08/2013file:///F:/Staad%20Foundation%20Advanced/CalcXsl/footing.xml
Input Values
Footing Geomtery
Column Dimensions
Pedestal
Design Type : Calculate Dimension
Footing Thickness (Ft) : 230.000mm
Footing Length - X (Fl) : 900.000mm
Footing Width - Z (Fw) : 900.000mm
Eccentricity along X (Oxd) : 0.000mm
Eccentricity along Z (Ozd) : 0.000mm
Column Shape : Rectangular
Column Length - X (Pl) : 0.230m
Column Width - Z (Pw) : 0.230m
Include Pedestal? No
Pedestal Shape : N/A
Pedestal Height (Ph) : N/A
Pedestal Length - X (Pl) : N/A
Pedestal Width - Z (Pw) : N/A
Page 2 of 42Isolated Footing Design
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Design Parameters
Concrete and Rebar Properties
Soil Properties
Sliding and Overturning
Global Settings
Unit Weight of Concrete : 25.000kN/m3
Strength of Concrete : 20.000N/mm2
Yield Strength of Steel : 415.000N/mm2
Minimum Bar Size : Ø8
Maximum Bar Size : Ø16
Pedestal Minimum Bar Size : Ø12
Pedestal Maximum Bar Size : Ø32
Minimum Bar Spacing : 50.000mm
Maximum Bar Spacing : 200.000mm
Pedestal Clear Cover (P, CL) : 50.000mm
Footing Clear Cover (F, CL) : 75.000mm
Soil Type : Drained
Unit Weight : 18.000kN/m3
Soil Bearing Capacity : 200.000kN/m2
Soil Bearing Capacity Type: Gross Bearing Capacity
Soil Surcharge : 0.000kN/m2
Depth of Soil above Footing : 2800.000mm
Cohesion : 0.000kN/m2
Min Percentage of Slab in Contact: 0.000
Coefficient of Friction : 0.500
Factor of Safety Against Sliding : 1.500
Factor of Safety Against Overturning : 1.500
Top Reinforcement Option : Calculate only when foundation is subjected to uplift forces
Concrete Design Option : Gross Pressure
------------------------------------------------------
Design Calculations
Load Combination/s- Service Stress Level
Load Combination
Number Load Combination Title
1
2
101 1.000 x DL
102 1.000 x DL+1.000 x LL
Load Combination/s- Strength Level
Load Combination
Number Load Combination Title
1
2
201 1.500 x DL
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202 1.500 x DL+1.500 x LL
Applied Loads - Service Stress Level
LC Axial(kN)
Shear X (kN)
Shear Z (kN)
Moment X (kNm)
Moment Z(kNm)
1 86.584 -0.716 -0.716 0.000 0.000
2 18.000 -0.204 -0.204 0.000 0.000
101 86.584 -0.716 -0.716 0.000 0.000
102 104.584 -0.920 -0.920 0.000 0.000
Applied Loads - Strength Level
LC Axial
(kN)
Shear X
(kN)
Shear Z
(kN)
Moment X
(kNm)
Moment Z
(kNm)
1 86.584 -0.716 -0.716 0.000 0.000
2 18.000 -0.204 -0.204 0.000 0.000
201 129.876 -1.074 -1.074 0.000 0.000
202 156.876 -1.380 -1.380 0.000 0.000
------------------------------------------------------
Footing Size
Initial Length (Lo) = 0.900m
Initial Width (Wo) = 0.900m
Uplift force due to buoyancy = 0.000kN
Effect due to adhesion = 0.000kN
Area from initial length and width, Ao = L
o X W
o = 0.810m2
Min. area required from bearing pressure, Amin
= P / qmax
= 0.721m2
Note: Amin
is an initial estimation.
P = Critical Factored Axial Load(without self weight/buoyancy/soil). q
max = Respective Factored Bearing Capacity.
Final Footing Size
Length (L2) = 1.150 m Governing Load Case : # 1
Width (W2) = 1.150 m Governing Load Case : # 1
Depth (D2) = 0.230 m Governing Load Case : # 1
Area (A2) = 1.323 m2
Depth is governed by Ultimate Load Case
(Service check is performed with footing thickness requirements from concrete check)
Final Soil Height = 2.570 m
------------------------------------------------------
Pressures at Four Corner
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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.
Load Case
Pressure at
corner 1 (q1)
(kN/m2)
Pressure at
corner 2 (q2)
(kN/m2)
Pressure at
corner 3 (q3)
(kN/m2)
Pressure at
corner 4 (q4)
(kN/m2)
Area of
footing in
uplift (Au)
(m2)
102 130.9101 129.2403 127.5704 129.2403 0.000
102 130.9101 129.2403 127.5704 129.2403 0.000
102 130.9101 129.2403 127.5704 129.2403 0.000
102 130.9101 129.2403 127.5704 129.2403 0.000
Summary of adjusted Pressures at Four Corner
Load Case
Pressure at
corner 1 (q1)
(kN/m2)
Pressure at
corner 2 (q2)
(kN/m2)
Pressure at
corner 3 (q3)
(kN/m2)
Pressure at
corner 4 (q4)
(kN/m2)
102 130.9101 129.2403 127.5704 129.2403
102 130.9101 129.2403 127.5704 129.2403
102 130.9101 129.2403 127.5704 129.2403
102 130.9101 129.2403 127.5704 129.2403
Details of Out-of-Contact Area (If Any)
Governing load case = N/A
Plan area of footing = 1.323sq.m
Area not in contact with soil = 0.000sq.m
% of total area not in contact = 0.000%
------------------------------------------------------
Check For Stability Against Overturning And Sliding
- Factor of safety against sliding Factor of safety against overturning
Load Case
No.
Along X-
Direction
Along Z-
DirectionResultant
W.R.T. X-
Direction
W.R.T. Z-
Direction
1 106.757 106.757 75.489 533.785 533.785
2 206.747 206.747 146.192 1033.733 1033.733
101 106.757 106.757 75.489 533.785 533.785
102 92.875 92.875 65.672 464.373 464.373
Critical Load Case And The Governing Factor Of Safety For Overturning and Sliding X Direction
Critical Load Case for Sliding along X-Direction : 102
Governing Disturbing Force : -0.920kN
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Governing Restoring Force : 85.460kN
Minimum Sliding Ratio for the Critical Load Case : 92.875
Critical Load Case for Overturning w.r.t. X-Direction : 102
Governing Overturning Moment : -0.212kNm
Governing Resisting Moment : 98.277kNm
Minimum Overturning Ratio for the Critical Load Case : 464.373
Critical Load Case And The Governing Factor Of Safety For Overturning and Sliding Z Direction
Critical Load Case for Sliding along Z-Direction : 102
Governing Disturbing Force : -0.920kN
Governing Restoring Force : 85.460kN
Minimum Sliding Ratio for the Critical Load Case : 92.875
Critical Load Case for Overturning w.r.t. Z-Direction : 102
Governing Overturning Moment : 0.212kNm
Governing Resisting Moment : 98.277kNm
Minimum Overturning Ratio for the Critical Load Case : 464.373
Critical Load Case And The Governing Factor Of Safety For Sliding Along Resultant Direction
Critical Load Case for Sliding along Resultant Direction :
102
Governing Disturbing Force : 1.301kN
Governing Restoring Force : 85.460kN
Minimum Sliding Ratio for the Critical Load Case : 65.672
------------------------------------------------------
Compression Development Length Check
Development length skipped as column reinforcement is not specified in input (Column Dimnesion Task Pane)
Top Reinforcement Design Requirement
Top Reinforcement needs to be provided because of resultant negative pressure coming from net pressure calculations for bending. Please check 'Always Calculate Top Reinforcement Option' from Global Settings
Moment Calculation
Check Trial Depth against moment (w.r.t. Z Axis)
Critical Load Case = #202
Effective Depth = = 0.151m
Governing moment (Mu) = 20.647kNm
As Per IS 456 2000 ANNEX G G-1.1C
Limiting Factor1 (Kumax
) = = 0.479107
Limiting Factor2 (Rumax
) = = 2755.432917kN/m2
Limit Moment Of Resistance (Mumax
) = = 72.249306kNm
Mu <= M
umax hence, safe
Check Trial Depth against moment (w.r.t. X Axis)
Critical Load Case = #202
Page 6 of 42Isolated Footing Design
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Effective Depth = = 0.151m
Governing moment (Mu) = 20.647kNm
As Per IS 456 2000 ANNEX G G-1.1C
Limiting Factor1 (Kumax
) = = 0.479107
Limiting Factor2 (Rumax
) = = 2755.432917kN/m2
Limit Moment Of Resistance (Mumax
) = = 72.249306kNm
Mu <= M
umax hence, safe
------------------------------------------------------
Shear Calculation
Check Trial Depth for one way shear (Along X Axis)
(Shear Plane Parallel to X Axis)
Critical Load Case = # 201
DX = 0.309m
Shear Force(S) = 52.975kN
Shear Stress(Tv) = 305.066010kN/m2
Percentage Of Steel(Pt) = 0.1999
As Per IS 456 2000 Clause 40 Table 19
Shear Strength Of Concrete(Tc) = 326.161kN/m2
Tv< T
c hence, safe
Check Trial Depth for one way shear (Along Z Axis)
(Shear Plane Parallel to Z Axis)
Page 7 of 42Isolated Footing Design
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Critical Load Case = # 201
DZ = 0.309m
Shear Force(S) = 52.975kN
Shear Stress(Tv) = 305.066009kN/m2
Percentage Of Steel(Pt) = 0.1999
As Per IS 456 2000 Clause 40 Table 19
Shear Strength Of Concrete(Tc) = 326.161kN/m2
Tv< T
c hence, safe
Check Trial Depth for two way shear
Critical Load Case = #202
Shear Force(S) = 191.859kN
Shear Stress(Tv) = 833.722kN/m2
As Per IS 456 2000 Clause 31.6.3.1
Ks = = 1.000
Shear Strength(Tc)= = 1118.0340kN/m2
Ks x T
c = 1118.0340kN/m2
Tv<= K
s x T
c hence, safe
------------------------------------------------------
Reinforcement Calculation
Page 8 of 42Isolated Footing Design
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Calculation of Maximum Bar Size
Along X Axis
Bar diameter corresponding to max bar size (db) = 8mm
As Per IS 456 2000 Clause 26.2.1
Development Length(ld) = = 0.360m
Allowable Length(ldb
) = = 0.385m
ldb
>=ld hence, safe
Along Z Axis
Bar diameter corresponding to max bar size(db) = 8mm
As Per IS 456 2000 Clause 26.2.1
Development Length(ld) = = 0.360m
Allowable Length(ldb
) = = 0.385m
ldb
>=ld hence, safe
Bottom Reinforcement Design Along X Axis
For moment w.r.t. X Axis (Mz)
As Per IS 456 2000 Clause 26.5.2.1
Critical Load Case = #202
Minimum Area of Steel (Astmin
) = 317.400mm2
Calculated Area of Steel (Ast
) = 397.611mm2
Provided Area of Steel (Ast,Provided
) = 397.611mm2
Astmin
<= Ast,Provided
Steel area is accepted
Selected bar Size (db) = Ø8
Minimum spacing allowed (Smin
) = 48.000mm
Selected spacing (S) = 141.714mm
Page 9 of 42Isolated Footing Design
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Based on spacing reinforcement increment; provided reinforcement is
Based on spacing reinforcement increment; provided reinforcement is
Smin
<= S <= Smax
and selected bar size < selected maximum bar size...
The reinforcement is accepted.
Ø8 @ 140.000mm o.c.
Bottom Reinforcement Design Along Z Axis
For moment w.r.t. Z Axis (Mx)
As Per IS 456 2000 Clause 26.5.2.1
Critical Load Case = #202
Minimum Area of Steel (Astmin
) = 317.400mm2
Calculated Area of Steel (Ast
) = 397.611mm2
Provided Area of Steel (Ast,Provided
) = 397.611mm2
Astmin
<= Ast,Provided
Steel area is accepted
Selected bar Size (db) = Ø8
Minimum spacing allowed (Smin
) = = 50.000mm
Selected spacing (S) = 141.714mm
Smin
<= S <= Smax
and selected bar size < selected maximum bar size...
The reinforcement is accepted.
Ø8 @ 140.000mm o.c.
Crack Width Calculation (for Mz)
Modulus of Elasticity of Concrete(Ec) = 22360679.775kN/m2 Clause No. 6.2.3.1
Modulus of Elasticity of Steel(Es) = 200000000.000kN/m2 Annexure F
Depth of Neutral Axis(Xu) = 0.072m
Annexure G, Clause No. G-1.1.a
Effective MOI(Ieff
) = 0.000m4
Average Steel Strain at Considered Level(Ɛm
) = 20.945 X 10-5
Distance from Nearest Tension Rod (acr
) = 0.106m
Page 10 of 42Isolated Footing Design
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Crack Width (Wcr
) = 0.048mm Annexure F
From IS 456-2000 Clause No. 35.3.2
Crack Width calculated at critical tension face(bottom face) is less than 0.2 mm...Hence OK.
Crack Width Calculation (for Mx)
Modulus of Elasticity of Concrete(Ec) = 22360679.775kN/m2 Clause No. 6.2.3.1
Modulus of Elasticity of Steel(Es) = 200000000.000kN/m2 Annexure F
Depth of Neutral Axis(Xu) = 0.072m
Annexure G, Clause No. G-1.1.a
Effective MOI(Ieff
) = 0.000m4
Average Steel Strain at Considered Level(Ɛm
) = 20.945 X 10-5
Distance from Nearest Tension Rod (acr
) = 0.106m
Crack Width (Wcr
) = 0.048mm Annexure F
From IS 456-2000 Clause No. 35.3.2
Crack Width calculated at critical tension face(bottom face) is less than 0.2 mm...Hence OK.
------------------------------------------------------
Page 11 of 42Isolated Footing Design
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Isolated Footing 2
Input Values
Footing Geomtery
Column Dimensions
Pedestal
Design Type : Calculate Dimension
Footing Thickness (Ft) : 230.000mm
Footing Length - X (Fl) : 900.000mm
Footing Width - Z (Fw) : 900.000mm
Eccentricity along X (Oxd) : 0.000mm
Eccentricity along Z (Ozd) : 0.000mm
Column Shape : Rectangular
Column Length - X (Pl) : 0.230m
Column Width - Z (Pw) : 0.230m
Include Pedestal? No
Pedestal Shape : N/A
Pedestal Height (Ph) : N/A
Pedestal Length - X (Pl) : N/A
Page 12 of 42Isolated Footing Design
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