ISOLATED FOOTING DESIGN

FORCES DETAILS : Axial Load = P1 = 65.2 TMoment along Major axis = Mx = 0.32 T-mMoment along Minor axis = Mz = -6.0341 T-m

COLUMN DETAILS : G.LLength = ( Larger Dimension of Column ) 0.45 mWidth = ( Smaller Dimension of Column ) 0.23 m

FOOTING DETAILS :Length = L = 1.5 mWidth = B = 1.5 m 1.2Depth = D = 0.35 m

Cover to Main R/f = 0.05 mDiameter of R/f in Footing = 12 mm

0.4SOIL DETAILS :

1.7Depth of foundation below G.L = H = 1.5 m 1.50

X

MATERIAL CONSTANT :

Concrete Grade = M - 25R/f Grade = Fe - 415 1.50

1.5 Z Z

DESIGN FORCES : Axial load = P = 65.20 TSelf Weight of Footing = 1.97 T X

1.50

Total Vertical Load = 67.17 T

Moment along Major axis 0.3182 T-mMoment along Minor axis -6.0341 T-m

PRESSURE CALCULATION :

SBC = 20

FOR EARTHQUAKE CONDITION ALLOWABLE S.B.C = 1.25 x 20 = 25

P =P + Mx + MzA - Zx - Zz

29.85 + 0.57 + ### 19.69 < S.B.C SAFE

29.85 - 0.57 - ### 40.01 TENSION NOT CREATED

Density of Soil = g = T/m3

N/mm2

N/mm2

Load Factor = gf =

T/m2

T/m2

\ Pmax = T/m2

\ Pmin = T/m2

R/F CALCULATION FROM BENDING CONSIDERATION :

1500

635

1500 230

450525

40.0

19.7

MOMENT AT CRITICAL SECTION ALONG WIDTH :

M = Pmax x 0.635 x 0.635 / 2M = 3.97 T-m

Mu = 59.55 KN-m

Ast = 567.90 ( To be distributed in 1.5 m Length )

Min Req = 420 ( Ast = 0.12 x b x D )

Required Spacing of Bar = 12 # @ 195 C/C ALONG WIDTH

PROVIDE 12 # @ 150 C/C ALONG WIDTH

753.98

T/M2

T/M2

mm2

mm2

\ Ast = mm2

MOMENT AT CRITICAL SECTION ALONG LENGTH :

M = Pmax x 0.525 x 0.525 / 2M = 2.71 T-m

Mu = 40.71 KN-m

Ast = 384.16 ( To be distributed in 1.5 m Length )

Min Req = 420 ( Ast = 0.12 x b x D )

PROVIDE 12 # @ 265 C/C ALONG LENGTH

426.78

CHECK FOR ONE WAY SHEAR ALONG LENGTH :

Critical Section is at diatance of ' d ' from face of column

0.635

1.50 0.525 0.225

1.50

19.69 x 0.225

V = 4.43 T

Vub x d

=1.5 x 4.43

x 100001000 x 300

= 0.222

Pt = 100 x As = 100 x 426.78 = 0.14 Pt b x d 1000 x 300 0.15 0.28

0.2 0.33

0.28

HENCE SAFE

mm2

mm2

\ Ast = mm2

\ Shear force at critical section =

\ Actual Shear stress tv =

N / mm2

tc

\ tc = N / mm2

< tv

CHECK FOR ONE WAY SHEAR ALONG WIDTH :

Critical Section is at diatance of ' d ' from face of column

0.635

1.50 0.525

0.335

1.50

19.69 x 0.335

V = 6.60 T

Vub x d

=1.5 x 6.60

x 100001000 x 300

= 0.330

Pt =100 x As

=100 x 753.98

= 0.25b x d 1000 x 300

0.36

HENCE SAFE

\ Shear force at critical section =

\ Actual Shear stress tv =

N / mm2

\ tc = N / mm2

< tv

CHECK FOR TWO WAY SHEAR :

Critical Section is at distance of 'd/2' from face of column

1.50

0.75

1.50 0.53 d/2

d/2

19.69 x Area of Shadeded Portion

= 19.69 x 1.8525

= 36.48 T

Critical Perimeter = 2 x 0.75 + 2 x 0.53

= 2.56 m

Vub x d

=1.5 x 36.48

x 100002560.00 x 300

= 0.712

( CLAUSE 31.3.3 IS 456 : 2000 )

where,ks =

Short Side of Column = 0.23= 0.51Long Side of Column = 0.45

ks = 1.01 but not greater than 1.0

\ Shear force at Critical Section =

\ Actual Shear stress tv =

N / mm2

Allowable Shear stress = ks.tc

( 0.5+b )

b =

Where,

M - 25 = 1.25

1.25 SAFE

CHECK FOR OVERTURNING :ALONG LENGTH :

Rm Restoring Moment = 65.20 x 0.75

Rm = 48.90 T.m

Applied Moment = 0.3 T.m

F.O.S. =Restoring Moment Applied Moment

P=

48.90= 153.680.3182

> 2.2

SAFE0.75

tc = 0.25 Ö fck

tc = 0.25 Ö N/mm2

Allowable Shear stress = ks.tc = N/mm2