1 of 18
DESIGN FOR FIRE WATER TANK FOUNDATION - RING WALL
Rev.0
MATERIAL DATA
Characteristic strength of concrete
fcu
40.0
N/mm2
Characteristic strength of steel
fy
414.0
N/mm2
Unit weight of concrete
25.0
kN/m3
Elastic modulus of concrete
Ec
2.8E+04
N/mm2
Elastic modulus of steel
Es
2.0E+05
N/mm2
Clear cover
75.0
mm
SOIL DATA
The following Soil parametres considered for Design and assumed value of Allowable Bearing Capacity will be
validated with Geotechnical Investigation report and document will be updated if required
Allowable bearing capacity of soil
qall
140.0
1.25
qgross
200.20
kN/m2
kN/m3
Factor for SBC ( 1.25 for Seismic or Wind comb,otherwise 1)
Gross bearing capacity of soil
Density of soil
18.0
Co-efficient of friction between soil and wall
0.35
Factor of safety against sliding
1.5
Factor of safety against overturning
1.5
Angle of internal friction
30.0
1 - sin
Soil lateral pressure coefficient (At rest)
Ko
kN/m2
0.50
PRODUCT DATA
(Reference- Document No. xxxxxxxxxxxxxxxxxxx)
Product
Specific gravity
Water
1
Unit weight of test fluid
10
kN/m3
Unit weight of fluid for design
10.00
kN/m3
18.90
18.30
7.30
Elevation of top of ring wall
EL 101.50
Elevation of bottom of ring wall foundation
EL 99.00
Elevation of grade level
EL 100.00
0.8
STRUCTURE DIMENSIONS
1. Dimensions of tank
(Reference- Document No. xxxxxxxxxxxxxxxxxxxxx)
Outer diameter. of base ring
Diameter of tank
Height of tank
2. Geometry of ring wall & footing
Thickness of ring wall
2.50
Total height of ring wall foundation
2.50
Inner dia. of ring wall
ID
17.30
Outer dia. of ring wall
OD
18.90
Inner dia. of ring wall foundation
16.10
Outer dia. of ring wall foundation
20.10
Height of ring wall above natural grade level
1.50
Width of Ring wall
0.80
Width of footing
2.0
Thickness of footing
0.40
Height of ring wall
(Annexure)
2 of 18
3. Grade information
Finished ground level
EL 100.00
113.7
m2
4. Calculation for sectional properties of ring wall foundation
Area at base
Section modulus at base
469.1
m3
Perimeter of Tank
57.5
m3
LOAD DATA
(Reference- Document No. 3664-M3UT-5-52-0001 Sht.001)
Wempty
760
kN
Test Weight of Tank
Wtest
19950
kN
Operating weight of Tank
Wopt
19030
kN
kN
Empty weight of tank
=
1. Dead loads
Weight of Tank shell + roof
P1
553.63
Weight of ring wall
P2
2843
kN
Weight of ring wall footing
P3
1137
kN
Weight of soil over the footing on innerside
P4
1417
kN
Weight of soil over the footing on outerside
P5
662
kN
Weight of liquid portion on wall
P6
2041
kN
Weight of liquid portion on footing
P6
Total dead load at base
PD
2298
kN
P1 + P2 + P3 + P4 + P5 + P6
10951
kN
PL
316
kN
2. Live load
(1.2kN/m2 is considered)
Live load from tank roof
3. Wind Load (WL)
(Reference- Document No. 3664-M3UT-5-52-0001 Sht.001)
Horizontal shear at top of ring wall
H1
334.3
kN
Moment at top of ring wall
M1
2520.0
kN.m
137.7
kN/m
kN.m
Equivalent vertical load due to moment
Since forces due to wind are greater than seismic, the governing case for
design will be wind. Hence the following loads are considered.
Moment at base due to wind
3356
Total vertical load
PD
10951
kN
Moment
3356
kN.m
Pressure due to axial load
M
p1
P/A
p2
CHECK FOR BEARING CAPACITY
1. Case (1) - DL + WL
96
Pressure due to moment
Max. upward soil pressure
Min. upward soil pressure
f1
f2
kN/m2
M/Z
kN/m2
7
p1 + p 2
103
kN/m2
<
kN/m2
OKAY
200
p1 - p 2
89
kN/m2
OKAY
3 of 18
2. Case (2) - DL + LL + WL
Total vertical load
Moment
Pressure due to axial load
Pressure due to moment
Max. upward soil pressure
Min. upward soil pressure
PD + P L
M
p1
p2
f1
f2
11267
kN
3356
kN.m
P/A
99
M/Z
p1 + p 2
106
kN/m2
<
kN/m2
OKAY
200
p1 - p 2
92
kN/m2
OKAY
kN/m2
kN/m2
3. Case (3) - 0.9 DL + WL
Since the main resisting load is dead load, the bearing capacity needs to be
checked under minimum dead load condition with a load factor of 0.9 to
ensure that there will be no tension develops beneath the base of ring wall.
Minimum dead load
Moment
Pressure due to axial load
Pressure due to moment
Min. soil pressure
0.9 x (P1+ P2+P3+P4+P5)+P6
=
=
M
p1
p2
f
10060
kN
3356
kN.m
P/A
88
kN/m2
<
200
kN/m2
M/Z
kN/m2
7
p1 - p 2
81
kN/m2
OKAY
OKAY
CHECK FOR SLIDING
Case (1) - Tank empty condition - DL + WL
Horizontal force causing sliding
Resisting force
Factor of safety against sliding
H1
334
=
=
x Total self weight
x (P1+ P2+P3+P4+P5)
2314
=
=
=
Note : Conservatively passive resistance of soil is ignored
kN
Resisting force
Sliding force
2314
334
6.92
>
1.5
OKAY
4 of 18
CHECK FOR OVERTURNING
Case (1) - Tank Empty condition - DL + WL
Overturning moment due to wind
Restoring moment
MO
(H1 x h) + M1
334.3 x 2.5 + 2520
3356
kN.m
(P1 + P2+P3+P4+P5) x OD/2
MR =
=
=
Factor of safety against overturning
=
=
6612 x 45.3/2
53227
MR
kN.m
MO
53227
3356
15.86
>
1.5
CHECK FOR TORSION
=
qs
73.0
Length of the contact portion of content with ring wall
0.5
L
e1
Eccen. from the centre of ring wall
Lateral pressure due to earth
Pe
0.15
Ko h 2 / 2
37.8
kN
0.97
2.9 / 2 - 0.97
0.48
Koqs h
=
=
105.9
kN
1.45
2.9 / 2 - 1.45
0.000
qs b e 1
73 x 0.5 x 0.15
=
=
5.5
Pex e 2
37.8 x 0.48
=
=
18.1
Ps x e 3
105.9 x 0
0.0
Load intensity due to stored content acting
Distance from bottom of ring wall at which the force P e
acts
Eccen. from the centre of ring wall
e2
Lateral pressure due to surcharge
Ps
Distance from bottom of ring wall at which the force P s
acts
Eccen. from the centre of ring wall
e3
kN/m2
m
Considering 1 m length of ring wall,
Torsional moment due to stored content
Torsional moment due to soil lateral pressure
Torsional moment due to surcharge pressure
T1
T2
T3
kN.m
kN.m
kN.m
OKAY
5 of 18
Total torsional moment
Ts
=
(T = 1.5 x Ts)
Factored torsional moment
Shear stress due torsion
T
Vt
T 1 + T 2 +T 3
23.6
35.4
=
h2min
vt min
0.067 x SQRT( fcu )
kN.m
kN.m
2T
(hmax - hmin/3)
0.05
N/mm2
0.42
Vt
N/mm2
>
Load due to content stored
TORSION REINFORCEMENT NOT REQUIRED
acting on Ring wall
D=18.3m
e1
L=0.5m
2hw/3
T e2
Ps
hw = 2.9 m
Pe
hw/3
hw/2
Koh
t=0.8m
Longitudinal reinforcement due to additional moment
M
T( D/2-L+t/2)
35.4285((18.3 / 2 ) - 0.5 + (0.8 / 2 ))
320.6279 kN.m
Effective depth
The ratio
Lever arm
2417.5 mm
(M) / bd2fcu
0.0017144
d (0.5+(0.25 - k/0.9)^0.5)
=
(z) Max.
2296.625 mm
2296.625 mm
Reinforcement required
As
4Nos T 16
Area of steel required
0.95 d
=
Therefore the design "z" value
Provide
2412.8861
(M) / 0.95 fy z
354.96645 mm2
800 mm2
>
354.96645 mm2
DESIGN OF REINFORCEMENT
1. Horizontal reinforcement
Ring wall is subjected to lateral pressure from soil which is confined within the ring wall
and surcharge pressure due to stored content. Since the stiffness of the ring wall for
hoop tension is very high, it will yield very very less for these lateral soil pressure. Hence
the soil inside the ring wall will be in a state of rest and so at rest pressure coefficient is
used in calculating the lateral pressure of soil
Lateral soil press. due to soil fill
=
=
Surcharge due to content stored
qs
=
=
Lateral soil pressure due to surcharge
Ko h
26.1
kN/m2
qs
73.00
Ko q
kN/m2
kN/m2
OKAY
6 of 18
36.5
kN/m
7 of 18
Total pressure at bottom
Total pressure at Top
Ave Pressure
Hoop tension
Pmax
36.5 + 26.1
62.6
kN/m2
Pmin
36.5
kN/m2
Pave
(Pmax+Pmin) / 2
=
=
49.6
Pavex ID/2 x h
1072.5
Ts
Surcharge due to content stored = q
kN/m2
kN/m
D=18.3m
Koh
Koq
Koh
Ko q
Factored hoop tension
T
Ast
Area of steel required
1.5x 1072.5
1608.75
T / 0.90 x fy
kN/m
1608.75 x 1000
0.90 x 414
4318
mm2
Area of steel per face
2158.8164
mm2
Min. % of reinforcement
0.25
Min. area of steel
5000
mm2
Min. Area of steel per face
2500
mm2
3351
mm2/m
>
2500
mm2/m
OKAY
DL + LL
Provide
16
150
Area of steel provided
2. Vertical reinforcement
Vertical reinforcement is checked at two critical sections one at top of ring wall and the
other at bottom of ring wall
Forces at top of ring wall
Axial load
5754
kN
Moment
kN m
The annular section is checked with the use of charts given in Reynold's hand book
(working stress method)
Modular ratio
Es/Ec
7.1
fcr
13.3
N/mm2
Mean radius of the ring wall
9.05
Thickness of ring wall
800
mm
Ratio, (M / r2 h fcr)
0.00
Ratio, (N / r h fcr)
0.06
Ratio, (h / r)
0.09
Referring to the chart given in table 165 of Reynold's Handbook, corresponding to ratios
M / r2 h fcr and N / r h fcr for h/r = 0.10, the values of steel ratio 1 are very very less and
hence provide minimum reinforcement
8 of 18
Forces at base of ring wall
Axial load
11267
kN
Moment
3356
kN m
DL + LL
The annular section is checked with the use of charts given in Reynold's hand book
(working stress method)
Modular ratio
Mean radius of the ring wall
Thickness of ring wall
Es/Ec
7.1
fcr
13.3
N/mm2
9.05
800
mm
0.004
M / r2 h fcr
Ratio
Ratio
N / r h fcr
0.12
Ratio
h/r
0.088
Referring to the chart given in table 165 of Reynold's Handbook, corresponding to ratios
M / r2 h fcr and N / r h fcr for h/r = 0.10, the values of steel ratio 1 are very very less and
hence provide minimum reinforcement
Min. % of reinforcement
0.20 %
Min. area of steel
1600
mm2/m
Min. area of steel per face
800
mm2/m
1005
mm2/m
>
800
mm2/m
height of ring wall at notch location
1.57
effective height of ring wall
1473.00
mm
Area of steel provided per face
16
200
OKAY
CHECK BY ASSUMING SUPPORT DISCONTINUITY
By assuming 3 m length soil support discontinuity along the periphery
Moment
Ultimate moment
Mu / fcubd2
Area of Steel
(1.5 x Ms)
Ast, reqd
Mu / 0.95 y z
Ms
239.0
kN.m
Mu
358.5
kN.m
0.008
0.5 + (0.25-k/0.9)
0.741
41310^6 / (0.954140.7331473)
=
Error, Type zero in the
834.64
mm2
reinforcement provided ( 5Nos T 16)
1000 mm2
Shear
318.7
Ultimate shear
478.0
kN
Shear stress
Design Shear Strength of conc. vc
0.38
N/mm2
0.79[100 As / b d1]/0.93/1.25
0.79[0.29]/ 0.93/1.25
0.11
Allowable shear stress for min reinforcement
shear reinforcement provided (vertical bar)
kN
N/mm
0.11
N/mm2
<
T 16 @ 200
N/mm
Area of Shear Reinforcement Reqd.Asv
Svb(v-Vc) / 0.95 fy
as ==> (v-vc) < 0.4, (v-vc) = 0.4
200800(0.93-0.39) / 0.95 414
83.9796 mm
<
0.38
2
N/mm2
(402 mm2)
(402 mm2)
OKAY
9 of 18
FOOTING
Bearing pressure for Design (Ultimate state)
Design maximum bearing pressure
1.5qmax
159.34 kN/m2
159.34 kN/m2
Conservatively assuming maximum bearing pressure
(M)
28.68156
kN m
Calculation for reinforcement.
For moment Effective depth
The ratio
Lever arm
Lever arm
(z) Max.
Therefore the design "z" value
Reinforcement required
z
As
(As)Pro. in
12
0.95d
301.15
150
d (0.5+(0.25 - k/0.9)0.5)
317
(As)Min.
7.1E-009
=
=
317
mm
(M)L / bd2fcu
3.4.4.4
Part 1
mm
317
mm
(M)L / 0.95 fy z
230.0486 mm2
0.0013
520
mm
mm2
754 mm2
Min
= ( 47000/fs , 300)
Max clear spacing of bars in tension
=
Actual clear spacing provided
=
<
246.9145 mm
138
mm
246.9145 mm
OKAY
Punching shear check at column face
Column Perimeter
Shear stress
Sp
Vc
2a+2b
=
=
3600
P / (Sp * d)
0.005042 N/mm2
<
5.059644 N/mm2
OKAY
One-way shear check at d from the column face
The length
(L-h)/2
Effective shear length
600.00
mm
283.00
mm
Shear force at critical section
Shear stress
45.09379 kN
V/bd
0.142252 N/mm2
The steel ratio
100As / bd
0.24 %
The ratio
400/d
1.26
1.00
0.46 N./mm2
>
0.142252 N/mm2
The design value of 400/d
Ultimate shear capacity
vc
OKAY
10 of 18
DESIGN FOR TEMPERED WATER TANK FOUNDATION - RING WALL
Rev.0
MATERIAL DATA
Characteristic strength of concrete
fcu
40
N/mm2
Characteristic strength of steel
fy
460
N/mm2
Unit weight of concrete
25
kN/m3
Elastic modulus of concrete
Ec
28000
N/mm2
Elastic modulus of steel
Es
200000
N/mm2
Clear cover
75
mm
SOIL DATA
The following Soil parametres considered for Design and assumed value of Allowable Bearing Capacity will be
validated with Geotechnical Investigation report and document will be updated if required
Allowable bearing capacity of soil
qall
140
1.25
qgross
198.40
kN/m2
kN/m3
Factor for SBC ( 1.25 for Seismic or Wind comb,otherwise 1)
Gross bearing capacity of soil
Density of soil
18
Co-efficient of friction between soil and wall
0.35
Factor of safety against sliding
1.50
Factor of safety against overturning
1.50
Angle of internal friction
30
1 - sin
Soil lateral pressure coefficient (At rest)
Ko
kN/m2
0.50
PRODUCT DATA
(Reference- Document No. xxxxxxxxxxxxxxxxxxx)
Product
Specific gravity
Water
1.000
Unit weight of test fluid
10.000
kN/m3
Unit weight of fluid for design
10.00
kN/m3
2.275
1.800
3.000
Elevation of top of ring wall
EL 7.300
Elevation of bottom of ring wall foundation
EL 6.100
Elevation of grade level
EL 7.000
0.450
STRUCTURE DIMENSIONS
1. Dimensions of tank
(Reference- Document No. xxxxxxxxxxxxxxxxxxxxx)
Outer diameter. of base ring
Diameter of tank
Height of tank
2. Geometry of ring wall & footing
Thickness of ring wall
1.20
Total height of ring wall foundation
1.20
Inner dia. of ring wall
ID
1.375
Outer dia. of ring wall
OD
2.275
Inner dia. of ring wall foundation
1.375
Outer dia. of ring wall foundation
2.275
Height of ring wall above natural grade level
0.30
Width of Ring wall
0.45
Width of footing
0.450
Thickness of footing
0.400
Height of ring wall
(Annexure)
11 of 18
3. Grade information
Finished ground level
EL 7.000
2.6
m2
4. Calculation for sectional properties of ring wall foundation
Area at base
Section modulus at base
1.0
m3
Perimeter of Tank
5.7
m3
LOAD DATA
(Reference- Document No. xxxxxxxxxxxxxxxxxxx)
Wempty
14.00
kN
Test Weight of Tank
Wtest
244.10
kN
Operating weight of Tank
Wopt
251.10
kN
kN
Empty weight of tank
=
1. Dead loads
Weight of Tank shell + roof
P1
12.00
Weight of ring wall
P2
77
kN
Weight of ring wall footing
P3
26
kN
Weight of soil over the footing on innerside
P4
kN
Weight of soil over the footing on outerside
P5
kN
Weight of liquid portion on wall
P6
32
kN
Weight of liquid portion on footing
P6
Total dead load at base
PD
0
kN
P1 + P2 + P3 + P4 + P5 + P6
147
kN
PL
3.10
kN
2. Live load
(1.2kN/m2 is considered)
Live load from tank roof
3. Wind Load (WL)
(Reference- Document No. xxxxxxxxxxxxxxxxxxxxxxxxxxxx)
Horizontal shear at top of ring wall
H1
4.33
kN
Moment at top of ring wall
M1
6.60
kN.m
3.67
kN/m
Equivalent vertical load due to moment
4. Seismic Load (SL)
(Reference- Document No. xxxxxxxxxxxxxxxxxxxxxxxxx)
Horizontal shear at top of ring wall
H2
5.50
kN
Moment at top of ring wall
M2
8.60
kN.m
kN.m
Since forces due to seismic are greater than wind, the governing case for
design will be seismic. Hence the following loads are considered.
Moment at base due to seismic
15
Total vertical load
PD
147
kN
Moment
15
kN.m
Pressure due to axial load
M
p1
P/A
p2
CHECK FOR BEARING CAPACITY
1. Case (1) - DL + WL
57
Pressure due to moment
Max. upward soil pressure
Min. upward soil pressure
f1
f2
kN/m2
M/Z
kN/m2
15
p1 + p 2
72
kN/m2
<
kN/m2
OKAY
198
p1 - p 2
42
kN/m2
OKAY
12 of 18
2. Case (2) - DL + LL + WL
Total vertical load
PD + P L
=
=
Moment
Pressure due to axial load
Pressure due to moment
Max. upward soil pressure
Min. upward soil pressure
M
p1
p2
f1
f2
150
kN
15
kN.m
P/A
58
M/Z
15
p1 + p 2
73
kN/m2
<
kN/m2
OKAY
198
p1 - p 2
43
kN/m2
OKAY
kN/m2
kN/m2
3. Case (3) - 0.9 DL + WL
Since the main resisting load is dead load, the bearing capacity needs to be
checked under minimum dead load condition with a load factor of 0.9 to
ensure that there will be no tension develops beneath the base of ring wall.
Minimum dead load
Moment
Pressure due to axial load
Pressure due to moment
Min. soil pressure
0.9 x (P1+ P2+P3+P4+P5)+P6
=
=
M
p1
p2
f
135
kN
15
kN.m
P/A
53
kN/m2
<
198
kN/m2
M/Z
kN/m2
15
p1 - p 2
37
kN/m2
OKAY
OKAY
CHECK FOR SLIDING
Case (1) - Tank empty condition - DL + WL
Horizontal force causing sliding
Resisting force
Factor of safety against sliding
H1
=
=
x Total self weight
x (P1+ P2+P3+P4+P5)
40
kN
Resisting force
Sliding force
40
=
=
Note : Conservatively passive resistance of soil is ignored
4
9.24
>
1.5
OKAY
13 of 18
CHECK FOR OVERTURNING
Case (1) - Tank Empty condition - DL + WL
Overturning moment due to wind
Restoring moment
MO
(H1 x h) + M1
4.33 x 1.2 + 6.6
12
kN.m
(P1 + P2+P3+P4+P5) x OD/2
MR =
=
=
Factor of safety against overturning
115 x 45.3/2
79
kN.m
MR
MO
79
12
6.70
>
1.5
CHECK FOR TORSION
=
qs
30.0
Length of the contact portion of content with ring wall
0.2125
L
e1
Eccen. from the centre of ring wall
Lateral pressure due to earth
Pe
0.11875
Ko h 2 / 2
11.5
kN
0.53
1.6 / 2 - 0.53
=
=
0.27
Koqs h
24.0
0.8
1.6 / 2 - 0.8
0.000
qs b e 1
30 x 0.2125 x 0.12
=
=
0.8
Pex e 2
11.5 x 0.27
=
=
3.1
Ps x e 3
24 x 0
0.0
Load intensity due to stored content acting
Distance from bottom of ring wall at which the force P e
acts
Eccen. from the centre of ring wall
e2
Lateral pressure due to surcharge
Ps
Distance from bottom of ring wall at which the force P s
acts
Eccen. from the centre of ring wall
e3
kN/m2
m
kN
m
Considering 1 m length of ring wall,
Torsional moment due to stored content
Torsional moment due to soil lateral pressure
Torsional moment due to surcharge pressure
T1
T2
T3
kN.m
kN.m
kN.m
OKAY
14 of 18
Total torsional moment
Ts
=
(T = 1.5 x Ts)
Factored torsional moment
Shear stress due torsion
T
Vt
T 1 + T 2 +T 3
3.9
5.8
=
h2min
vt min
0.067 x SQRT( fcu )
kN.m
kN.m
2T
(hmax - hmin/3)
0.05
N/mm2
0.42
Vt
N/mm2
>
TORSION REINFORCEMENT NOT REQUIRED
Load due to content stored
acting on Ring wall
D=1.8m
L=0.2125m
e1
2hw/3
T
hw = 1.6 m
Ps
e2
Pe
hw/2
hw/3
Koh
t=0.45m
Longitudinal reinforcement due to additional moment
M
T( D/2-L+t/2)
5.793046875((1.8 / 2 ) - 0.5 + (0.45 / 2 ))
5.286155 kN.m
Effective depth
The ratio
Lever arm
1117.5 mm
(M) / bd2fcu
0.0002352
d (0.5+(0.25 - k/0.9)^0.5)
=
(z) Max.
1061.625 mm
1061.625 mm
Reinforcement required
As
4Nos T 16
Area of steel required
0.95 d
=
Therefore the design "z" value
Provide
1117.2079
(M) / 0.95 fy z
11.394292 mm2
800 mm2
>
11.394292 mm2
DESIGN OF REINFORCEMENT
1. Horizontal reinforcement
Ring wall is subjected to lateral pressure from soil which is confined within the ring wall
and surcharge pressure due to stored content. Since the stiffness of the ring wall for
hoop tension is very high, it will yield very very less for these lateral soil pressure. Hence
the soil inside the ring wall will be in a state of rest and so at rest pressure coefficient is
used in calculating the lateral pressure of soil
Lateral soil press. due to soil fill
=
=
Surcharge due to content stored
qs
=
=
Lateral soil pressure due to surcharge
Ko h
14.4
kN/m2
qs
30.00
Ko q
kN/m2
kN/m2
OKAY
15 of 18
15.0
kN/m
16 of 18
Total pressure at bottom
Total pressure at Top
Ave Pressure
Hoop tension
Pmax
15 + 14.4
29.4
kN/m2
Pmin
15.0
kN/m2
Pave
(Pmax+Pmin) / 2
=
=
22.2
Pavex ID/2 x h
18.0
1.5x 18
27
T / 0.90 x fy
Ts
kN/m2
kN/m
D=1.8m
Surcharge due to content stored = q
Koh
Ko q
Koh
Koq
Factored hoop tension
T
Ast
Area of steel required
kN/m
27 x 1000
0.90 x 460
65
mm2
Area of steel per face
32.608696
mm2
Min. % of reinforcement
0.25
Min. area of steel
1350
mm2
Min. Area of steel per face
675
mm2
1608
mm2/m
>
675
mm2/m
OKAY
DL + LL
Provide
16
150
Area of steel provided
2. Vertical reinforcement
Vertical reinforcement is checked at two critical sections one at top of ring wall and the
other at bottom of ring wall
Forces at top of ring wall
Axial load
124
kN
Moment
kN m
The annular section is checked with the use of charts given in Reynold's hand book
(working stress method)
Modular ratio
Es/Ec
7.1
fcr
13.3
N/mm2
Mean radius of the ring wall
0.91
Thickness of ring wall
450
mm
Ratio, (M / r2 h fcr)
0.00
Ratio, (N / r h fcr)
0.02
Ratio, (h / r)
0.49
Referring to the chart given in table 165 of Reynold's Handbook, corresponding to ratios
M / r2 h fcr and N / r h fcr for h/r = 0.10, the values of steel ratio 1 are very very less and
hence provide minimum reinforcement
17 of 18
Forces at base of ring wall
Axial load
150
kN
Moment
15
kN m
DL + LL
The annular section is checked with the use of charts given in Reynold's hand book
(working stress method)
Modular ratio
Mean radius of the ring wall
Thickness of ring wall
Es/Ec
7.1
fcr
13.3
N/mm2
0.9125
450
mm
0.003
M / r2 h fcr
Ratio
Ratio
N / r h fcr
0.03
Ratio
h/r
0.493
Referring to the chart given in table 165 of Reynold's Handbook, corresponding to ratios
M / r2 h fcr and N / r h fcr for h/r = 0.10, the values of steel ratio 1 are very very less and
hence provide minimum reinforcement
Min. % of reinforcement
0.20 %
Min. area of steel
900
mm2/m
Min. area of steel per face
450
mm2/m
1005
mm2/m
>
450
mm2/m
height of ring wall at notch location
1.57
effective height of ring wall
1473.00
mm
Area of steel provided per face
16
200
OKAY
CHECK BY ASSUMING SUPPORT DISCONTINUITY
By assuming 3 m length soil support discontinuity along the periphery
Moment
Ultimate moment
Mu / fcubd2
Area of Steel
(1.5 x Ms)
Ast, reqd
Mu / 0.95 y z
Ms
37.1
kN.m
Mu
55.7
kN.m
0.001
0.5 + (0.25-k/0.9)
0.749
41310^6 / (0.954140.7331473)
=
Error, Type zero in the
128.42
mm2
reinforcement provided ( 5Nos T 16)
1000 mm2
Shear
49.5
Ultimate shear
74.3
kN
Shear stress
Design Shear Strength of conc. vc
0.11
N/mm2
0.79[100 As / b d1]/0.93/1.25
0.79[0.29]/ 0.93/1.25
0.04
Allowable shear stress for min reinforcement
shear reinforcement provided (vertical bar)
kN
N/mm
0.04
N/mm2
<
T 16 @ 200
N/mm
Area of Shear Reinforcement Reqd.Asv
Svb(v-Vc) / 0.95 fy
as ==> (v-vc) < 0.4, (v-vc) = 0.4
200800(0.93-0.39) / 0.95 414
11.9865 mm
<
0.11
2
N/mm2
(402 mm2)
(402 mm2)
OKAY
18 of 18
FOOTING
Bearing pressure for Design (Ultimate state)
Design maximum bearing pressure
1.5qmax
110.02 kN/m2
110.02 kN/m2
Conservatively assuming maximum bearing pressure
(M)
kN m
Calculation for reinforcement.
For moment Effective depth
The ratio
Lever arm
Lever arm
(z) Max.
Therefore the design "z" value
Reinforcement required
z
As
12
d (0.5+(0.25 - k/0.9)0.5)
317
0.95d
301.15
150
(As)Min.
=
(As)Pro. in
317
mm
(M)L / bd2fcu
3.4.4.4
Part 1
mm
317
mm
(M)L / 0.95 fy z
0.0013
520
mm
mm2
mm2
754 mm2
Min
= ( 47000/fs , 300)
Max clear spacing of bars in tension
=
Actual clear spacing provided
=
<
222.223 mm
138
mm
222.223 mm
OKAY
Punching shear check at column face
Column Perimeter
Shear stress
Sp
Vc
2a+2b
=
=
2900
P / (Sp * d)
0.000135 N/mm2
<
5.059644 N/mm2
OKAY
One-way shear check at d from the column face
The length
(L-h)/2
Effective shear length
0.00
mm
-317.00 m m
-34.8778 kN
Shear force at critical section
Shear stress
V/bd
-0.11002 N/mm2
The steel ratio
100As / bd
0.24 %
The ratio
400/d
1.26
1.00
0.46 N./mm2
>
-0.11002 N/mm2
The design value of 400/d
Ultimate shear capacity
vc
OKAY
