Copy of Combined Footing-1

Data :

Size of column C1 = 0.75 x 0.75


Distance between Columns = 1.79 m

Grade of concrete = 25 N/mm2

Grade of steel = 415 N/mm2

xumax / d = 0.48

Ru = 3.46

Load on column C1 ( W1 ) = 124.40 KN

Load on column C2 ( W2 ) = 121.77 KN

Safe bearing capacity of soil = 250 KN/m2

Total load on footing = 270.79 KN

Required area of Footing = 1.08 m2

Moment About X-Axis (Mux1) = 26.29 KN-m

Moment About X-Axis (Mux2) = 21.61 KN-m

Moment About Z-Axis (Muz1) = 25.19 KN-m

Moment About Z-Axis (Muz2) = 19.70 KN-m

Total load on footing ( W = 1.1P ) = 270.79 KN

Safe bearing capacity of soil ( gsafe ) = 250 KN/m2

Area of Footing required (Areq = W /g safe) = 1.08 m2

Size of Footing Required (Bf x Lf) = 3 x 0.36

Provided size of the footing = 3 x 2.25

Plan of Footing :

Size of the footing = 3 x 2.25

Area of footing = 6.75 m2

Distance of C.G.of loads from centre of C1 = 0.89 m

Projection of footing from C1 , x1 = 0.600 m


DESIGN OF COMBINED FOOTING

Net upward pressure = 24.67 KN / m2

z

3000

C1 C2

890 C.G

2250 x

0.75 X 0.75 0.75 X 0.75

600 1790 610

25.2 z 19.70 About z

26.3 21.61 About x

124.4 121.775

0.6 1.79 0.61

83.25 KN/m

5071

1.5

SFD 51

74

10.21

1.5

15.49

14.99 BMD 35.19

Net upward pressure per metre run = 83.25 KN/m

Distance of max. B.M.from left end of footing = 1.5 m

Max. positive bending moment = 15.49 KN-m

Shear Force at the centre of C1 ( V1 ) = 74 KN


Depth from max. B.M.consideration = 45 mm

Max. negative bending moment = 0.00 KN-m


Provide Depth = 300 mm

Effective Depth = 240 mm

Check for Bearing

(P/A) + (6*Mx/AB2) + (6*Mz/A

2B) = 45.80 < 250 SAFE P1

(P/A) - (6*Mx/AB2) + (6*Mz/A

2B) = 20.57 < 250 SAFE P2

(P/A) - (6*Mx/AB2) - (6*Mz/A

2B) = 2.83 < 250 SAFE P3

(P/A) + (6*Mx/AB2) - (6*Mz/A

2B) = 28.06 < 250 SAFE P4

Footing is Safe in bearing

45.8 28.06

B

20.57 2.83 A

Reinforcement @ middle:

Mu / Bf d2 = 0.00

% of Steel Pt required from SP: 16 = 0.12

Required Steel (Ast req) = 648 mm2

Dia Of Bars Provided ( f ) = 10 mm

Area Of each 10 mm dia bar = 78.54 mm2

No: Of 10 mm dia bars (required) = 8 Nos.

Spacing of main bars required ( Sreq ) = 281 mm

Provide main bars @ Spacing ( S ) = 200 mm

Reinforcement @ ends:

Mu / Bf d2 = 0.12








Area provided = 884 mm2

pt. = 0.17 %

Min. Steel = 648 mm2

Dia. Of min. steel = 10 mm

Area of each bar = 78.54 mm2

Spacing of min. steel required = 272.71 mm

Provide Spacing = 200 mm

Transverse reinforcement under column C1:

Factored upward pressure under column C1 = 44.95 KN/m2

Bending at the face of column = 12.64 KN-m

Mu / Bf d2 = 0.18


Required Steel (Ast req) = 354.24 mm2







pt. = 0.2 %

Min. Steel = 354.24 mm2



Spacing of min. steel required = 1090.83 mm





Mu / Bf d2 = 0.18


Required Steel (Ast req) = 354.24 mm2






Area provided = 591.02 mm2

pt. = 0.17 %

CHECK FOR ONE WAY SHEAR :

Shear Force under Left Column @ d from face = -0.4 KN

Shear Force, Vu = -0.4 KN

Shear Stress,tv = 0.00 N/mm2

Permissible shear stress in concrete ( tc ) = 0.31 N/mm2

> 0.00

Footing is Safe in One Way Shear

CHECK FOR PUNCHING :

Critical width, bo = 0.99 m

Punching Shear Force at C1, Vu = 88.14 KN

Shear Stress, tv = 0.08 N/mm2

Permissible Shear Stress, tc = 1.25 N/mm2

> 0.08

Footing is Safe in Punching Shear

Dimension:

3 x 2.25 x 0.3

Reinforcement:Long Span:

Mid Span: Top 10 T @ 200 c/c

Bottom 10 T @ 200 c/c

End Span: Top 10 T @ 200 c/c


Short Span:

Top 10 T @ 200 c/c


Data :



Distance between Columns = 1.265 m

Grade of concrete = 25 N/mm2

Grade of steel = 415 N/mm2

xumax / d = 0.48

Ru = 3.46

Vertical Load on column C1 = 18 KN

Self weight of column C1 = 25 x 0.5625 x 5.84

= 82.13 KN

Load on column C1 ( W1 ) = 1.5 x 18.00 + 82.13

= 150.19 KN

Vertical Load on column C2 = -4.00 KN

Self weight of column C2 = 25 x 0.5625 x 6.47

= 90.98 KN

Load on column C2 ( W2 ) = 1.5 x -4 + 90.98

= 130.48 KN

Safe bearing capacity of soil = 250 KN/m2

Total load on footing = 308.73 KN

Required area of Footing = 1.23 m2

Total load on footing ( W = 1.1P ) = 308.73 KN

Safe bearing capacity of soil ( gsafe ) = 250 KN/m2

Area of Footing required (Areq = W /g safe) = 1.23 m2

Size of Footing Required (Bf x Lf) = 3 x 0.41

Provided size of the footing = 3 x 2.5

Plan of Footing :

Size of the footing = 3 x 2.5

DESIGN OF COMBINED FOOTING -2

Area of footing = 7.5 m2

Distance of C.G.of loads from centre of C1 = 0.59 m



Net upward pressure = 150.19 + 130.48 1.5 x 3.0 x 2.50

= 25.33 KN / m2

3000

C1 C2

590 C.G

2500

0.75 X 0.75 0.75 X 0.75

870 1265 865

150.19 130.48

0.87 1.265

95 KN/m

83 48

1.58

SFD

68 11.95 82

1.58

35.96 BMD 35.55

Net upward pressure per metre run = 25.33 x 2.5 x 1.5

= 95 KN/m

Distance of max. B.M.from left end of footing = 150.19 95

= 1.58 m

Max. positive bending moment = 35.96 KN-m

0.865




Max. negative bending moment = 11.95 KN-m


Provide Depth = 750 mm

Effective Depth = 690 mm

Check for Bearing

(P/A) = 24.95 < 250 SAFE

Reinforcement @ middle:

Mu / Bf d2 = 0.010








Reinforcement @ ends:

Mu / Bf d2 = 0.03









pt. = 0.17 %




Spacing of min. steel required = 137 mm





Mu / Bf d2 = 0.020









pt. = 0.12 %




Spacing of min. steel required = 137 mm





Mu / Bf d2 = 0.01









pt. = 0.17 %

CHECK FOR ONE WAY SHEAR :

Shear Force under Left Column @ d from face = 82.7 - 95.0 x 0.69

= 17.10 KN

Shear Force, Vu = 17.1 KN

Shear Stress,tv = 0.010 N/mm2

Permissible shear stress in concrete ( tc ) = 0.31 N/mm2

> 0.010

Footing is Safe in One Way Shear

CHECK FOR PUNCHING :

Critical width, bo = 1.44 m

Punching Shear Force at C1, Vu = 150.19- 25.33 x 1.44 ^2

= 97.66 KN

Shear Stress, tv = 0.04 N/mm2

Permissible Shear Stress, tc = 1.25 N/mm2

> 0.04

Footing is Safe in Punching Shear

Dimension: 3 x 2.5 x 0.75

Reinforcement:Long Span:

Mid Span: Top 12 T @ 100 c/c


End Span: Top 12 T @ 100 c/c

Bottom 12 T @ 100 c/cShort Span: Top 12 T @ 100 c/c


Copy of Combined Footing-1

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