P01 Footing Design

ANNEXURE -A
(I) ISOLATED FOOTING DESIGN
Input Values
Footing Geometry
Footing Thickness (Ft) = 305.000 mm
Footing Length - X (Fl) = 1000.000 mm
Footing Width - Z (Fw) = 1000.000 mm
Eccentricity along X (Oxd) = 0.000 mm
Eccentricity along Z (Ozd) = 0.000 mm
Column Dimensions
Column Shape =Rectangular
Column Length - X (Pl) =0.400 m
Column Width - Z (Pw) =0.300 m
Design Parameters
Concrete and Rebar Properties
Unit Weight of Concrete = 25.000 kN/m3
Strength of Concrete = 25.000 N/mm2
Yield Strength of Steel = 415.000 N/mm2
Minimum Bar Size = Ø6
Maximum Bar Size = Ø32
Minimum Bar Spacing = 50.000 mm
Maximum Bar Spacing = 500.000 mm
Pedestal Clear Cover (P, CL) = 50.000 mm
Footing Clear Cover (F, CL) = 50.000 mm
Soil Properties
Soil Type = Drained
85
Unit Weight = 21.000 kN/m3
Soil Bearing Capacity = 290.000 kN/m2
Soil Surcharge = 30.000 kN/m2
Depth of Soil above Footing = 1500.000 mm
Cohesion = 0.000 kN/m2
Sliding and Overturning

Coefficient of Friction = 0.500
Factor of Safety Against Sliding = 1.500
Factor of Safety Against Overturning = 1.500
Load Combination/s- Service Stress Level

Load Combination Number Load Combination Title
3 Combination Load Case 3
Load Combination/s- Strength Level
Load Combination Number Load Combination Title
3 Combination Load Case 3
Applied Loads - Service Stress Level
LC Axial Shear X Shear Z Moment X Moment Z
(kN) (kN) (kN) (kNm) (kNm)
3 871.325 21.940 52.387 16.497 -5.836
Applied Loa ds - Strength Level
LC Axial Shear X Shear Z Moment X Moment Z
(kN) (kN) (kN) (kNm) (kNm)
3 871.325 21.940 52.387 16.497 -5.836
Design Calculations
Footing Size
Initial Length (Lo) = 1.000 m
Initial Width (Wo) = 1.000 m
Uplift force due to buoyancy = 77.338 kN
Effect due to adhesion = 0.000 kN
86
Area from initial length and width, Ao = Lo X Wo = 1.000 m2
Min. area required from bearing pressure, Amin = P / qmax = 3.852 m2
Note: Amin is an initial estimation.

P = Critical Factored Axial Load(without self weight/buoyancy/soil).
qmax = Respective Factored Bearing Capacity.
Final Footing Size

Length (L2) = 2.150 m
Width (W2) = 2.150 m
Depth (D2) = 0.507 m
Area (A2) = 4.623 m2
Pressures at Four Corner
Load Pressure at Pressure at Pressure at Pressure at Area of

Case corner 1 (q1) corner 2 (q2) corner 3 (q3) corner 4 (q4) footing in
uplift (Au)
(kN/m2) (kN/m2) (kN/m2) (kN/m2)
(m2)
3 221.1150 237.3475 279.4278 263.1952 0.000
3 221.1150 237.3475 279.4278 263.1952 0.000
3 208.1306 228.5815 280.5079 260.0570 0.000
3 221.1150 237.3475 279.4278 263.1952 0.000
87
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 Four Corner
Load Case Pressure at Pressure at Pressure at Pressure at

corner 1 (q1) corner 2 (q2) corner 3 (q3) corner 4 (q4)
(kN/m2) (kN/m2) (kN/m2) (kN/m2)

3 221.1150 237.3475 279.4278 263.1952
3 221.1150 237.3475 279.4278 263.1952
3 208.1306 228.5815 280.5079 260.0570
3 221.1150 237.3475 279.4278 263.1952
Details of Out-of-Contact Area
(If Any)
Governing load case = N/A
Plan area of footing = 4.623 sq.m
Area not in contact with soil = 0.000 sq.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 Along X- Along Z- About X- About Z-

No. Direction Direction Direction Direction
3 25.738 10.779 28.231 71.680
Critical Load Case And The Governing Factor Of Safety For Overturning and Sliding X
Direction
Critical Load Case for Sliding along X-Direction = 3

Governing Disturbing Force = 21.940 kN
Governing Restoring Force =5 64.683 kN
88
Minimum Sliding Ratio for the Critical Load Case = 25.738
Critical Load Case for Overturning about X-Direction = 3
Governing Overturning Moment = 43.005 kNm
Governing Resisting Moment = 1214.046 kNm
Minimum Overturning Ratio for the Critical Load Case =28.231
Critical Load Case And The Governing Factor Of Safety For Overturning and Sliding Z
Direction
Critical Load Case for Sliding along Z-Direction =3

Governing Disturbing Force =52.388 kN
Governing Restoring Force =564.683 kN
Minimum Sliding Ratio for the Critical Load Case =10.779
Critical Load Case for Overturning about Z-Direction =3
Governing Overturning Moment =-16.937 kNm
Governing Resisting Moment =1214.046 kNm
Minimum Overturning Ratio for the Critical Load Case =71.680
Moment Calculation
Check Trial Depth against moment (w.r.t. X Axis)
Effective Depth = = 0.453 m
Governing moment (Mu) = 241.764 kNm

As Per IS 456 2000 ANNEX G G-1.1C
= 0.479107
Limiting Factor1 (Kumax) =
Limiting Factor2 (Rumax) = = 3444.291146 kN/m2
= 1519.591251 kNm Limit Moment Of Resistance (Mumax) =

Mu <= Mumax
hence, safe
Check Trial Depth against moment (w.r.t. Z Axis)

Effective Depth = = 0.453 m
Governing moment (Mu) = 207.221 kNm
89
As Per IS 456 2000 ANNEX G G-1.1C
Limiting Factor1 (Kumax) = = 0.479107
Limiting Factor2 (Rumax) = = 3444.29114 kN/m2 Limit Moment Of Resistance (Mumax) =

= 1519.591251 kNm
Mu <= Mumax hence, safe

Shear Calculation
Check Trial Depth for one way shear (Along X Axis)

(Shear Plane Parallel to X Axis)
DX = 0.453 m
Shear Force(S) = 268.499 kN
Shear Stress(Tv) = 275.680035 kN/m2
Percentage Of Steel(Pt) = 0.1343
As Per IS 456 2000 Clause 40 Table 19
Shear Strength Of Concrete(Tc) = 276.571 kN/m2
Tv< Tc hence, safe
90
Check Trial Depth for one way shear (Along Z Axis)
(Shear Plane Parallel to Z Axis)
DZ = 0.453 m
Percentage Of Steel(Pt) = 0.1558
As Per IS 456 2000 Clause 40 Table 19
Shear Strength Of Concrete(Tc) = 295.961 kN/m2
Tv< Tc hence, safe
Check Trial Depth for two way shear
Critical Load Case = #3

91
As Per IS 456 2000 Clause 31.6.3.1
Ks = = 1.000
Shear Strength(Tc)= = 1250.00 00 kN/m2
Ks x Tc = 1250.0000 kN/m2
Tv<= Ks x Tc hence, safe
Reinforcement Calculation
Calculation of Maximum Bar Size along X Axis
Bar diameter corresponding to max bar size (db) = 20 mm
As Per IS 456 2000 Clause 26.2.1
Development Length(ld) = =.806 m
Allowable Length(ldb) = = 0.825 m

ldb >=ld hence, safe
Along Z Axis
Bar diameter corresponding to max bar size(db) = 20 mm
As Per IS 456 2000 Clause 26.2.1
Development Length(ld) = = 0.806 m
Allowable Length(ldb) = = 0.875 m

ldb >=ld hence, safe
Bottom Reinforcement Design

Along Z Axis
92
For moment w.r.t. X Axis (Mx)
As Per IS 456 2000 Clause 26.5.2.1
Minimum Area of Steel (Astmin) = 1308.060 mm2
Calculated Area of Steel (Ast) = 1517.448 mm2
Provided Area of Steel (Ast,Provided) = 1517.448 mm2
Astmin<= Ast,Provided Steel area is
accepted
Selected bar Size (db) = Ø8
Minimum spacing allowed (Smin) = 48.000 mm
Selected spacing (S) = 68.067 mm
Smin <= S <= Smax and selected bar size < selected maximum bar size...
The reinforcement is accepted.
Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 65.000 mm
o.c.
Along X Axis
93
For moment w.r.t. Z Axis (Mz)
As Per IS 456 2000 Clause 26.5.2.1
Astmin<= Ast,Provided Steel area is accepted
Minimum spacing allowed (Smin) = = 50.000 mm
Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 75.000 mm
o.c.
Top Reinforcement Design
Along Z Axis
94
Astmin<= Ast,Provided
Steel area is accepted
Governing Moment = 75.780 kNm
Minimum spacing allowed (Smin) = 50.000 mm
Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 75 mm o.c.

Along X Axis
95
Astmin<= Ast,Provided
Steel area is accepted
Governing Moment =67.809kNm

Minimum spacing allowed (Smin) = = 50.000 mm

Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 75 mm o.c.
96

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ANNEXURE -A

(I) ISOLATED FOOTING DESIGN

Soil Type = Drained

Sliding and Overturning

Load Combination/s- Service Stress Level

Note: Amin is an initial estimation.

Final Footing Size

Pressures at Four Corner

Load Pressure at Pressure at Pressure at Pressure at Area of

Load Case Pressure at Pressure at Pressure at Pressure at

(kN/m2) (kN/m2) (kN/m2) (kN/m2)

Check for Stability against Overturning and Sliding

- Factor of safety against sliding Factor of safety against

Load Case Along X- Along Z- About X- About Z-

Critical Load Case for Sliding along X-Direction = 3

Critical Load Case for Sliding along Z-Direction =3

Governing moment (Mu) = 241.764 kNm

= 1519.591251 kNm Limit Moment Of Resistance (Mumax) =

Check Trial Depth against moment (w.r.t. Z Axis)

Governing moment (Mu) = 207.221 kNm

Limiting Factor2 (Rumax) = = 3444.29114 kN/m2 Limit Moment Of Resistance (Mumax) =

Mu <= Mumax hence, safe

Check Trial Depth for one way shear (Along X Axis)

Critical Load Case = #3

Development Length(ld) = =.806 m

Allowable Length(ldb) = = 0.825 m

Allowable Length(ldb) = = 0.875 m

Bottom Reinforcement Design

Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 75 mm o.c.

Provided Area of Steel (Ast,Provided) = 1308.060 mm2

Selected bar Size (db) = Ø8

Selected spacing (S) = 78.538 mm

Based on spacing reinforcement increment; provided reinforcement is Ø8 @ 75 mm o.c.

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