All Type of Footing Design

7/28/2019 All Type of Footing Design

1/23

Isolated Footing by Limit State Method

Data Required/assumed

Safe Bearing Capacity of the soil = 50 KN/m2 P = 87 Kn

M20 fck = 25 N/mm2 Mx = 0 Kn-m

FE415 Fe = 415 N/mm2 My = 0 Kn-m

Depth of soil above footing = 1.1 m Zx = 0.56 m3

Provide Overal Depth of footing = 350 mm Zy = 0.56 m3d = 300 mm net soil reaction = 38.67 KN/m2

Min Eff. depth required = 50 mm net soil reaction = 38.666667

Footing dimensions Considering only loads

B = 1.5 m

L = 1.5 m

Column dimensions

a = 500 mm

b = 500 mm

Load from Column = 87 KN

Net soil reaction = 38.67 KN/m2

B. M. at the face of column =

x = 0.5 Mxx = 7.250 KN-m/m length

y = 0.5 Myy = 7.250 KN-m/m length

Xumax = 144 mmMulimit = 310.42 Kn-m

Mulimit>M, Hence Section is Under reinforced

Designing as Under reinforced section xu=0.87.fy.Ast/0.36.fck.b

Astx = 67.22 mm2

Asty = 67.22 mm2

Ast min = 420 mm2 Astlimit= 3589.53 mm2

Provide Astx 10 mm bar @ 180 mm C/C AstxW.S.M 77.83 mm2

Provide Asty 10 mm bar @ 180 mm C/C 44.4E+6 KN-M

420.00 mm2

Check for One Way Shear

420.00

Factored Shear Vu = 11.60 KN

Tv = 0.039 p = 0.140

Tc = 0.282 From Code Using formula

Tv


2/23

Isolated Footing by Limit State Method (To b Modify)


Safe Bearing Capacity of the soil = 90 KN/m2 P = 40

M20 fck = 20 N/mm2 Mx = 10

FE415 Fe = 415 N/mm2 MZ = 15

Depth of soil above footing = 1.5 m Zx = 4.97Provide Overal Depth of footing D = 500 mm Zz = 4.97

d = 442 mm 9.20T 250 mm Net soil reaction = 4.16

Footing dimensions L = 3.1 m

B = 3.1 m Astlimit = 4230.86

Column dimensions a = 300 mm AstxW.S.M = 184.04

b = 500 mm M.R = 152.0E+6

CALCULATIONS

Load from Column = 40 KN

Net soil reaction = 9.20 KN/m2

B. M. at the face of column Mxx = 25.26 KN-m/m length

Myy = 30.20 KN-m/m length

dxxreq = 95.66 mm

dyyreq = 104.60 mm 16.84

Astx = 159.55 mm2

Asty = 191.02 mm2

Ast min = 1000 mm2

Provide Astx 1000.00 mm2 16 mm tor @ 200 mm C/C

Provide Asty 1000.00 mm2 16 mm tor @ 200 mm C/C



Tv = 0.027 p = 0.226


Tv


3/23

Kn

Kn-m

Kn-m

m3m3

KN/m2

KN/m2

mm2

mm2

KN-M


4/23

Combined Footing by Limit State Method

Safe Bearing Capacity of the soil = 80 KN/m2 W1= 450 KN

M20 fck = 20 N/mm2 W2= 100 KN

Fe415 Fe = 415 N/mm2 Mx= 90 KN-m

Provide Overal Depth of footing D = 500 mm Mz= 100 KN-m

d = 440 mm a1= 1 mDepth above footing = 1.55 m C= 3 m

Footing dimensions Af= 7.56 m2

B = 2.50 m x-= 0.545 m

L = 7.00 m L= 3.1 m

Column dimensions a1 = 600 mm B= 2.45 m

a2 = 600 mm a2= -0.9 m

b1 = 500 mm s1= 0.700 m

b2 = 500 mm s2= -1.209 m STRES

Net soil reaction = 49.55 KN/m2 Zx= 20.417 m3

UDL for long. BM= R.B 185.82 KN/m2 Zz= 7.292 m3

UDL for Trans. BM=R.1 74.33 KN/m2

Longitudinal BMDM1= w.s1 /2 M1 = 45.53 KN-m

M2=w.s2 /2 M2 = 677.30 KN-m

x= 3.63 Mx = 551.01 KN-m

Xumax = 211.2 Mulimit = 1335.49 Kn-m

Longitudinal Steel Astmin = 880 mm2

Ast1 = 880 mm2 16 @220 C/C > Astmin

Ast2 = 2978 mm2 16 @60 C/C > Astmin

Top Ast = 1494 mm2 16 @130 C/C Or 24 Nos

> Astmin

Transverse steel

t1 = 1 Mt1 = 37.16 KN-m 1493.2

t2 = 1 Mt2 = 37.16 KN-m

Astmin = 1000 mm2

AstT1 = 1000 mm2 16 @200 C/C Min.Steel

AstT2 = 1000 mm2 16 @200 C/C > Astmin

Design of shear Two Way Shear (Punching)

Critical section 1 Under column 1

x1=s1+b1+d = 1.74 Tvv 0.2166

V1 = 126.68 p = 0.1358 Tcc 1.1180

Tv = 0.1152 Tvv < Tcc hence safe

Tc = 0.2751 Tv


5/23

COMBINED FOOTING DESIGN BY SURAJ


6/23

88.99445

t1 t2

s1d d d2

ast1 ast2

Ast

Transeverse steel

a2

s2

c

a2

s2

c

Top level steel

Bottom level steel

Ast2

Ast1AstT1

Ast

W1W2c

W1+W2x-



7/23

0.287509 0.15



8/23



9/23



10/23

Combined Footing Using Limit State Method

Data Required/assumed W1 800 KN

Safe Bearing Capacity of the soil = 90 KN/m2 W2 1410 KN

M20 fck = 20 N/mm2 W3 1350 KN

FE415 Fe = 415 N/mm2 Mx1 0.98 KN-m

Provide Overal Depth of footing = 600 mm Mx2 9.67 KN-md = 540 mm Mx3 9.59 KN-m

Depth above footing = 2.5 m Mz1 2.88 KN-m

Footing dimensions Mz2 6.93 KN-m

B = 3 m Mz3 2.66 KN-m

L = 18.3 m Af 43.51 mm2

Column dimensions a1 1.5 m

b1 = 700 mm c1 6.2 m

b2 = 700 mm c2 6.2 m

l1 = 700 mm x- 7.158 m

l2 = 700 mm L 17.3 m

Net soil reaction = 66.91 KN/m2 B 2.51 m

UDL for long. BM= R.B 301.10 KN/m2 a2 3.4 mUDL for Trans. BM=R.1 100.37 KN/m2 s1 1.150 m

s2 3.066 m

Zx 167.445 m3

Longitudinal BMD M1= w.s12/2 199.10 KN-m Zz 27.450 m3

M2=w.s22/2 2469.42 KN-m

M3 1414.99 KN-m

x= 2.66 Mx 137.24 KN-m


Mxx and Myy>Mulimit, Hence Section is over reinforced

Transeverse steel

t1 = 1.15 Mt1 66.37 KN-m

t2 = 1.15 Mt2 66.37 KN-md trans

Longitudinal Steel Astmin = 1200 mm2

Ast1 = 1200 mm2 > Astmin 20

Ast2 = 15918 mm2 > Astmin 20

Top Ast = 1200 mm2 > Astmin 20

Top No.of bars 12 11

Transverse steel Astmin = 1200 mm2

AstT1 = 1200 mm2 Provide Minimum Steel 20

AstT2 = 1200 mm2 Provide Minimum Steel 20

Design of shear

Critical section 1

x1=s1+b1+d = 2.39

V1 = 80.36 p = 0.074074

Tv = 0.0496

Tc = 0.2090

Tv


11/23

x2=s2+b2+d = 4.3057303

V2 = 113.53

Tv = 0.0701

Tv


12/23

944.1

51.225

240.435

69.2246812

15

@260 C/C

@10 C/C

@260 C/C

@260 C/C

@260 C/C

`

t1 t2

s1d d d2

ast1 ast2

Ast

Transeverse steel

a2

s2

c

a2

s2

c

Top lev

Bottom

Ast2

Ast1AstT1

Ast

W1 W2c

W1+W2x-


13/23


14/23

el steel

level steel


15/23

Combined Footing by Limit State Method (beam slab)

Data Required W1 800 KN

Safe Bearing Capacity of the soil = 150 KN/m2 W2 800 KN

M20 fck = 15 N/mm2 Mx 4.5 KN-m

FE415 Fe = 250 N/mm2 Mz 4.5 KN-m

Width of beam b = 400 mm a1 1.4 m

Column dimensions b1 = 400 mm c 4.2 m

b2 = 400 mm depth 2.5 m

l1 = 400 mm

l2 = 400 mm

Af 11.73 mm2

x- 2.1 m

Footing dimensions L 7 m

B = 1.7 m B 1.7 m

L = 7 m a2 1.4 m

Size is adequate w.r.t S.B.C s1 1.2 m

Net soil reaction = 136.36 KN/m2 s2 1.2 m

UDL for long. BM= R.B 228.57 KN/m2 Zx 3.28 mm3

UDL for Trans. BM=R.1 136.36 KN/m2 Zz 13.69 mm3

Slab is designed to resist transeverse bending

Transeverse steel

t1 = 0.638 Mt1 41.64 KN-m

t2 = 0.638 Mt2 41.64 KN-m

d Reqd = = 136.96 mm

Provide Overal Depth of footing D = 190 mm

d = 144 mm

Xumax = 76.32 Mulimit = 46.14 Kn-m M Astmin

AstT2 = 1482 mm2 > Astmin

Astmin = 285 mm2

Provide Distribution steel of Astmin 8 mm bar @ 170 mm C /C

Design of beam

Longitudinal BMD M1= w.s12/2 246.86 KN-m b = 400

M2=w.s22/2 246.86 KN-m d = 534

M3 246.86 KN-m D = 590


M Astmin

Ast2 = 2692 mm2 > Astmin

x= 3.5 Mx = 280.00 KN-m

Top steel is to resist BM of 280.00 KN-m as inverted T-beam Action

Lo = 3.13 mbf = 0.934 m

Mulimit = 592.27 Kn-m

M Mx: Section is safe under Bending

Design of shear


16/23

Critical section 1

x1=s1+b1+d = 2.134

V1 = 68.34

Tv = 0.3200

Tc = 0.2033 Tv>Tc Design for shear

Providing 2-legged 8 150mm C/C

Critical section 2

x2=s2+b2+d = 2.134 Min. spacing is lesser of following

V2 = 68.34 a. Asv/b.Sv=0.4/fy

Tv = 0.3200 b. 0.75*d

Providing 2-legged 8 150mm C/C c. 450mm

Critical section 3 d. 0.87.fy.Asv.d/(Tv-Tc)b.d if Tv>Tc

x3=s2-d2 = 0.666

V3 = 152.23

Tv = 0.1701

Tc = 0.2033 Tv


17/23

`


18/23

Strap Footing:

Data Required

Safe Bearing Capacity of the soil SBC = 150 KN/m2

Allowable stress in Concrete M20 fck = 15 N/mm2

Allowable stress in steel Fe 415 Fy = 415 N/mm2

Width of beam b = 400 mm

Column sizes b1 = 300 mm

b2 = 400 mm

b3 = 0 mm

Loads from columns W1 = 600 KN

W2 = 900 KN

W3 = 0 KN

L1 = 3 m

a1 = 0.15 m

Distance bet columns c = 5 m

Area of footing Af = 11.00 m2

CG of fooing x- = 2 m

Footing dimensions L2 = 2.475 m

B = 2.0 m

a2 = 1.2375 m

Gap = 0.9125 m

s1 = 0 m

s2 = 1.0375 m

Net soil reaction R = 136.36 KN/m2

UDL for long. BM= R.B wLong = 273.97 KN/m2

UDL for Trans. BM=R.1 wTrans = 136.36 KN/m2

Design of Cantilever Slab

Cantilever projection x = 0.80 m

Max. Bm in Slab Mmax = 66.20 KN-m

Dreq = 230 mm

-

L2

+


19/23

d = 184 mm

xumax = 121.92 mm

Mulimit = 167.23 KN-m MTc, Design of shear is reqd., Increase Depth of footing to, d = 254

Provide Overal depth of footing 300 mm

Ast = 791 mm2 12 mm bar @ 90

Astmin = 360 mm2 8 mm bar @ 130

Design of Beam

Max BM Mmax = 850.50 KN-m x = 2.19 m

BM at end of footing M = 715.68 KN-m x = L1 =3 m

BM corresponding to s2 M2 = 221.18 KN-m x = 5.35 m

BM at the end of right side footing M = 411.93 KN-m x = 3.9125 mMulimit = 715.95 KN-m xumax = 446.4

Depth req. as per T-beam action d =

Depth req. as/ rect. beam action d = 930 mm

Provide overall depth of steel D = 1000 mm

Area of steel

Top steel in beam Ast = 3388 mm2

Astmin = 762 mm2

Provide 12 Nos 20 TOR in two row, total Ast= 3770 mm2

steel at bottom Ast = 762 mm2

Provide 4 Nos 20 TOR total ast= 1257 mm2Check for moment of resitance MR = IF((0.87*E17*I53/(0.36*E16*F4 bf= Lo/(Lo/b+4)+bw

Area of side face steel Astside = 400 mm2

Provide 3 Nos 10 TOR bar in each face BUT spacing


20/23

G1


21/23

m

mm C/C As main steel

mm C/C as distribution


22/23

Isolated Circular Footing by Limit State Method


Safe Bearing Capacity of the soil = 80 KN/m2 P = 517.4

M20 fck = 20 N/mm2 Mx = 25

FE415 Fe = 415 N/mm2 Zx = 5.18

Depth of soil above footing h = 1.5 m 51.68Provide Overal Depth of footin D = 700 mm Cons loads only 46.85

deff = 642 mm M.R = 654.70

T 300 mm Astlimit = 6145.28

Diameter of footing D = 3.75 m AstxW.S.M = 1807.40

Column dimensions d = 3.5 mm

CALCULATIONS side = 2.47 m Tv>Tc Unsafe

Load from Column = 517.4 KN

Upword soil pressure at face of column = 214.02 KN

B. M. at the face of column x = 1.12 m

Mxx = 240.19 KN-m

dxxreq = 187.71 mmAst = 1046.18 mm

2

Ast min = 3150 mm

Provide 16 Nos 16 mm tor in each direction at right angles to each oth



Tv = 0.291 p = 0.131


Tv>Tc Unsafe

Check for Two Way Shear

Two way shear = 830.734 KN

Tvv = 0.638

Allowable shear = 1.118Tvv < Tcc hence safe


23/23

Kn

Kn-m

m3

KN/m2KN/m2

KN-M

mm

mm

Data req for WSM

j 0.9

st 230

cbc 7

m 13.33

x1 0.29

j 0.90Q 0.91

%steel 0.439

er

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All Type of Footing Design