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Isolated Footing For Columns

This document summarizes the design of a footing (F1) including: - Input parameters such as concrete grade, steel grade, soil properties, footing and column dimensions - Calculation of dead loads from soil and concrete - Load inputs from structural analysis software - Checks for base pressure, shear stress, punching shear, and reinforcement design meet code requirements - Footing reinforcement is designed and spacing is provided to resist bending and shear stresses All check calculations show the footing design is safe and code compliant.

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kushaljp8989
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499 views8 pages

Isolated Footing For Columns

This document summarizes the design of a footing (F1) including: - Input parameters such as concrete grade, steel grade, soil properties, footing and column dimensions - Calculation of dead loads from soil and concrete - Load inputs from structural analysis software - Checks for base pressure, shear stress, punching shear, and reinforcement design meet code requirements - Footing reinforcement is designed and spacing is provided to resist bending and shear stresses All check calculations show the footing design is safe and code compliant.

Uploaded by

kushaljp8989
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLSX, PDF, TXT or read online on Scribd
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SL.

No DESCRIPTION REFERENCE
1 FOOTING DESIGN- F1
1.1 INPUT
Grade of concrete fck 25 N/mm2
Grade of steel fy 500 N/mm2
Density of soil ρs 1.8 T/m3
Density of concrete ρc 2.5 T/m3
Depth from FGL D 3.0 m
Ht of Column above FGL h 0.0 m
SBC of soil 30 T/m2
Clear Cover to reinforcement(Earth face) 0.075 m
Clear Cover to reinforcement 0.05 m
L B d
Size of Raf 1.8 0.75 0.5 m
Size of Column 0.8 0.5 2.5 m
1.2 DEAD WEIGHT OF SOIL AND CONCRETE
Area of Footing
= (LxB) 1.35 m2
Weight of Concrete
= Vol of Raf x density of Concrete 1.69 T
Weight of Soil
= (Area of footing - Area of Column) x (depth of
foundation - depth of raf) x density of Concrete 4.28 T
1.3 SECTION MODULUS
Zxx = L x B2/6 0.17 m3
Zzz = B x L2/6 0.41 m3
1.4 LOAD INPUT FROM STAAD
All loads are in "Tons"
Critical Load C
Sl no. Combinations
Fx Fy Fz Mx My Mz
1 13 0.06 5.01 0.02 0.00 0.00 -0.10
2 29 -0.37 11.91 -0.03 0.00 0.00 0.57
3 44 -0.23 13.92 -0.55 0.00 0.00 0.36
4 20 -0.06 3.74 -0.55 0.00 0.00 0.04
5 36 -0.24 11.27 0.61 0.00 0.00 0.41
6 34 -0.24 13.18 -0.60 0.00 0.00 0.40
7 33 -0.24 11.88 -0.03 0.00 0.00 0.39
8 33 -0.24 9.94 0.03 0.00 0.00 0.38
9 29 -0.37 11.91 -0.03 0.00 0.00 0.57
10 13 0.06 5.01 0.02 0.00 0.00 -0.10
1.5 BASE PRESSURE CHECK Base Pressure
P1 P2 P3 P4 P=(Fy/A) ± (M'x/Zxx) ±
(M'z/Zzz)
7.9 7.9 8.4 7.9
14.6 11.8 14.6 11.8
15.6 13.8 15.6 13.8
7.3 7.1 7.3 7.1
13.8 11.7 13.8 11.7
15.2 13.2 15.2 13.2
14.2 12.3 14.2 12.3
12.7 10.8 12.7 10.8
14.6 11.8 14.6 11.8
7.9 7.9 8.4 7.9
Pmax 15.63 T/m2
Pmin 7.09 T/m2
1.6 CONVERTING NEGETIVE PRESSURE TO POSITIVE PRESSURE
To calculate Qmax 7.09 Interpolation method
To find out X X
i.e (+VE Pr) + (-VE Pr)/span= +VE Pr/x
X = 1.238
P = 1/2 x (+ve pr) x span
P = 14.07 T 15.63
P = 1/2 x Qmax x X 1.80
Qmax = 22.7 T/m2
SBC shall be increased by 33% for wind load As per IS 875 Part-3
Allowable SBC = 39.9 T/m2
IF Qmax < Allowable SBC SAFE
Hence Base pressure W 15.63 T/m2
1.7 DESIGN OF RAFT
Bottom Reinforcement - Xdirection
Cantilever bending moment
Cantilever distance lx 0.5 m
At support Mx= W X lx /2 2
Mx 2.0 T-m
Partial factor of safety 1.5
Ultimate moment in x dir Mux 2.9 T-m
Mux / bd2 0.16 N/mm2
Required Min
ANNEX G-1.1 IS456:2000
Percentage of steel Ptx = 0.038 0.12 %
Hence Ptx 0.12 % Cl.26.5.2.1 IS456:2000
Required Area of steel Astx 510 mm2 Astx = (Ptxbxd)/100

Providing 12 dia 200 Spacing


Provided Area of steel Astx 565 mm2 Astx=π xdia2/4xspacing
Provided percentage of steel Ptx 0.13 %
Bottom Reinforcement - Y direction
Cantilever bending moment
Cantilever distance ly 0.125 m
At support My= W X ly /2 2
My 0.12 T-m
Partial factor of safety 1.5
Ultimate moment in y dir Muy 0.2 T-m
Muy / bd 2
0.01 N/mm2
Required Min
ANNEX G-1.1 IS456:2000
Percentage of steel Pty 0.00 0.12 %
Hence Pty 0.12 % Cl.26.5.2.1 IS456:2000
Required Area of steel Asty 510 mm2 Asty = (Ptxbxd)/100

Providing 12 dia 200 Spacing


Provided Area of steel Asty 565 mm2 Asty=π xdia2/4xspacing
Provided percentage of steel Pty 0.13 %
Top Reinforcement - X&Ydirection Min
Providing 0.06% of Raf area(Both X and Y dir) Pt 0.06 %
Required Area of steel Ast 270 mm2
Providing 10 dia 200 Spacing
Provided Area of steel Ast 393 mm2
Provided percentage of steel Pt 0.09 %
1.8 CHECK FOR SINGLE SHEAR
SHEAR CHECK IN X DIR
Shear distance in cantilever portion dx 0.075 m
Shear force in X- dir Vx 2.1 T Vx = W X L X dx

Shear stress along X-dir τvx=Vx/Bd 0.04 N/mm2 Cl 40.1 (IS 456 :2000)
Maximum Shear Stress of Concrete τc (max) 3.10 N/mm2 Table-20 (IS 456 :2000)
Pt provided Ptprovd 0.13 %
Beeta = 0.8Xfck/6.89XPt β 21.8 1.00 Cl 4.1 (SP-16:1980)

Design shear strength of concrete τc 0.28 N/mm2 Cl 4.1 (SP-16:1980)

τc = (0.85 X sqrt(0.8fck)X sqrt(1+(5β-1)))/6β


Hence τv < τc SAFE
SHEAR CHECK IN Y DIR
Shear distance in cantilever portion dy -0.3 m
Shear force in Y- dir (Vy) Vy -3.5 T Vy = W X B X dy

Shear stress along Y-dir(Tvy) τvy=Vy/Bd -0.17 N/mm2 Cl 40.1 (IS 456 :2000)
Maximum Shear Stress of Concrete τc (max) 3.10 N/mm2 Table-20 (IS 456 :2000)
Pt provided Ptprovd 0.09 %
Beeta = 0.8Xfck/6.89XPt β 31.4 1.00 Cl 4.1 (SP-16:1980)

Design shear strength of concrete τc 0.23 N/mm2 Cl 4.1 (SP-16:1980)

τc = (0.85 X sqrt(0.8fck)X sqrt(1+(5β-1)))/6β


Hence τv < τc SAFE
1.9 CHECK FOR PUNCHING SHEAR
Perimeter of critical section bo 4.3 m
Area of critical section A 1.133 m2
Shear Vu 5 T/m2
= W X (LXB) of Raf-area
τv = Vu/bod 0.03 N/mm2 IS456:2000 cl.31.6.2.1

τc = 0.25 xsqrt fck 1.25 N/mm2 IS456:2000 cl.31.6.3.1


IF τc>τv τc > τv SAFE
SL.No DESCRIPTION REFERENCE
1 FOOTING DESIGN- F1
1.1 INPUT
Grade of concrete fck 25 N/mm2
Grade of steel fy 500 N/mm2
Density of soil ρs 1.8 T/m3
Density of concrete ρc 2.5 T/m3
Depth from FGL D 3.0 m
Ht of Column above FGL h 0.0 m
SBC of soil 30 T/m2
Clear Cover to reinforcement(Earth face) 0.075 m
Clear Cover to reinforcement 0.05 m
L B d
Size of Raf 1.8 0.75 0.5 m
Size of Column 0.8 0.5 2.5 m
1.2 DEAD WEIGHT OF SOIL AND CONCRETE
Area of Footing
= (LxB) 1.35 m2
Weight of Concrete
= Vol of Raf x density of Concrete 1.69 T
Weight of Soil
= (Area of footing - Area of Column) x (depth of
foundation - depth of raf) x density of Concrete 4.28 T
1.3 SECTION MODULUS
Zxx = L x B2/6 0.17 m3
Zzz = B x L2/6 0.41 m3
1.4 LOAD INPUT FROM STAAD
All loads are in "Tons"
Critical Load C
Sl no. Combinations
Fx Fy Fz Mx My Mz M'x = (Fz X D) + Mx
1 13 0.06 5.01 0.02 0.00 0.00 -0.10 M'z = (Fx X D) + Mz
2 29 -0.37 11.91 -0.03 0.00 0.00 0.57
3 44 -0.23 13.92 -0.55 0.00 0.00 0.36
4 20 -0.06 3.74 -0.55 0.00 0.00 0.04
5 36 -0.24 11.27 0.61 0.00 0.00 0.41
6 34 -0.24 13.18 -0.60 0.00 0.00 0.40
7 33 -0.24 11.88 -0.03 0.00 0.00 0.39
8 33 -0.24 9.94 0.03 0.00 0.00 0.38
9 29 -0.37 11.91 -0.03 0.00 0.00 0.57
10 13 0.06 5.01 0.02 0.00 0.00 -0.10
1.5 BASE PRESSURE CHECK Base Pressure
P1 P2 P3 P4 P=(Fy/A) ± (M'x/Zxx) ±
(M'z/Zzz)
7.9 7.9 8.4 7.9
14.6 11.8 14.6 11.8
15.6 13.8 15.6 13.8
7.3 7.1 7.3 7.1
13.8 11.7 13.8 11.7
15.2 13.2 15.2 13.2
14.2 12.3 14.2 12.3
12.7 10.8 12.7 10.8
14.6 11.8 14.6 11.8
7.9 7.9 8.4 7.9
SL.No DESCRIPTION REFRENCE
Pmax 15.63 T/m 2

Pmin 7.09 T/m2


1.6 CONVERTING NEGETIVE PRESSURE TO POSITIVE PRESSURE
To calculate Qmax 7.09 Interpolation method
To find out X X
i.e (+VE Pr) + (-VE Pr)/span= +VE Pr/x
X = 1.238
P = 1/2 x (+ve pr) x span
P = 14.07 T 15.63
P = 1/2 x Qmax x X 1.80
Qmax = 22.7 T/m2
SBC shall be increased by 33% for wind load As per IS 875 Part-3
Allowable SBC = 39.9 T/m2
IF Qmax < Allowable SBC SAFE
Hence Base pressure W 15.63 T/m2
1.7 DESIGN OF RAFT
Bottom Reinforcement - Xdirection
Cantilever bending moment
Cantilever distance lx 0.5 m
At support Mx= W X lx /2 2
Mx 2.0 T-m
Partial factor of safety 1.5
Ultimate moment in x dir Mux 2.9 T-m
Mux / bd2 0.16 N/mm2
Required Min
ANNEX G-1.1 IS456:2000
Percentage of steel Ptx = 0.038 0.12 %
Hence Ptx 0.12 % Cl.26.5.2.1 IS456:2000
Required Area of steel Astx 510 mm2 Astx = (Ptxbxd)/100

Providing 12 dia 200 Spacing


Provided Area of steel Astx 565 mm2 Astx=π xdia2/4xspacing
Provided percentage of steel Ptx 0.13 %
Bottom Reinforcement - Y direction
Cantilever bending moment
Cantilever distance ly 0.125 m
At support My= W X ly2/2 My 0.12 T-m
Partial factor of safety 1.5
Ultimate moment in y dir Muy 0.2 T-m
Muy / bd 2
0.01 N/mm2
Required Min
ANNEX G-1.1 IS456:2000
Percentage of steel Pty 0.00 0.12 %
Hence Pty 0.12 % Cl.26.5.2.1 IS456:2000
Required Area of steel Asty 510 mm2 Asty = (Ptxbxd)/100

Providing 12 dia 200 Spacing


Provided Area of steel Asty 565 mm2 Asty=π xdia2/4xspacing
Provided percentage of steel Pty 0.13 %
Top Reinforcement - X&Ydirection Min
Providing 0.06% of Raf area(Both X and Y dir) Pt 0.06 %
Required Area of steel Ast 270 mm2
Providing 10 dia 200 Spacing
Provided Area of steel Ast 393 mm2
Provided percentage of steel Pt 0.09 %
SL.No DESCRIPTION REFRENCE
1.8 CHECK FOR SINGLE SHEAR
SHEAR CHECK IN X DIR
Shear distance in cantilever portion dx 0.075 m
Shear force in X- dir Vx 2.1 T Vx = W X L X dx

Shear stress along X-dir τvx=Vx/Bd 0.04 N/mm2 Cl 40.1 (IS 456 :2000)
Maximum Shear Stress of Concrete τc (max) 3.10 N/mm2 Table-20 (IS 456 :2000)
Pt provided Ptprovd 0.13 %
Beeta = 0.8Xfck/6.89XPt β 21.8 1.00 Cl 4.1 (SP-16:1980)

Design shear strength of concrete τc 0.28 N/mm2 Cl 4.1 (SP-16:1980)

τc = (0.85 X sqrt(0.8fck)X sqrt(1+(5β-1)))/6β


Hence τv < τc SAFE
SHEAR CHECK IN Y DIR
Shear distance in cantilever portion dy -0.3 m
Shear force in Y- dir (Vy) Vy -3.5 T Vy = W X B X dy

Shear stress along Y-dir(Tvy) τvy=Vy/Bd -0.17 N/mm2 Cl 40.1 (IS 456 :2000)
Maximum Shear Stress of Concrete τc (max) 3.10 N/mm2 Table-20 (IS 456 :2000)
Pt provided Ptprovd 0.09 %
Beeta = 0.8Xfck/6.89XPt β 31.4 1.00 Cl 4.1 (SP-16:1980)

Design shear strength of concrete τc 0.23 N/mm2 Cl 4.1 (SP-16:1980)

τc = (0.85 X sqrt(0.8fck)X sqrt(1+(5β-1)))/6β


Hence τv < τc SAFE
1.9 CHECK FOR PUNCHING SHEAR
Perimeter of critical section bo 4.3 m
Area of critical section A 1.133 m2
Shear Vu 5 T/m2
= W X (LXB) of Raf-area
τv = Vu/bod 0.03 N/mm2 IS456:2000 cl.31.6.2.1

τc = 0.25 xsqrt fck 1.25 N/mm2 IS456:2000 cl.31.6.3.1


IF τc>τv τc > τv SAFE

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