Combined Isolated Footing

8/11/2019 Combined Isolated Footing

1/65

3.5

Y dir

Col A Col B

0.45 X dir

ETABS NODE NO. Col A=1 Col B=2

Conc grade = M20

Steel grade = Fe415

A) Proportioning of base size: -

Y - dir X - dir

Size of column A = 300 mm x 230 mm Additional

Size of column B = 300 mm x 230 mm MY

Ultimate load carrrid by column A = 307.5 kN 2

Ultimate load carrrid by column B = 303 kN 1

SBC of the soil = 200 kN/m2

Working load carrrid by column A = 205 kNWorking load carrrid by column B = 202 kN

Self wt of footing (10% of column load)= 41 kN

Total working load = 448 kN

Length of footing = 3.50 m

Requried area of footing = 2.24 m2

Width of footing = 0.64 m

Provide width of footing = 0.75 m

Provide Footing size of 3.50 m x 0.75 m = 2.63 m

2

As in this case, the property line is present on both end of column, hence there

is no possibility of projection, so the pressure will not be uniform if the c.g. of

footing and the c.g. of load does not coincide.

In such case fooring will become eccentric and hence the pressure will be non-uni

C.G of load system from end face of col A=

= ( 308 x 0.115 ) + ( 303 x 3.385 )


2/65

( 308 + 303 )

= 1.74 m

C.G. of footing = 1.75 m

Eccentricity of load w.r.t c.g. of footing = 0.01 m

Moment due to eccentricity = ( 407 x 0.01 ) = 5 kN m

Total Moment = 6 kN m

Pressure calculation :

Intensity of pressure due to Axial load = P / A =

= ( 205 + 202 ) / 2.63 = 155 kN/m2

Intensity of pressure due to Moment = M / Z =

= 6 / ( 0.75 x 3.50 x 3.50 ) / 6

= = 4 kN/m2

Pmax= ( 155 + 4 ) = 159 kN/m2

OK

Pmin= ( 155 - 4 ) = 151 kN/m2

OK

1

0.115 0.115

151

159 157 151

159

Load per metre run of slab = Avg pressure x 1 m

( 158 x 1.00 ) = 158 kN/m

Load per metre run of slab due to ultimate pressure =

( 158 x 1.50 ) = 237 kN/m

Cantilever projection of slab @ face of beam = = 0.15 m

Maximum ultimate moment = ( 237 x 0.15 x 0.15 ) = 32

d required = ( 3 x 10^6 ) = 31 mm

( 1000 x 2.76 )

Try overall depth = 230 mm Width = 1000

Effective depth d = 184 mm End depth= 175

Effective end depth d =

Ast= 40 mm2


3/65

Required is Y 8 @ 1247 mm

Provide Y 8 @ 200 mm = 251

Distribution steel = ( 0.12 % x 1000 x 203 ) = 243

Provide Y 8 @ 225 mm = 223

Shear @ d= -0.034 m

Shear = -8 kN

v = -0.06 N/mm2

Enter depth at d location

c = 0.355 N/mm2

(From SP16)

Section for depth is OK

Design of Longitudinal beam : -

307.5 303

1.62

0.115 3.27 0.115

170 170

174

179

179

Load Diagram

1.62 283.43

20.54 0.541

19.57

170.76

286.96 S.F.Diagram


4/65

-231.2201

1.18 1.13

B.M.Diagram

As in the central portion of beam, the moment is hogging, i.e. the tension is on th

top portion of beam, hence the beam at the central portion will be designed as th

isolated T- beam.

Reinforcement at the central portion:

bf= = 0.750 m

= 750 mm

bw= = 450 mm

Let provide depth of beam = 605 mm

Effective depth of beam = 541 mm

Ast= 1266 mm2

Provide 6 Nos. Y 16 mm 1206 mm2

0.30 %

Shear at d from face of column = 0.964 m

Shear = 171 kN

v = 0.70 N/mm2

c = 0.330 N/mm2

(From SP16)

Section for depth is PROVIDE STIRRUPS

Shear to be resisted by stirrups = 90.42 kN

Try stirrups of 2-legged Y 8 mm @ 217 mm

Provide Y 8 @ 200 mm = 251


5/65

SUMMARY: -

Provide Footing size of 3.50 m x 0.75 m

SLAB RENFORCEMENT: -

Provide Y 8 @ 200 mm


BEAM REINFORCEMENT: -TOP: - 9 Nos. Y 12 mm


6/65

oment

MX

2

2

orm.


7/65

kN m / metre

mm

mm

129 mm


8/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


9/65

27

685.8

mm2


10/65

3.5

Y dir

Col A Col B

0.45 X dir


Conc grade = M20

Steel grade = Fe415


Y - dir X - dir














2






= ( 386 x 0.115 ) + ( 372 x 3.385 )


11/65

( 386 + 372 )

= 1.72 m







= ( 257 + 248 ) / 2.98 = 170 kN/m2


= 13 / ( 0.85 x 3.50 x 3.50 ) / 6

= = 8 kN/m2

Pmax= ( 170 + 8 ) = 177 kN/m2

OK

Pmin= ( 170 - 8 ) = 162 kN/m2

OK

1

0.115 0.115

163

177 173 162

177


( 175 x 1.00 ) = 175 kN/m


( 175 x 1.50 ) = 263 kN/m



d required = ( 5 x 10^6 ) = 44 mm

( 1000 x 2.76 )




Ast= 80 mm2


12/65


Provide Y 8 @ 200 mm = 251


Provide Y 8 @ 225 mm = 223

Shear @ d= 0.016 m

Shear = 4 kN

v = 0.03 N/mm2


c = 0.355 N/mm2

(From SP16)



385.5 372

1.61

0.115 3.27 0.115

207 207

217

225

226

Load Diagram

1.61 348.18

25.96 0.692

23.82

179.32

359.54 S.F.Diagram


13/65


14/65

SUMMARY: -







15/65

oment

MX

2

1

orm.


16/65

kN m / metre

mm

mm

129 mm


17/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


18/65

mm2


19/65

3.5

Y dir

Col A Col B

0.45 X dir


Conc grade = M20

Steel grade = Fe415


Y - dir X - dir



Ultimate load carrrid by column A = 417 kN 2

Ultimate load carrrid by column B = 415.5 kN 2










2






= ( 417 x 0.115 ) + ( 416 x 3.385 )


20/65

( 417 + 416 )

= 1.75 m







= ( 278 + 277 ) / 2.98 = 187 kN/m2


= 4 / ( 0.85 x 3.50 x 3.50 ) / 6

= = 3 kN/m2

Pmax= ( 187 + 3 ) = 189 kN/m2

OK

Pmin= ( 187 - 3 ) = 184 kN/m2

OK

1

0.115 0.115

184

189 188 184

189


( 188 x 1.00 ) = 188 kN/m


( 188 x 1.50 ) = 283 kN/m



d required = ( 6 x 10^6 ) = 45 mm

( 1000 x 2.76 )




Ast= 86 mm2


21/65


Provide Y 8 @ 200 mm = 251


Provide Y 8 @ 225 mm = 223

Shear @ d= 0.016 m

Shear = 5 kN

v = 0.04 N/mm2


c = 0.355 N/mm2

(From SP16)



417 415.5

1.63

0.115 3.27 0.115

235 235

238

241

241

Load Diagram

1.63 388.51

27.72 0.692

26.99

196.55

389.28 S.F.Diagram


22/65

-314.2662

1.59 1.55

B.M.Diagram



isolated T- beam.


bf= = 0.850 m

= 850 mm

bw= = 450 mm



Ast= 1320 mm2


0.24 %


Shear = 197 kN

v = 0.63 N/mm2

c = 0.330 N/mm2

(From SP16)




Provide Y 8 @ 250 mm = 201


23/65

SUMMARY: -







24/65

oment

MX

2

1

orm.


25/65

kN m / metre

mm

mm

129 mm


26/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


27/65

mm2


28/65

3.5

Y dir

Col A Col B

0.45 X dir


Conc grade = M20

Steel grade = Fe415


Y - dir X - dir














2






= ( 441 x 0.115 ) + ( 441 x 3.385 )


29/65

( 441 + 441 )

= 1.75 m







= ( 294 + 294 ) / 3.33 = 177 kN/m2


= 2 / ( 0.95 x 3.50 x 3.50 ) / 6

= = 1 kN/m2

Pmax= ( 177 + 1 ) = 178 kN/m2

OK

Pmin= ( 177 - 1 ) = 176 kN/m2

OK

1

0.115 0.115

176

178 177 176

178


( 177 x 1.00 ) = 177 kN/m


( 177 x 1.50 ) = 266 kN/m



d required = ( 8 x 10^6 ) = 55 mm

( 1000 x 2.76 )




Ast= 127 mm2


30/65


Provide Y 8 @ 200 mm = 251


Provide Y 8 @ 225 mm = 223

Shear @ d= 0.066 m

Shear = 18 kN

v = 0.14 N/mm2


c = 0.355 N/mm2

(From SP16)



441 441

1.64

0.115 3.27 0.115

251 251

252

253

253

Load Diagram

1.64 412.16

29.12 0.692

28.84

209.21

411.88 S.F.Diagram


31/65

-333.9015

1.67 1.66

B.M.Diagram



isolated T- beam.


bf= = 0.889 m

= 889 mm

bw= = 450 mm



Ast= 1404 mm2


0.23 %


Shear = 209 kN

v = 0.67 N/mm2

c = 0.330 N/mm2

(From SP16)




Provide Y 8 @ 225 mm = 223


32/65

SUMMARY: -







33/65

oment

MX

1

1

orm.


34/65

kN m / metre

mm

mm

129 mm


35/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


36/65

mm2


37/65

3.5

Y dir

Col A Col B

0.45 X dir


Conc grade = M20

Steel grade = Fe415


Y - dir X - dir














2






= ( 414 x 0.115 ) + ( 408 x 3.385 )


38/65


39/65


Provide Y 8 @ 200 mm = 251


Provide Y 8 @ 225 mm = 223

Shear @ d= 0.066 m

Shear = 17 kN

v = 0.13 N/mm2


c = 0.355 N/mm2

(From SP16)



414 408

1.62

0.115 3.27 0.115

230 230

235

240

240

Load Diagram

1.62 381.57

27.58 0.692

26.43

193.92

386.42 S.F.Diagram


40/65

-311.9913

1.59 1.52

B.M.Diagram



isolated T- beam.


bf= = 0.889 m

= 889 mm

bw= = 450 mm



Ast= 1307 mm2


0.23 %


Shear = 194 kN

v = 0.62 N/mm2

c = 0.330 N/mm2

(From SP16)




Provide Y 8 @ 225 mm = 223


41/65

SUMMARY: -







42/65

oment

MX

2

2

orm.


43/65

kN m / metre

mm

mm

129 mm


44/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


45/65

mm2


46/65

3.5

Y dir

Col A Col B

0.45 X dir


Conc grade = M20

Steel grade = Fe415


Y - dir X - dir














2






= ( 317 x 0.115 ) + ( 237 x 3.385 )


47/65

( 317 + 237 )

= 1.52 m







= ( 211 + 158 ) / 2.63 = 141 kN/m2


= 62 / ( 0.75 x 3.50 x 3.50 ) / 6

= = 40 kN/m2

Pmax= ( 141 + 40 ) = 181 kN/m2

OK

Pmin= ( 141 - 40 ) = 100 kN/m2

OK

1

0.115 0.115

103

178 158 100

181


( 169 x 1.00 ) = 169 kN/m


( 169 x 1.50 ) = 254 kN/m



d required = ( 3 x 10^6 ) = 32 mm

( 1000 x 2.76 )




Ast= 43 mm2


48/65


Provide Y 8 @ 200 mm = 251


Provide Y 8 @ 225 mm = 223

Shear @ d= -0.034 m

Shear = -9 kN

v = -0.07 N/mm2


c = 0.355 N/mm2

(From SP16)



316.5 237

1.42

0.115 3.27 0.115

116 113

164

201

204

Load Diagram

1.42 223.86

23.23 0.547

13.14

156.55

293.27 S.F.Diagram


49/65

-225.287

1.34 0.75

B.M.Diagram



isolated T- beam.


bf= = 0.750 m

= 750 mm

bw= = 450 mm



Ast= 1216 mm2


0.29 %


Shear = 157 kN

v = 0.64 N/mm2

c = 0.330 N/mm2

(From SP16)




Provide Y 8 @ 250 mm = 201


50/65

SUMMARY: -






0.459375


51/65

oment

MX

1

2

orm.


52/65

kN m / metre

mm

mm

129 mm


53/65

mm2

0.16 %

mm2

mm2

0.17 %

Load per metre


54/65

mm2


55/65

Project Comments:

User ARIF Date Time 03:13

Footing Identifier =

Safe Bearing Capacity of Soil = 20 T/m2

Depth of Founding Level below Ground (Df) = 2 m

m

Weight Density of Soil & Backfill togethe = 1.8 T/m3

Load Factor for Limit State Method (LF) = 1.5 Factor

Concrete Grade (Fck) = 20 N/mm2

Steel Grade (fy) = 415 N/mm2

Column Dimensions: E_W (L1) = 0.3 m WidthColumn Dimensions: N_S (B1) = 0.23 m Width

Offset from face of column = 75 mm

Crack width = 0.3 m

LOAD CASES

Case Load (T) Soil over

MZ( @Z ) MX( @X ) Stress Actual /

P M_E-W M_N-S Factor Allowable

I 14 0 0 1 0.97

II 14 0 0 1.25 0.92

III 13 0 0 1.25 0.83

IVV

VI

VII

VIII

For SBC

Punching

L / B 0.88 Stress (E

Length - L 0.91 M E_W AREA 0.728 m Stress (NS

Width - B 0.80 M N_S Depth (be

Z_NS 0.1 m Reinf. (Be

if (P > Pp) then 'Revise Footing Size' Z_EW 0.1 m Bearing pr

Depth of Footing at Centre 550 mm Depth of Footing at Ed

Eff. Cover to Bott. Reinf. d' 75 mm de=D-d'= 475

Distances from CL of to a) Column Face, b) De from & its Distance from Edge,

Perimeter & Punching Area for Shear ECT,.

E-W N-S perimeter area, Ap

L1 (E-W) 0.3 Xf 0.15 0.115

L (E-W) 0.91 Lf 0.305 0.285

D E S I G N O F I S O L A T E D SLOPED

18-Aug-14

Moments (T.M)

ETABS NO. 10 DWG NO. C16

0.8

0

Trial Footing Size

Section Modulus

For Moment For punching shear

B=


56/65


57/65

R = Mu / b * de

- N/mm

Pt (Req)= 0.5*Fck/Fy{[1-(1-4.6*Mu/B*de^2)/Fck]^0.5}*b*de

Pt (Req) Min = 0.12%

Ast - Reinforcement to be required = Pt (req) * A * d

Ast - Reinforcement Provided

Pt (Provided) @ Efffective depth d from face of column

Allowable Shear Stress (t/m2) =0.85*sqrt(0.8*Fck)*(sqrt(1+5*b)-1)/6*b

b =0.8 * Fck / 6.89 * pt 1.00 for E_W 1.00 for N_S

Actual Shear stress (t/m2)

Bearing pressure = Pu/bD in t/m2 0.30

Permissible bearing pressure = 0.45 fck (sqrt(A1/A2)) 1.80

A1 = (min of (Lf x Bf or ( b + 4Df )x ( D + 4 Df ) 728000

A2 = b x D 69000

where sqrt(A1/A2) should not be greater than 2

Footing Size

Pedestal Dimensions: E_W = 0.30 m

Pedestal Dimensions: N_S = 0.23 m

Length - L: E_W = 0.91 m

Width - B: N_S = 0.80 m

Depth = Column face 550 mm

Footing Edge 230 (E_W)

Ast =

1 Excavation 3.10 m3

2 PCC 0.13 m3

3 RCC 0.28 m3 1 Concrete

4 Formwork 0.8 m2 2 Formwork

5 Reinforcement 8 Kgs

Total reinforcement per cft = 8 0.28 35.314 0.819724

Long Side

Bottom Reinf.

Quantities

F o o t i n g P e d e s t a


58/65


59/65

L (E-W)= 0.91 m & B (N-S) = 0.80 m

Column offset+2xEffecti

= -0.11 m2

(Area of trapaezoid) Footing base dimension

= -0.16 m2

(Area of trapaezoid)

a = 1-(1/(1+2/3*SQRT(Lpu/Bpu))) 1-(1/(1+2/3*SQRT(Bpu/Lpu)))

J=

C= Lpu/2 Bpu/2

M= a/ (0.85*J_E-W) a/ (0.85*J_N-S)

e) x 1.8

2.76

) P-edge=Ptot*(1+6*El/L)

B^2*Xf) P-face=Ptot*(1+12*El/L^2*Xf)

^2*Xd) P-d =Ptot*(1+12*El/L^2*Xd)

3+P-face/6-Pob/2}L TM

d)*0.5-Pob}L T/m

P-d M-face V@De Punch.sh P-edge P-face P-d M-face

t/m2 tm t strs t/m2 t/m2 t/m2 t/m2 tm

23.14 0.71 (2.61) 47.83 22.91 22.81 22.97 0.70

28.26 0.83 (3.22) 47.92 23.27 23.21 23.31 0.72

22.72 0.70 (2.56) 47.75 24.45 22.95 25.45 0.74

0.8 -2.56 47.92 0.74

1.2 -3.84 71.87 1.11

7.49 6.66

111.80

Depth OK

E - W N - S

[2*(De*Lpu^3)/12]+[2*(Lpu*De^3)/12]+[De*(Bp

u*Lpu^2/2))]

[2*(De*Lpu^3)/12]+[2*(Lpu*De^3)/

[(De*Lpu*Bpu^2)/2)]

W I T H N O T E N S I O N

FOR - M_E-W only FOR - M_N-S only

Depth OK


60/65

0.07 0.05

0.019 0.015

0.12 0.12

456 519

550 628

-0.48 -0.39

82.14 .

58.81

Kgs Nos. Dia Spacing (N_S) Kgs Nos. Dia

4 7 10 150 4 8 10

0 m3

2 m2

Depth OK Depth OK

OK

S u m m a r y

Short Side

l


61/65

Pedge

Pd

ce

TensionAllowed

CaseII

ce


62/65

e depth

D_os

D min

V@De

t

(3.30)

(3.36)

(3.65)

-3.30

-4.95

12]+


63/65

82.14

40.41

Spacing

150


64/65

Story Point Load FX FY FZ MX MY MZ

BASE 69 COMB1 1.26 -0.1 202.33 0.196 0.429 0.012

BASE 69 COMB2 -0.82 -0.04 165.17 0.101 -4.63 -0.03

BASE 69 COMB3 2.84 -0.12 158.55 0.213 5.317 0.049

BASE 69 COMB4 0.66 -0.96 165.68 2.329 0.389 0.046

BASE 69 COMB5 1.36 0.79 158.04 -2.015 0.298 -0.027

BASE 69 COMB6 -1.04 -0.03 197.6 0.11 -5.832 -0.034BASE 69 COMB7 3.52 -0.14 189.33 0.25 6.602 0.065

BASE 69 COMB8 0.8 -1.18 198.24 2.895 0.442 0.061

BASE 69 COMB9 1.68 1.01 188.69 -2.535 0.327 -0.03

BASE 69 COMB10 -1.54 0 120.21 0.038 -5.986 -0.04

BASE 69 COMB11 3.03 -0.11 111.95 0.178 6.448 0.059

BASE 69 COMB12 0.31 -1.14 120.86 2.823 0.288 0.055

BASE 69 COMB13 1.18 1.04 111.3 -2.607 0.174 -0.036


65/65

135 0.29 0.13

138 -3.86 0.08

132 4 0

138 0 2

132 0 -2

132 -4 0126 4 0

132 0.29 1.93

126 0 -2

Documents

Combined Isolated Footing