DESIGN OF FOUNDATION:
1.0 Footing Data
Unit Weight of Concrete
Grade of Concrete
Net SBC
Increament factor for BC
Concrete cover
25.00
30.00
200
1.00
75.00
SBCnet
fbc
Depth of foundation below ground level ,dfgl
Pedestal height above Ground level
Tenion load
Unit Weight of soil
Angle of internal friction
Coeffcient of friction
FOS against Overturning
FOS against sliding
Load acting at(Top
of Pedestal/Bottom of Footing):
Axial
Load
Load,
Shear,
Moment,
case/Node
Py(kN) Shear, Fx(kN)
Fz(kN)
Mx(kNm)
number
2.769
2.753
0.2
0
D.L+W.L
Gross SBC
=
fbc x SBCnet + γs x dfgl
Moment,
Mz(kNm)
2.355
=
2
=
217 kN/m
2.77
0.20
1.00
0.76
2.0 Vertical load acting at bottom of foundation
Axial Load
Weight of Pedestal
Area of foundation ( Provided )
Load due to soil
Py
Wp
A
Ws
Lp x Bp x (Hp) x 25
L*B
γs*(dfgl - D)*(A - (Lp x Bp))
=
=
=
=
kN
kN
m2
kN
Weight of footing
Wf
A*D*25
=
22.50 kN
Total Vertical Load
Pv
Py+Wp+Ws+Wf+Wgs+Wll
=
26.22 kN
3.0 Moment acting at bottom of foundation(about x-axis)
Moment
Moment due to lateral force
Moment due to eccentricity (ez)
Mx
Mlfx
Mecc
Fz * dforc
(Py+Wp)*ez
=
=
=
0
0.19
0.00
kNm
kNm
kNm
Moment acting at bottom of foundation
Mxx
Mx+Mlfx+Mecc
=
0.19
kNm
Mxx/Pv
=
0.007
m
Eccentricity along Z-Direction from cg of Footing, ez'
<
B/6
4.0 Moment acting at bottom of foundation(about z-axis)
Moment
Moment due to lateral force Fx
Moment due to eccentricity (ex)
Mz
Mlfz
Mecc
Fx * dforc
(Py+Wp)*ex
=
=
=
2.355
2.61535
0.00
kNm
kNm
kNm
Moment acting at bottom of foundation
Mzz
Mz+Mlfz+Mecc
=
4.97
kNm
Mzz/Pv
=
0.190
m
Eccentricity along X-Direction from cg of Footing, ex'
>
L/6
5.0 Bearing Pressure Calculation:Eccentricity along X-Direction from cg of Footing, ex'
Eccentricity along Z-Direction from cg of Footing, ez'
Teng Value
k
Mzz/Pv
Mxx/Pv
=
=
0.190
0.007
=
2.199
m
m
Maximum Bearing Pressure
Minimum Bearing Pressure
fmax
fmin
kPv/A
Pv/A(1-6ex'/L-6ez'/B)
Bearing capacity Ratio
BCR
fmax/Gross SBC
2
27.36 kN/m
2
25.08 kN/m
=
=
=
Safe
0.13
6.0 Check for Stability:X-Direction
Overturning Moment
Restoring Moment
Stability Ratio
Mo
Mr=Pv x L/2
Mr/Mo
=
=
=
0.19 kNm
13.11 kNm
69.01
Z-Direction
Pv x B/2
=
=
=
4.97 kNm
13.1121 kNm
2.64
>2 Safe
>2 Safe
7.0 Check for Sliding:X-Direction
Sliding Force
Resisting Force
Sliding Ratio
Hs
Hr = µPv
Hs/Hr
=
=
=
Z-Direction
2.753 kN
13.11 kN
4.76
>1.5 Safe
=
=
=
0.2 kN
13.1121 kN
65.5603
>1.5 Safe
8.0 DESIGN FORCE CALCULATIONS:8.1 X-Direction:Pressure variation :Maximum Pressure
Minimum Pressure
Design Moment:Distance from left edge to face of pedestal
Distance from right edge to face of pedestal
Moment at west face of pedestal
Moment at east face of pedestal
Design Moment
Mxu
One way Shear:Effective Depth
Pv/A(1+6ex'/L)
Pv/A(1-6ex'/L)
27.36*0.325*1000*0.325/2
27.36*0.275*1000*0.275/2
dx
Distance from left edge to d distance from west face of pedestal
Distance from right edge to d distance from east face of pedestal
Shear at d distance from west face of pedestal
27.36*0
Shear at d distance from east face of pedestal
27.36*0
Design Shear at d from face of pedestal
Vxu
Max Vx
Shear Stress at critical section
As per Clause 3.4.5.8 of BS 8110 Part1,
Alllowable Shear Strength of concrete
=
=
2
27.36 kN/m
2
25.08 kN/m
=
=
=
=
=
0.325
0.275
1.45
1.03
1.45
=
817.00
=
=
=
=
=
=
0.8170
0.000
0.000
0.00
0.00
0.00
m
m
kNm/m
kNm/m
kNm/m
m
m
m
kN/m
kN/m
kN/m
2
=
9 Z-Direction:Pressure Variation:Maximum Pressure
Minimum Pressure
Design Moment:Distance from top edge to face of pedestal
Distance from bottom edge to face of pedestal
Moment at north face of pedestal
Moment at south face of pedestal
Design Moment
Mzu
10 Punching Shear Force:At face of the pedestal
Critical section of at a distance 2d from face of footing
Critical perimeter
A
B
Area with the perimeter
=
=
=
=
2A + 2B
1167.000
1267.000
4868.00
-478589.0000
8.38E+06 mm^2
40.460
kN
mm
Punching shear force
VEd
=
=
=
Shear Stress
d
vRd,c
=
=
817
0.01
=
0.8 Roof of Fck
=
4.38
(As Per Cl 3.7.7.2 of BS 8110 : Part 1:1997, max shear strength is max of
0.8(fcu)1/2 and 5N/mm2)
mm
N/mm2
N/mm
2
11 Design of Bottom Reinforcement:Thickness of footing
Clear Bottom cover
Clear Top cover
D
Cb
Ct
=
=
=
Characteristic strength of concrete
fck
=
30 N/mm2
Characteristic strength of steel
fy
=
500 N/mm2
Effective Thickness of Footing
=
900 mm
75 mm
75 mm
817.00 mm
Mx = Base Pressure * Width of Footing * Cantilever projection
Mx =
1.223
kN.m
K
K'
Minimum Percentage of Steel
Provide Reinforcement
No of Rod Required
Provide number of Reinforcement
Provide Area of Steel
Provide
=
M / Fck*b*d^2
=
0.000
=
0.156
K
<
K'
(No need Compression Reinforcement)
Z
=
d*(0.5+SQT (0.25-k/0.9)
Z
=
817
mm
0.95*d =
776.15
mm
As
=
3.62
mm^2
=
0.13 %
=
1062.1 mm^2
=
14 mm
=
10.58104771
=
5.6
=
1134.093333 mm^2
14.00 mm Dia @
150.00 mm both ways
12 Check Uplift:
Tension in Pedestal
=
Total Vertical load in Footing =
Factor of safety