DESIGN OF RCC CHIMNEY

DATA :
DESIGN CODE : IS 4998 -(PART-1) :1992
IS 875 -(PART-3) :1987
LOCATION :

HYDERABAD

HEIGHT OF ABOVE GROUND=

HEIGHT BELOW GROUND =

76
4

M
M

BASE DIAMETER =Db=

5
M
TOP DIAMETER =Dt=
4
M
THICKNESS AT BASE =Tb=
0.4
M
THICKNESS AT TOP =Tt=
0.2
M
THICKNESS OF LINING =
0.1
M
DENSITY OF LINING =
2
T/M^3
SPACING OF LINING SUPPORT BRACKETS =
2
SIZE OF LINING SUPPORT BRACKETS =
0.3
PERCENT.OF VERTICAL STEEL =
1

M
0.3

GRADE OF CONCRETE =Fck=

25
ALLOWABLE COMPRESSIVE STRESS IN CONCETE =
6
ALLOW. BENDING COMPRE. STRESS IN CONCRETE = 8.5
ALLOWABLE TENSILE STRESS IN CONCRETE =
0.9
MODULAR RATIO =m= 10.98039
K=
0.289
J=
0.904
Q=

MXM

*BxD

N/SQ.MM
N/SQ.MM
N/SQ.MM
1.1084

Sst =

1. DEAD LOAD & SECTIONAL PROPERTIES

Hx = HEIGHT FROM TOP = n x H

Dx = INNER DIAMETER AT HEIGHT Hx
Tx = THICKNESS AT Hx
Ax1 = CROSS SECTIONAL AREA OF CONCRETE AT HEIGHT Hx
Ax2 = EQUVIVALENT CROSS SECTIONAL AREA OF STEEL AT HEIGHT Hx =(m-1)*Ax1*(n/100)
Wwx = WEIGHT OF WALL AT Hx
Wl = WEIGHT OF LINING AT Hx
Ts = EQUIVALENT THICKNESS OF STEEL REINFORCEMENT AS RING AT CENTRE OF CHIMNEY WALL = As
Ie = EQUIVALENT MOMENT OF INERTIA
CALCULATION OF LOADS, SECTIONAL AREA , INERTIA AND STRESSES
Hx

0.000
0.100
0.200
0.300

Hx

Dx

Tx

Wwx

Wl

Wwx+Wl

Ax1

Ax2

Ax1+Ax2

SQ.M

SQ.M

SQ.M

0.000
8.000
16.000
24.000

4.000
4.100
4.200
4.300

0.200
0.220
0.240
0.260

56.217
119.446
189.915

21.416
43.435
66.057

77.63
162.88
255.97

2.986
3.348
3.725

0.298
0.334
0.372

3.284
3.682
4.097

0.400
0.500
0.600
0.700
0.800
0.900
1.000

32.000
40.000
48.000
56.000
64.000
72.000
80.000

4.400
4.500
4.600
4.700
4.800
4.900
5.000

0.280
0.300
0.320
0.340
0.360
0.380
0.400

267.849
353.475
447.019
548.706
658.764
777.419
904.896

89.283 357.13
113.112 466.59
137.544 584.56
162.580 711.29
188.218 846.98
214.460 991.88
241.306 1146.20

4.117
4.524
4.947
5.384
5.837
6.304
6.787

0.411
0.452
0.494
0.537
0.583
0.629
0.677

4.528
4.976
5.440
5.921
6.419
6.933
7.464

2. DEAD LOAD + WIND LOAD

STATIC (ALONG WIND LOAD) CONDITIOIN
K1,K2,K3 FROM IS:875 -PART -III -(1987)
Vb = DESIGN WIND SPEED , M/SEC
Pz=DESIGN WIND PRESSURE = 0.6 (K1*K2*K3*Vb)^2 N/SQ.M
Dxt = Dx + Tx
e = ECCENTRICITY OF LOAD
E-MAX = MAX. ALLOWABLE ECCENTRICITY FOR NO TENSION CONDITION
THETA=NEUTRAL AXIS ANGLE
e(THETA) = ECCENTRICITY DUE TO ANGLE THETA
HEIGHT / DIAMETER = 15.83333
* REFER TABLE-23 IS:875(PART-3)-1987
* IS 4998 -(PART-1) :1992 CLAUSE:5.3

SHELL ALONE CASE WITHOUT LOADING IS CONSIDERED

CALCULATION OF WIND SHEAR , MOMENT AND STRESSES

Hx

Hx

K1

K2

K3

Vb

Pz

SHAPE

WIND

TOTAL

T/SQ.M

FACTOR

PRES.

LOAD(T)

0.096
0.096
0.096
0.096
0.096
0.096
0.096
0.096
0.096
0.096
0.096

0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700

0.067
0.067
0.067
0.067
0.067
0.067
0.067
0.067
0.067
0.067
0.067

Hsx

0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00

0.00
8.00
16.00
24.00
32.00
40.00
48.00
56.00
64.00
72.00
80.00

1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00

1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00

1.00
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

40.000
40.000
40.000
40.000
40.000
40.000
40.000
40.000
40.000
40.000
40.000

CALCULATION OF STRESS IN HOOP REINFORCEMENT

WIND SHEAR AT SECTION X = Hx
SPACING OF HOOP BARS =Sh
DIA . OF BAR = Db
AREA OF BAR = At
MEAN DIA. AT SECTION X = Dx-M
DISTANCE BETWEEN RFT. ON BOTH FACES =d= 0.8 * MEAN DIA. OF CHIMNEY
STRESS IN STEEL = Hsx. Sh / 1.6. At .d

2.403
4.957
7.661
10.515
13.521
16.676
19.983
23.439
27.047
30.804

CIRCUMFERENTIAL EFFECT DUE TO WIND

EXTERNAL AND INTERNAL RING MOMENTS=Me/Mi =0.33 . Pz. Rm^2
WIND PRESSURE AT HEIGHT X FROM TOP =Pzx
MEAN RADIUS OF SHEEL AT HEIGHT X FROM TOP = Rm
Hx

Hx

Hsx

SIZE OF

AREA OF

SPACING

MEAN

(T)

BAR

BAR(At)

OF BARS

DIA.

(MM)

(MM)

(MM)

STRESS
IN STEEL

RING
MOM.
T-M

0.00
0.00
0.10
8.00
2.403
8.0
50.272
200
4320
0.20
16.00 4.957
8.0
50.272
200
4440
0.30
24.00 7.661
8.0
50.272
200
4560
0.40
32.00 10.515
8.0
50.272
200
4680
0.50
40.00 13.521
8.0
50.272
200
4800
0.60
48.00 16.676
8.0
50.272
200
4920
0.70
56.00 19.983
8.0
50.272
200
5040
0.80
64.00 23.439
8.0
50.272
200
5160
0.90
72.00 27.047
8.0
50.272
200
5280
1.00
80.00 30.804
8.0
50.272
200
5400
MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

13.83
0.148
27.76
0.156
41.77
0.165
55.87
0.173
70.04
0.182
84.28
0.192
98.58
0.201
112.95
0.211
127.37
0.221
141.84
0.231
230 N/SQ.MM

3. DEAD LOAD +EARTH QUAKE LOAD

TOTAL WT. OF CHIMNEY =Wt=
1146.20 T
HEIGHT ABOVE BASE =h'=
80 M
MODULUS OF ELASTICITYOF CONCRET=E=
1.91E+06 N/SQ.M =
AREA OF C/S AT BASE=A = 6.787 SQ.M
RADIUS OF GYRATION AT BASE =Rg=1.9989 M
HEIGHT / RADIUS OF GYRATION =K= 40.02 M

FOR K=
30
FOR K=
35
FOR K = 40.02

CT
56
65
74.04

1.9E+06 T/SQ.M

CV
1.350
1.390
1.430

NATURAL PERIOD OF VIBRATION =

5.18 SECS
SOIL FOUNDATION SYSTEM =B= 1
IMPORTANCE FACTOR =1.5
BASIC HORIZONTAL SEISMIC COEFF.=
0.02
HORIZONTAL SEISMIC COEFF= 0.03
CG OF TOWER FROM BASE
41.830
=
M
SHELL ALONE CASE WITHOUT LOADING IS CONSIDERED
Hx

0.00
0.10
0.20
0.30

Hx

SHEAR

MOMENT

ECCTY.

ECCTY.

THETA

T-M

e(M)

E-MAX(M)

DEG

=M/W

NO TEN.

4.856
3.239
2.514

1.022
1.047
1.073

0.00
8.00
16.00
24.00

0.00
7.88
15.11
21.67

0.000
272.969
386.876
477.357

98.000
108.000
100.000

* IS 4998 -(PART-1) :1992 CLAUSE:5.3

ECCTY. MAX.CONC.MAX.STEEL.
e(THETA)

2.480
3.589
2.774

STRESS

STRESS

N/SQ.MM

N/SQ.MM

0.658
1.447
1.830

9.581
30.148
28.585

0.40
0.50
0.60
0.70
0.80
0.90
1.00

32.00
40.00
48.00
56.00
64.00
72.00
80.00

27.58 560.552
32.83 646.208
37.41 743.059
41.34 860.197
44.61 1007.573
47.23 1196.221
49.18 1438.371

2.093
1.828
1.662
1.568
1.529
1.539
1.590

1.098
1.124
1.150
1.176
1.201
1.227
1.253

92.000
85.000
80.000
75.000
70.000
70.000
70.000

2.310
2.052
1.929
1.832
1.754
1.795
1.836

2.111
2.350
2.589
2.793
2.970
3.246
3.511

24.889
21.691
20.042
18.079
16.007
17.494
18.920

4. DEAD LOAD + TEMPERATURE LOADS

COEFFICIENT OF EXPANSION STEEL/CONCRETE

1.10E-05
=A=/DEGREE
CLEAR COVER TO REINFORCEMENT = 50 MM
COVER / DEPTH RATIO =COVER
a=
/ EFEECTIVE DEPTH AT THAT SECTION
ELASTIC MODULUS OF STEEL =Es=2.10E+07 T/SQ.M =
2.10E+05 N/SQ.MM
ELASTIC MODULUS OF CONCRETE=Ec=
1.91E+06 T/SQ.M =
1.91E+04 N/SQ.MM
TEMPERATURE OF FLUME =90
DEGREE
AMBIENT TEMPERATURE= 15
DEGREE
TEMP. GRADIENT= T=
75
DEGREE
K=NEUTARAL AXIS DEPTH CONSTANT AT TEMPERATURE STRESS CONDN.= -mp+SQRT(2mpaa+p^2+m^2)
K'=NEUTARAL AXIS DEPTH CONSTANT AT TEMPERATURE+(OTHER LOAD) STRESS CONDN.
Hx

Hx
M

STRESS

a=

MAX.CONC.MAX.STEEL.

S(Wwx+Wl)
COVER/EFF.DEPTH

K'

STRESS

STRESS

N/SQ.MM

N/SQ.MM

* ADJUST K' VALUE UNTIL BALANCE A

EVALUATION OF K'

0.00
0.00
0.000
0.10
8.00
0.236
0.773
0.800
12.623
-4.892
0.773
0.20
16.00 0.442
0.783
0.750
11.834
5.476
0.783
0.30
24.00 0.625
0.808
0.750
11.834
9.281
0.808
0.40
32.00 0.789
0.821
0.790
12.465
5.237
0.821
0.50
40.00 0.938
0.833
0.760
11.991 11.587
0.833
0.60
48.00 1.074
0.844
0.700
11.045 20.662
0.844
0.70
56.00 1.201
0.853
0.800
12.623
8.603
0.853
0.80
64.00 1.319
0.861
0.800
12.623
9.836
0.861
0.90
72.00 1.431
0.868
0.800
12.623 10.920
0.868
1.00
80.00 1.536
0.875
0.800
12.623 11.880
0.875
MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND
11.305
LOAD=N/SQ.MM

0.8
0.7
0.75
0.79
0.76
0.7
0.8
0.8
0.8
0.8

0.64391
1.44366
1.87461
2.2205
2.79165
3.60881
3.3638
3.70561
4.02803
4.33375

5. DEAD LOAD + WIND LOAD +TEMPERATURE LOADS

5.A. COMPRESSION ZONE -LEEWARD SIDE
THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD
Hx

Hx
M

STRESS

a=

MAX.CONC.MAX.STEEL.

S(Wwx+Wl)
COVER/EFF.DEPTH

K'

+WINDLOAD

0.00
0.10
0.20
0.30
0.40

0.00
8.00
16.00
24.00
32.00

0.440
0.833
1.186
1.652

0.773
0.792
0.808
0.821

0.001
0.750
0.445
0.500

* ADJUST K' VALUE UNTIL BALANCE APPRO

EVALUATION OF K'
LHS
0.173
0.773
0.001 -0.00571
6.839
0.792
0.420 8.12045
34.620
0.808
0.445 9.80601
33.897
0.821
0.500 10.1247

STRESS

STRESS

N/SQ.MM

N/SQ.MM

0.016
11.834
7.021
7.889

0.50
0.60
0.70
0.80
0.90
1.00

40.00
48.00
56.00
64.00
72.00
80.00

2.249
2.729
3.195
3.622
3.912
3.177

0.833
0.844
0.853
0.861
0.868
0.875

0.550
0.580
0.620
0.660
0.680
0.707

8.678
9.151
9.782
10.414
10.729
11.155

32.398
31.411
29.335
26.705
25.561
23.518

0.833
0.844
0.853
0.861
0.868
0.875

0.550
0.580
0.620
0.660
0.680
0.707

11.3259
12.5025
13.0766
13.4347
13.899
10.6729

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND

11.305
LOAD=N/SQ.MM
5.B. TENSION ZONE- WINDWARD SIDE
THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD
Hx

Hx
M

STRESS

a=

MAX.CONC.MAX.STEEL.

S(Wwx+Wl)
COVER/EFF.DEPTH

K'

+WINDLOAD

0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00

0.00
8.00
16.00
24.00
32.00
40.00
48.00
56.00
64.00
72.00
80.00

0.440
0.833
1.186
1.652
2.249
2.729
3.195
3.622
3.912
3.177

0.773
0.792
0.808
0.821
0.833
0.844
0.853
0.861
0.868
0.875

0.001
0.750
0.445
0.500
0.550
0.580
0.620
0.660
0.680
0.120

STRESS

STRESS

N/SQ.MM

N/SQ.MM

0.016
11.834
7.021
7.889
8.678
9.151
9.782
10.414
10.729
1.893

0.173
6.839
34.620
33.897
32.398
31.411
29.335
26.705
25.561
130.804

* ADJUST K' VALUE UNTIL BALANCE APPRO

EVALUATION OF K'
LHS
0.773
0.001
0.00
0.792
0.420
0.01
0.808
0.445
0.00
0.821
0.500
0.00
0.833
0.550
0.02
0.844
0.580
0.03
0.853
0.620
0.06
0.861
0.660
0.09
0.868
0.680
0.11
0.875
0.120
0.05

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND

11.305
LOAD=N/SQ.MM
5.C. NEUTRAL AXIS
THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD
Hx

Hx
M

STRESS

a=

MAX.CONC.MAX.STEEL.

S(Wwx+Wl)
COVER/EFF.DEPTH

K'

+WINDLOAD

0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00

0.00
8.00
16.00
24.00
32.00
40.00
48.00
56.00
64.00
72.00
80.00

0.440
0.833
1.186
1.652
2.249
2.729
3.195
3.622
3.912
3.177

0.773
0.792
0.808
0.821
0.833
0.844
0.853
0.861
0.868
0.875

0.317
0.750
0.325
0.329
0.332
0.334
0.337
0.339
0.340
0.342

STRESS

STRESS

N/SQ.MM

N/SQ.MM

4.994
11.834
5.135
5.189
5.236
5.277
5.313
5.344
5.372
5.398

32.375
6.839
33.664
34.166
34.598
34.975
35.306
35.600
35.861
92.326

EVALUATION OF K'
0.773
0.792
0.808
0.821
0.833
0.844
0.853
0.861
0.868
0.875

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND

11.305
LOAD=N/SQ.MM

0.317
0.321
0.325
0.329
0.332
0.334
0.337
0.339
0.340
0.342

CALCULATION OF STRESS IN HOOP REINFORCEMENT

p=% HOOP REI9NFORCEMENT=At / SPACING x THICKNESS OF SHELL
K'=SQRT(2.m.p.a + p^2. M^2)-p.m
STRESS IN CONCRETE = Sc
STRESS IN STEEL =Sc = m . Sc. (a-K')/K'
Ss + m. Sc = Es. A. T .a
Sc(T) = TOTAL STRESS IN STEEL = STRESS DUE TO SHEAR + STRESS DUE TO TEMP
Hx

0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00

Hx

Hsx

SIZE OF

AREA OF

SPACING

MEAN

(T)

BAR

BAR(At)

OF BARS

DIA.

(MM)

(SQ.MM)

(MM)

(MM)

10
10
10
10
10
10
10
10
10
10

78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55

200
200
200
200
200
200
200
200
200
200

4320
4440
4560
4680
4800
4920
5040
5160
5280
5400

0.00
8.00
16.00
24.00
32.00
40.00
48.00
56.00
64.00
72.00
80.00

0.000
2.403
4.957
7.661
10.515
13.521
16.676
19.983
23.439
27.047
30.804

% STEEL STRESS IN STRESS IN

(p)

CONCERET

0.00179
0.00164
0.00151
0.00140
0.00131
0.00123
0.00116
0.00109
0.00103
0.00098

2.450
2.400
2.300
2.300
2.200
2.200
2.100
2.100
2.050
2.000

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

230 N/SQ.MM
DESIGN OF FOUNDATION
ADOPT CIRCULAR RAFT FOR FOUNDATION
DENSITY OF SOIL =
1.8
DEPTH OF FOUNDATION =
SBC OF SOIL =
20
THICKNESS OF RAFT=
1000

T/Cu.M
4
M
T/SQ.M
MM

LOADS & MOMENTS

PROJECTION OF RAFT BEYOND WALL =
DIAMETER OF RAFT =
10.50
M
AREA OF RAFT =
86.60
SQ.M
SECTION MODULUS =
113.66
Cu.M
SELF WEIGHT OF CHIMNEY =
WEIGHT OF LININING =
WEIGHT OF FOUNDATION =
WEIGHT OF EARTH =
TOTAL LOAD =

904.896
241.306
171.930
482.140
1800.272

2.75

T
T
T
T
T

* 15 % OF TOTAL WEIGHT

A. SELF WEIGHT OF CHIMNEY + WIND LOAD

CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED

STEEL

(N/SQ.MM) (N/SQ.MM)

120.569
138.969
154.399
174.266
188.576
207.897
221.257
240.140
255.803
271.186

TOTAL LOAD =
1558.966
T
MOMENT DUE TO WIND =
1232.18
MAX. SOIL PRES. =
MIN. SOIL PRES. =
DIA .OF SHAFT=2b=
DIA.OF RAFT SLAB=2a=

28.84
7.16

T-M

T/SQ.M
T/SQ.M

5.8 M
10.50 M

* P/A +M/Z
*P/A-M/Z
b=
a=

2.9 M
5.25 M

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =

70.8959 T-M
12.8015 T-M

B. SELF WEIGHT OF CHIMNEY + LINING WIGHT + EARTHQUAKE LOAD

TOTAL LOAD =
1800.272
T
MOMENT DUE TO EARTH QUA. = 1438.37
MAX. SOIL PRES. =
MIN. SOIL PRES. =
DIA .OF SHAFT=2b=
DIA.OF RAFT SLAB=2a=

33.44
8.13

T-M

T/SQ.M
T/SQ.M

5.8 M
10.50 M

* P/A +M/Z
*P/A-M/Z
b=
a=

2.9 M
5.25 M

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =
DESIGN RADIAL BM AT CENTRE OF RAFT =
DESIGN RADIAL BM AT FACE OF SHAFT =
DEPTH OF FOUNDATION REQUIRED =
DEPTH OF FOUNDATION ADOPTED =
CLEAR COVER =
50 MM
SIZE OF BAR =
25 MM
EFFECTIVE DEPTH =
937.5 MM
MIN. AREA OF STEEL REQUIRED/FACE =

81.655 T-M
14.2943 T-M
81.655 T-M
14.2943 T-M
858.308 MM
1000 MM

600 SQ.MM

AREA OF STEEL FOR RADIAL BM AT CENTRE OF RAFT =

SIZE OF BAR =
25 MM
AREA OF BAR = 490.94 SQ.MM
NO. OF BARS = 8.5327
SPACING OF BARS =
117.1955 MM

4189.046 SQ.MM

AREA OF STEEL FOR RADIAL BM AT FACE OF SHAFT =

SIZE OF BAR =
12 MM
AREA OF BAR = 113.11 SQ.MM
NO. OF BARS = 6.4832
SPACING OF BARS =
154.2457 MM

733.3237 SQ.MM

PROVIDE 20 MM BARS AT 100 MM C/C IN RADIAL DIRECTION ON BOTH THE FACES

MIN. AREA OF STEEL IN RAFT /FACE =

600 SQ.MM

SIZE OF BAR =
12 MM
AREA OF BAR = 113.11 SQ.MM
NO. OF BARS = 5.3045
SPACING OF BARS =
188.52 MM
PROVIDE 12 MM BARS AT 175 MM C/C IN CICUMFERENTIAL DIRECTION ON BOTH THE FACES

CHECK FOR STABILITY

A. SELF WEIGHT OF CHIMNEY + WIND LOAD
CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED
TOTAL VERTICAL LOAD =
1558.97
TOTAL HORIZONTAL LOAD =
30.804
MOMENT DUE TO WIND =
1232.18
RESISTING MOMENT =
8184.57 T-M

T
T
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

FACTOR OF SAFETY AGAINST SLIDING =

30.3651 >1.5

6.64 >1.5

SAFE

SAFE

B. SELF WEIGHT OF CHIMNEY + WEIGHT OF LINING + EARTH QUAKE LOAD

TOTAL VERTICAL LOAD =
1800.27
TOTAL HORIZONTAL LOAD =
49.178
MOMENT DUE TO EARTH QUA. = 1438.37
RESISTING MOMENT =
9451.43 T-M

T
T
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

FACTOR OF SAFETY AGAINST SLIDING =

21.9643 >1.5

6.57 >1.5
SAFE

SAFE

230 N/SQ.MM

E OF CHIMNEY WALL = As / 2.PAI. R

S(Wwx)

S(Wwx+Wl)

Ts

Ie

M^4

MAX.CONC. MAX.CONC.
STRESS

STRESS

0.002
0.002
0.002

7.616
9.023
10.592

0.171
0.324
0.464

0.236
0.442
0.625

0.003
0.003
0.003
0.003
0.003
0.003
0.004

12.335
14.263
16.389
18.724
21.282
24.075
27.117

WIND
MOMENT
(T-M)

0.592
0.710
0.822
0.927
1.026
1.121
1.212

0.789
0.938
1.074
1.201
1.319
1.431
1.536

ECCTY.

ECCTY.

THETA

e(M)

E-MAX(M)

DEG

=M/W

ECCTY. MAX.CONC.MAX.STEEL.*
e(THETA) STRESS

NO.TENSION
(T)

ADJUST THETA VALUES UNTIL e AND e(THETA) MA

STRESS

N/SQ.MM N/SQ.MM

THETA

SIN(2xT)

SIN(T)

COS(T)

0.102
0.125
0.133
0.250
0.173
0.125
0.085
0.060
0.069
0.235

0.208
0.259
0.276
0.707
0.927
0.966
0.985
0.993
0.990
0.574

0.978
0.966
0.961
0.707
0.374
0.258
0.173
0.121
0.139
0.819

RAD.

9.612
39.653
91.93
168.25
270.41
400.23
559.51
750.06
973.68
1232.18

0.171
0.332
0.484
0.628
0.765
0.895
1.020
1.139
1.252
1.362

1.054
1.079
1.105
1.130
1.156
1.181
1.207
1.232
1.258
1.284

12.00
15.00
16.00
45.00
68.00
75.00
80.00
83.00
82.00
35.00

1.053
1.081
1.110
1.261
1.592
1.788
1.976
2.128
2.140
1.377

0.375
0.715
1.025
1.454
2.022
2.476
2.921
3.329
3.603
2.854

0.046
0.136
0.222
2.743
10.112
16.027
22.607
28.647
29.930
3.118

0.210
0.262
0.279
0.786
1.187
1.310
1.397
1.449
1.432
0.611

1) :1992 CLAUSE:5.3
MAX.STEEL.

* ADJUST THETA VALUES UNTIL e AND e(THETA) MATCH

THETA

1.711
1.886
1.746

SIN(2xT)

-0.069
-0.147
-0.086

SIN(T)

0.990
0.951
0.985

COS(T)

-0.140
-0.310
-0.174

1.606
1.484
1.397
1.310
1.222
1.222
1.222

-0.018
0.043
0.085
0.125
0.161
0.161
0.161

0.999
0.996
0.985
0.966
0.940
0.940
0.940

-0.036
0.087
0.173
0.258
0.342
0.342
0.342

mp+SQRT(2mpaa+p^2+m^2)
ESS CONDN.

VALUE UNTIL BALANCE APPROACHE ZERO

ALUATION OF K'
12.623
11.045
11.834
12.465
11.991
11.045
12.623
12.623
12.623
12.623

-11.979
-9.601
-9.959
-10.244
-9.1997
-7.4359
-9.2587
-8.9169
-8.5945
-8.2887

UE UNTIL BALANCE APPROACHE ZERO

ALUATION OF K'
RHS BALANCE
0.0158 -0.0215
6.6268 1.49364
7.0213 2.78475
7.8891 2.23562

8.678
9.1513
9.7824
10.414
10.729
11.155

2.64788
3.35118
3.29417
3.02113
3.16983
-0.4823

UE UNTIL BALANCE APPROACH ZERO

ALUATION OF K'
RHS BALANCE
0.02
-0.0158
6.63
-6.621
7.02
-7.021
7.89
-7.885
8.68
-8.6592
9.15
-9.1172
9.78
-9.7232
10.41 -10.319
10.73 -10.618
1.89
-1.8439

ALUATION OF K'

* ADJUST VALUES OF Sc TO GET VALUES

a
0.773
0.792
0.808
0.821
0.833
0.844
0.853
0.861
0.868
0.875

K
0.156
0.152
0.148
0.144
0.141
0.138
0.135
0.132
0.130
0.127

Sc
2.45
2.40
2.30
2.30
2.20
2.20
2.10
2.10
2.05
2.00

LHS
133.64
137.56
137.88
143.65
142.69
147.77
145.73
150.25
150.94
151.30

RHS BALANCE
133.88 -0.24
137.16
0.41
139.93 -2.05
142.31
1.34
144.38 -1.68
146.18
1.59
147.77 -2.04
149.19
1.06
150.45
0.49
151.59 -0.29

H THE FACES

MAX.STEEL.
STRESS
N/SQ.MM

0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000

UES UNTIL e AND e(THETA) MATCH

DESIGN OF RCC FLARED CHIMNEY

DATA :
DESIGN CODE :

IS 4998 -(PART-1) :1992

IS 875 -(PART-3) :1987

LOCATION :

HYDERABAD

HEIGHT OF ABOVE GROUND=

HEIGHT BELOW GROUND =

46.000
4.000

M
M

HEIGHT OF FLAIR =
BASE DIAMETER OF FLAIR=Dbf=
TOP DIAMETER OF FLAIR =Dtf=
TOP THICKNESS OF FLAIR =
BOT. THICKNESS OF FLAIR=

26.000
4.200
3.000
0.300
0.500

M
M
M
M
M

BOTTOM DIA. OF STACK =Dbs=

TOP DIAMETER OF STACK =Dts=
TOP THICKNESS OF STACK=
BOT. THHICKNESS OF STACK=

3.000
2.000
0.200
0.300

M
M
M
M

THICKNESS OF LINING =
DENSITY OF LINING =
SPACING OF LINING SUPPORT BRACKETS =
SIZE OF LINING SUPPORT BRACKETS =

0.100
2.000
2.000
0.300

M
T/M^3
M
0.3

PERCENTAGE OF VERTICAL STEEL =

MXM

GRADE OF CONCRETE =Fck= 25

ALLOWABLE COMPRESSIVE STRESS IN CONCETE =
ALLOW. BENDING COMPRE. STRESS IN CONCRETE =
ALLOWABLE TENSILE STRESS IN CONCRETE =
MODULAR RATIO =m=
10.98039216
K=
0.289
J=
0.904

6
8.5
0.9

N/SQ.MM
N/SQ.MM
N/SQ.MM
Q=

1. DEAD LOAD & SECTIONAL PROPERTIES

Hx = HEIGHT FROM TOP = n x H
Dx = INNER DIAMETER AT HEIGHT Hx
Tx = THICKNESS AT Hx
Ax1 = CROSS SECTIONAL AREA OF CHIMNEY AT HEIGHT Hx
Ax2 = EQUVIVALENT CROSS SECTIONAL AREA OF STEEL AT HEIGHT Hx =(m-1)*Ax1*(n/100)
Wwx = WEIGHT OF WALL AT Hx
Wl = WEIGHT OF LINING AT Hx
I =MOMENT OF INERTIA
CALCULATION OF LOADS, SECTIONAL AREA , INERTIA AND STRESSES

Hx

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

Hx

Dx

Tx

Wwx

Wl

Wwx+Wl

MM

0.000
5.000
10.000
15.000
20.000
25.000
30.000
24.000
35.000
40.000
45.000
50.000

2.000
2.208
2.417
2.625
2.833
3.042
3.250
3.000
3.508
3.738
3.969
4.200

0.200
0.217
0.233
0.250
0.267
0.283
0.300
0.240
0.350
0.400
0.450
0.500

18.922
41.271
67.271
97.140
131.101
169.373
126.172
210.730
266.940
332.380
410.026

7.266
15.239
23.918
33.305
43.399
54.200
41.022
66.616
79.662
93.589
108.399

26.19
56.51
91.19
130.45
174.50
223.57
167.19
277.35
346.60
425.97
518.43

2. DEAD LOAD + WIND LOAD

STATIC (ALONG WIND LOAD) CONDITIOIN
K1,K2,K3 FROM IS:875 -PART -III -(1987)
Vb = DESIGN WIND SPEED , M/SEC
Pz=DESIGN WIND PRESSURE = 0.6 (K1*K2*K3*Vb)^2 N/SQ.M
Dxt = Dx + Tx
Vb x Dxt VALUES ARE COMPUTED AS PER TABLE-23 OF IS:875(PART-3)-1987
e = ECCENTRICITY OF LOAD
E-MAX = MAX. ALLOWABLE ECCENTRICITY FOR NO TENSION CONDITION
THETA=NEUTRAL AXIS ANGLE
e(THETA) = ECCENTRICITY DUE TO ANGLE THETA
HEIGHT / DIAMETER =
13.33333333
* REFER TABLE-23 IS:875(PART-3)-1987

* IS 4998 -(PART-1) :1992 CLAUSE

SHELL ALONE CASE WITHOUT LOADING IS CONSIDERED

CALCULATION OF WIND SHEAR , MOMENT AND STRESSES

Hx

Hx

K1

K2

K3

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

Vb

1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07

1.26
1.26
1.26
1.20
1.20
1.20
1.15
1.15
1.15
1.09
1.09
1.05

1.00
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

CALCULATION OF STRESS IN HOOP REINFORCEMENT

Pz
T/SQ.M

44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000

0.211
0.211
0.211
0.192
0.192
0.192
0.176
0.176
0.176
0.158
0.158
0.147

WIND SHEAR AT SECTION X = Hx

SPACING OF HOOP BARS =Sh
DIA . OF BAR = Db
AREA OF BAR = At
MEAN DIA. AT SECTION X = Dx-M
DISTANCE BETWEEN RFT. ON BOTH FACES =d= 0.8 * MEAN DIA. OF CHIMNEY
STRESS IN STEEL = Hsx. Sh / 1.6. At .d
CIRCUMFERENTIAL EFFECT DUE TO WIND
EXTERNAL AND INTERNAL RING MOMENTS=Me/Mi =0.33 . Pz. Rm^2
WIND PRESSURE AT HEIGHT X FROM TOP =Pzx
MEAN RADIUS OF SHEEL AT HEIGHT X FROM TOP = Rm
Hx

Hx

Hsx

SIZE OF

AREA OF

SPACING

(T)

BAR

BAR(At)

OF BARS

DIA.

(MM)

(MM)

(MM)

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

MEAN

0.00
5.00
1.863
8.0
50.272
200
2425.000
10.00
4.083
8.0
50.272
200
2650.000
15.00
6.350
8.0
50.272
200
2875.000
20.00
8.702
8.0
50.272
200
3100.000
25.00
11.688
8.0
50.272
200
3325.000
30.00
14.386
8.0
50.272
200
3550.000
24.00
11.678
8.0
50.272
200
3240.000
35.00
16.752
8.0
50.272
200
3857.692
40.00
19.496
8.0
50.272
200
4138.462
45.00
22.190
8.0
50.272
200
4419.231
50.00
25.121
8.0
50.272
200
4700.000
MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

3. DEAD LOAD +EARTH QUAKE LOAD

TOTAL WT. OF CHIMNEY =Wt=
518.43 T
HEIGHT ABOVE BASE =h'=
50 M
MODULUS OF ELASTICITYOF CONCRET=E=
1.91E+06 N/SQ.M
AREA OF C/S AT BASE=A =
8.121 SQ.M
RADIUS OF GYRATION AT BASE =Rg=
1.6702 M
HEIGHT / RADIUS OF GYRATION =K=
29.94 M

FOR K=
FOR K=
FOR K =

30
35
29.94

CT
56
65
55.89

CV
1.350
1.390
1.349

NATURAL PERIOD OF VIBRATION =

SOIL FOUNDATION SYSTEM =B=
IMPORTANCE FACTOR =
1.5
BASIC HORIZONTAL SEISMIC COEFF.=
HORIZONTAL SEISMIC COEFF=

2.08 SECS
1
0.02
0.03

CG OF TOWER FROM BASE =

28.070

SHELL ALONE CASE WITHOUT LOADING IS CONSIDERED

Hx

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

Hx

SHEAR

MOMENT

ECCTY.

ECCTY.

THETA

T-M

e(M)

E-MAX(M)

DEG

=M/W

NO TEN.

4.379
2.845
2.154
1.751
1.496
1.332
1.512
1.239
1.146
1.092
1.065

0.510
0.558
0.605
0.653
0.701
0.749
0.689
0.810
0.865
0.920
0.976

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

0.00
3.36
6.45
9.25
11.77
14.01
15.97
13.58
17.64
19.04
20.16
20.99

0.000
82.851
117.423
144.886
170.137
196.135
225.531
190.748
261.084
305.815
363.072
436.569

98.000
108.000
100.000
92.000
85.000
80.000
80.000
75.000
70.000
70.000
70.000

4. DEAD LOAD + TEMPERATURE LOADS

COEFFICIENT OF EXPANSION STEEL/CONCRETE =A=

1.10E-05 /DEGREE
CLEAR COVER TO REINFORCEMENT =
50 MM
COVER / DEPTH RATIO = a =
COVER / EFEECTIVE DEPTH AT THAT SECTION
ELASTIC MODULUS OF STEEL =Es=
2.10E+07 T/SQ.M
=
ELASTIC MODULUS OF CONCRETE=Ec=
1.91E+06 T/SQ.M
=
TEMPERATURE OF FLUME =
90
DEGREE
AMBIENT TEMPERATURE=
15
DEGREE
TEMP. GRADIENT= T=
75
DEGREE
K=NEUTARAL AXIS DEPTH CONSTANT AT TEMPERATURE STRESS CONDN.= -mp+SQRT(2mpaa+p^2+m^2)
K'=NEUTARAL AXIS DEPTH CONSTANT AT TEMPERATURE+(OTHER LOAD) STRESS CONDN.
Hx

Hx
M

STRESS

a=

S(Wwx+Wl)

COVER/EFF.DEPTH

MAX.CONC. MAX.STEEL.

K'

STRESS
N/SQ.MM

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

0.131
0.240
0.334
0.415
0.487
0.552
0.566
0.540
0.551
0.564
0.580

0.769
0.783
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

0.800
0.750
0.750
0.790
0.760
0.700
0.700
0.800
0.800
0.800
0.800

12.623
11.834
11.834
12.465
11.991
11.045
11.045
12.623
12.623
12.623
12.623

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

STRESS
N/SQ.MM

-5.544
5.476
8.121
3.790
10.157
19.404
14.042
9.240
11.880
13.860
15.400
11.305

5. DEAD LOAD + WIND LOAD +TEMPERATURE LOADS

5.A. COMPRESSION ZONE -LEEWARD SIDE
THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD
Hx

Hx
M

STRESS

a=

S(Wwx+Wl)

COVER/EFF.DEPTH

MAX.CONC. MAX.STEEL.

K'

+WINDLOAD

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

1.785
2.669
3.516
1.784
1.637
1.797
1.835
1.730
1.768
1.829
1.893

STRESS
N/SQ.MM

0.769
0.786
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

0.001
0.750
0.445
0.500
0.550
0.580
0.580
0.620
0.660
0.680
0.707

0.016
11.834
7.021
7.889
8.678
9.151
9.151
9.782
10.414
10.729
11.155

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

STRESS
N/SQ.MM

0.173
5.906
34.211
33.317
31.649
30.547
26.867
29.718
28.096
27.685
26.267
11.305

5.B. TENSION ZONE- WINDWARD SIDE

THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD
Hx

Hx
M

STRESS

a=

S(Wwx+Wl)

COVER/EFF.DEPTH

MAX.CONC. MAX.STEEL.

K'

+WINDLOAD

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

1.785
2.669
3.516
1.784
1.637
1.797
1.835
1.730
1.768
1.829
1.893

STRESS
N/SQ.MM

0.769
0.786
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

0.001
0.750
0.445
0.500
0.550
0.580
0.580
0.620
0.660
0.680
0.120

0.016
11.834
7.021
7.889
8.678
9.151
9.151
9.782
10.414
10.729
1.893

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

STRESS
N/SQ.MM

0.173
5.906
34.211
33.317
31.649
30.547
26.867
29.718
28.096
27.685
18.018
11.305

5.C. NEUTRAL AXIS

THE STRESSES CONSIDERED INCLUDE DEAD LOAD WITH LINING AND WIND LOAD

Hx

Hx
M

STRESS

a=

S(Wwx+Wl)

COVER/EFF.DEPTH

MAX.CONC. MAX.STEEL.

K'

+WINDLOAD

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

1.785
2.669
3.516
1.784
1.637
1.797
1.835
1.730
1.768
1.829
1.893

STRESS
N/SQ.MM

0.769
0.786
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

0.316
0.750
0.323
0.327
0.329
0.332
0.321
0.338
0.342
0.345
0.348

4.980
11.834
5.104
5.154
5.198
5.236
5.071
5.329
5.398
5.451
5.493

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

STRESS
N/SQ.MM

32.245
5.906
33.382
33.840
34.242
34.598
33.076
35.457
36.096
36.590
95.611
11.305

CALCULATION OF STRESS IN HOOP REINFORCEMENT

p=% HOOP REI9NFORCEMENT=At / SPACING x THICKNESS OF SHELL
K'=SQRT(2.m.p.a + p^2. M^2)-p.m
STRESS IN CONCRETE = Sc
STRESS IN STEEL =Sc = m . Sc. (a-K')/K'
Ss + m. Sc = Es. A. T .a
Sc(T) = TOTAL STRESS IN STEEL = STRESS DUE TO SHEAR + STRESS DUE TO TEMP
Hx

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.480
0.700
0.800
0.900
1.000

Hx

Hsx

SIZE OF

AREA OF

SPACING

(T)

BAR

BAR(At)

OF BARS

DIA.

(MM)

(SQ.MM)

(MM)

(MM)

10
10
10
10
10
10
10
10
10
10
10

78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55
78.55

200
200
200
200
200
200
200
200
200
200
200

2425.00
2650.00
2875.00
3100.00
3325.00
3550.00
3240.00
3857.69
4138.46
4419.23
4700.00

0.00
5.00
10.00
15.00
20.00
25.00
30.00
24.00
35.00
40.00
45.00
50.00

0.000
1.863
4.083
6.350
8.702
11.688
14.386
11.678
16.752
19.496
22.190
25.121

MAX. PERMISSIBLE COMPRESSIVE STRESS WITH WIND LOAD=

DESIGN OF FOUNDATION
ADOPT CIRCULAR RAFT FOR FOUNDATION
DENSITY OF SOIL =
DEPTH OF FOUNDATION =
SBC OF SOIL =

1.8
20

T/Cu.M
4
T/SQ.M

MEAN

230

THICKNESS OF RAFT=

1000

MM

LOADS & MOMENTS

PROJECTION OF RAFT BEYOND WALL =
DIAMETER OF RAFT =
9.70
AREA OF RAFT =
73.91
SECTION MODULUS =
89.61
SELF WEIGHT OF CHIMNEY =
WEIGHT OF LININING =
WEIGHT OF FOUNDATION =
WEIGHT OF EARTH =
TOTAL LOAD =

2.75

M
SQ.M
Cu.M
410.026
108.399
77.764
432.371
1028.560

T
T
T
T
T

* 15 % OF TOTAL WEIGHT

A. SELF WEIGHT OF CHIMNEY + WIND LOAD

CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED
TOTAL LOAD =
MOMENT DUE TO WIND =
MAX. SOIL PRES. =
MIN. SOIL PRES. =

920.161

19.46
5.44

DIA .OF SHAFT=2b=

DIA.OF RAFT SLAB=2a=

T
628.04

T-M

T/SQ.M
T/SQ.M
5.2 M
9.70 M

* P/A +M/Z
*P/A-M/Z
b=
a=

2.6
4.85

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =

46.85815 T-M
10.36444 T-M

B. SELF WEIGHT OF CHIMNEY + LINING WIGHT + EARTHQUAKE LOAD

TOTAL LOAD =
MOMENT DUE TO EARTH QUA. =
MAX. SOIL PRES. =
MIN. SOIL PRES. =

1028.560

18.79
9.05

DIA .OF SHAFT=2b=

DIA.OF RAFT SLAB=2a=

T
436.57

T-M

T/SQ.M
T/SQ.M
5.2 M
9.70 M

* P/A +M/Z
*P/A-M/Z
b=
a=

2.6
4.85

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =
DESIGN RADIAL BM AT CENTRE OF RAFT =
DESIGN RADIAL BM AT FACE OF SHAFT =

56.13286 T-M
20.89557 T-M
56.13286
20.895566

DEPTH OF FOUNDATION REQUIRED =

DEPTH OF FOUNDATION ADOPTED =
CLEAR COVER =
SIZE OF BAR =
EFFECTIVE DEPTH =

711.64 MM
1000 MM
50 MM
25 MM
937.5 MM

MIN. AREA OF STEEL REQUIRED/FACE =

600 SQ.MM

AREA OF STEEL FOR RADIAL BM AT CENTRE OF RAFT =

SIZE OF BAR =
25 MM
AREA OF BAR =
490.9375 SQ.MM
NO. OF BARS =
5.865748
SPACING OF BARS =
170.4812334 MM
AREA OF STEEL FOR RADIAL BM AT FACE OF SHAFT =
SIZE OF BAR =
12 MM
AREA OF BAR =
113.112 SQ.MM
NO. OF BARS =
9.477154
SPACING OF BARS =
105.5169132 MM
PROVIDE 20 MM BARS AT 100 MM C/C IN RADIAL DIRECTION ON BOTH THE FACES

MIN. AREA OF STEEL IN RAFT /FACE =

600 SQ.MM

SIZE OF BAR =
12 MM
AREA OF BAR =
113.112 SQ.MM
NO. OF BARS =
5.304477
SPACING OF BARS =
188.52 MM
PROVIDE 12 MM BARS AT 175 MM C/C IN CICUMFERENTIAL DIRECTION ON BOTH THE FACES

CHECK FOR STABILITY

A. SELF WEIGHT OF CHIMNEY + WIND LOAD
CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED
TOTAL VERTICAL LOAD =
TOTAL HORIZONTAL LOAD =
MOMENT DUE TO WIND =
RESISTING MOMENT =

920.16
25.121
628.04
4462.78 T-M

T
T
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

FACTOR OF SAFETY AGAINST SLIDING =

7.11
21.98 >1.5

B. SELF WEIGHT OF CHIMNEY + WEIGHT OF LINING + EARTH QUAKE LOAD

TOTAL VERTICAL LOAD =
TOTAL HORIZONTAL LOAD =
MOMENT DUE TO EARTH QUA. =
RESISTING MOMENT =

1028.56
20.988
436.57
4988.52 T-M

T
T
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

FACTOR OF SAFETY AGAINST SLIDING =

11.43
29.40 >1.5

*BxD

1.1084

Sst =

230 N/SQ.MM

=(m-1)*Ax1*(n/100)

S(Wwx)

S(Wwx+Wl)

Ax1

Ax2

Ax1+Ax2

Ts

Ie

SQ.M

SQ.M

SQ.M

M^4

MAX.CONC. MAX.CONC.
STRESS

STRESS

1.816
2.137
2.484
2.857
3.255
3.680
2.687
4.666
5.720
6.872
8.121

0.181
0.213
0.248
0.285
0.325
0.367
0.268
0.466
0.571
0.686
0.810

1.997
2.350
2.732
3.142
3.580
4.047
2.955
5.131
6.291
7.558
8.931

0.002
0.002
0.002
0.003
0.003
0.003
0.002
0.003
0.004
0.004
0.005

1.344
1.889
2.584
3.454
4.528
5.835
3.543
8.744
12.350
16.933
22.653

0.095
0.176
0.246
0.309
0.366
0.418
0.427
0.411
0.424
0.440
0.459

0.131
0.240
0.334
0.415
0.487
0.552
0.566
0.540
0.551
0.564
0.580

* FLAIR HEIGHT =TOP OF FLAIR

* FLAIR PORTION

ABLE-23 IS:875(PART-3)-1987

* IS 4998 -(PART-1) :1992 CLAUSE:5.3

SHAPE

WIND

TOTAL

WIND

ECCTY.

ECCTY.

THETA

ECCTY.

FACTOR

PRES.

LOAD(T)

MOMENT

e(M)

E-MAX(M)

DEG

e(THETA)

Hsx

(T-M)

1.863
4.083
6.350
8.702
11.688
14.386
11.678
16.752
19.496
22.190
25.121

4.657
20.414
47.63
87.02
146.10
215.78
140.14
293.16
389.92
499.27
628.04

0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700

0.148
0.148
0.148
0.134
0.134
0.134
0.123
0.123
0.123
0.111
0.111
0.103

=M/W

0.246
0.495
0.708
0.896
1.114
1.274
1.111
1.391
1.461
1.502
1.532

NO.TENSION (T)

0.561
0.609
0.656
0.704
0.751
0.799
0.623
0.885
0.933
0.987
1.042

MAX.CONC.
STRESS
N/SQ.MM

12.00
15.00
16.00
45.00
68.00
75.00
75.00
80.00
83.00
82.00
84.00

9.711
8.421
8.542
3.100
2.142
2.061
1.881
2.092
2.159
2.335
2.421

1.749
2.604
3.428
1.678
1.516
1.663
1.697
1.601
1.641
1.705
1.772

STRESS
IN STEEL

RING
MOM.
T-M

19.10
0.102
38.31
0.122
54.92
0.131
69.80
0.152
87.40
0.175
100.76
0.183
89.62
0.152
107.97
0.216
117.14
0.223
124.85
0.255
132.90
0.267
230 N/SQ.MM

1.9E+06 T/SQ.M

* IS 4998 -(PART-1) :1992 CLAUSE:5.3

ECCTY.
e(THETA)

1.427
2.235
1.797
1.559
1.441
1.407
1.284
1.415
1.417
1.513
1.609

MAX.CONC. MAX.STEEL.
STRESS

STRESS

N/SQ.MM

N/SQ.MM

0.406
0.893
1.084
1.217
1.329
1.445
1.473
1.356
1.345
1.396
1.459

5.913
18.611
16.927
14.346
12.272
11.186
11.398
8.777
7.250
7.523
7.861

* ADJUST THETA VALUES UNTIL e AND e(THETA) MATCH

THETA

1.711
1.886
1.746
1.606
1.484
1.397
1.397
1.310
1.222
1.222
1.222

SIN(2xT)

-0.069
-0.147
-0.086
-0.018
0.043
0.085
0.085
0.125
0.161
0.161
0.161

2.10E+05 N/SQ.MM
1.91E+04 N/SQ.MM

DN.= -mp+SQRT(2mpaa+p^2+m^2)
D) STRESS CONDN.

* ADJUST K' VALUE UNTIL BALANCE APPROACHE ZERO

EVALUATION OF K'
0.769
0.783
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900
N/SQ.MM

0.8
0.7
0.75
0.79
0.76
0.7
0.7
0.8
0.8
0.8
0.8

0.356818
0.784834
0.99856
1.165284
1.445503
1.846036
1.853929
1.515813
1.554797
1.598417
1.652726

12.6225
11.04469
11.83359
12.46472
11.99138
11.04469
11.04469
12.6225
12.6225
12.6225
12.6225

-12.26568
-10.25985
-10.83503
-11.29943
-10.54587
-9.198652
-9.190758
-11.10669
-11.0677
-11.02408
-10.96977

SIN(T)

0.990
0.951
0.985
0.999
0.996
0.985
0.985
0.966
0.940
0.940
0.940

COS(T)

-0.140
-0.310
-0.174
-0.036
0.087
0.173
0.173
0.258
0.342
0.342
0.342

* ADJUST K' VALUE UNTIL BALANCE APPROACHE ZERO

EVALUATION OF K'
LHS
RHS
BALANCE
0.769
0.001
-0.023276 0.015778 -0.039055
0.786
0.420
25.65901 6.626813 19.0322
0.800
0.445
28.66469 7.021266 21.64343
0.813
0.500
10.81826 7.889063 2.929194
0.824
0.550
8.168853 8.677969 -0.509116
0.833
0.580
8.164306 9.151313 -0.987007
0.792
0.580
8.076432 9.151313 -1.07488
0.857
0.620
7.101433 9.782438 -2.681004
0.875
0.660
6.607025 10.41356 -3.806537
0.889
0.680
6.566239 10.72913 -4.162886
0.900
0.707
6.436435 11.15513 -4.718699
N/SQ.MM

* ADJUST K' VALUE UNTIL BALANCE APPROACH ZERO

EVALUATION OF K'
LHS
RHS
BALANCE
0.769
0.001
0.00
0.02
-0.015755
0.786
0.420
1.93
6.63
-4.693312
0.800
0.445
0.04
7.02
-6.977169
0.813
0.500
0.03
7.89
-7.861198
0.824
0.550
0.03
8.68
-8.645874
0.833
0.580
0.04
9.15
-9.110792
0.792
0.580
0.05
9.15
-9.101198
0.857
0.620
0.05
9.78
-9.737254
0.875
0.660
0.06
10.41
-10.35807
0.889
0.680
0.06
10.73
-10.66741
0.900
0.120
0.07
1.89
-1.819784
N/SQ.MM

EVALUATION OF K'
0.769
0.786
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

0.316
0.320
0.323
0.327
0.329
0.332
0.321
0.338
0.342
0.345
0.348

N/SQ.MM

UE TO TEMP
% STEEL

STRESS IN

(p)

CONCERET
(N/SQ.MM)

0.00181
0.00168
0.00157
0.00147
0.00139
0.00131
0.00164
0.00112
0.00098
0.00087
0.00079
N/SQ.MM

2.450
2.400
2.300
2.300
2.200
2.200
2.200
2.100
2.100
2.050
2.000

STRESS IN
STEEL

* ADJUST VALUES OF Sc TO GET VALUES

(N/SQ.MM)

124.669
147.343
164.562
184.381
201.550
219.295
191.565
232.925
252.947
267.299
280.926

a
0.769
0.786
0.800
0.813
0.824
0.833
0.792
0.857
0.875
0.889
0.900

K
0.156
0.153
0.150
0.147
0.144
0.141
0.152
0.134
0.127
0.121
0.116

Sc
2.45
2.40
2.30
2.30
2.20
2.20
2.20
2.10
2.10
2.05
2.00

LHS
132.47
135.39
134.89
139.83
138.30
142.69
126.10
148.01
158.87
164.96
169.99

RHS
133.27
136.13
138.60
140.77
142.68
144.38
137.16
148.50
151.59
154.00
155.93

BALANCE
-0.80
-0.74
-3.71
-0.93
-4.37
-1.68
-11.06
-0.49
7.28
10.96
14.06

* 15 % OF TOTAL WEIGHT

M
M

M
M

T-M
T-M

2879.716 SQ.MM

1071.98 SQ.MM

ON BOTH THE FACES

>1.5
SAFE

SAFE

>1.5
SAFE

SAFE

HEIGHT =TOP OF FLAIR

MAX.STEEL.

* ADJUST THETA VALUES UNTIL e AND e(THETA) MATCH

STRESS
N/SQ.MM

THETA

SIN(2xT)

SIN(T)

0.102
0.125
0.133
0.250
0.173
0.125
0.125
0.085
0.060
0.069
0.052

0.208
0.259
0.276
0.707
0.927
0.966
0.966
0.985
0.993
0.990
0.995

RAD.

19.204
28.592
37.646
18.426
16.644
18.259
18.629
17.576
18.018
18.718
19.457

0.210
0.262
0.279
0.786
1.187
1.310
1.310
1.397
1.449
1.432
1.467

DESIGN OF STEEL FLARED CHIMNEY

DATA :
DESIGN CODE :

IS 6533 -(PART-2) :1989

IS 875 -(PART-3) :1987

LOCATION :

HYDERABAD

HEIGHT OF ABOVE GROUND=

80.000

HEIGHT OF FLAIR =
BASE DIAMETER OF FLAIR=Dbf=
TOP DIAMETER OF FLAIR =Dtf=
TOP THICKNESS OF FLAIR =
BOT. THICKNESS OF FLAIR=

25.000
4.500
3.000
16.000
16.000

M
M
M
MM
MM

BOTTOM DIA. OF STACK =Dbs=

TOP DIAMETER OF STACK =Dts=
TOP THICKNESS OF STACK=
BOT. THICKNESS OF STACK=

3.000
3.000
8.000
8.000

M
M
MM
MM

CORROSION ALLOWANCE FOR PLATES =

0.000

MM

THICKNESS OF LINING =
DENSITY OF LINING =
SPACING OF LINING SUPPORT BRACKETS =
SIZE OF LINING SUPPORT BRACKETS =

0.100
2.000
2.000
0.300

M
T/M^3
M
0.3

YIELD STRENGTH OF STEEL = Fy =

250.000

GRADE OF CONCRETE =Fck=

25
ALLOWABLE COMPRESSIVE STRESS IN CONCETE =
ALLOW. BENDING COMPRE. STRESS IN CONCRETE =
ALLOWABLE TENSILE STRESS IN CONCRETE =
ALLOWABLE BEARING STRESS =
K=
0.289
J=

N/SQ.MM

6
8.5
0.9
6.25
0.904

MXM

N/SQ.MM
N/SQ.MM
N/SQ.MM
N/SQ.MM
Q=

1. DEAD LOAD & SECTIONAL PROPERTIES

Hx = HEIGHT FROM TOP = n x H
Dx = INNER DIAMETER AT HEIGHT Hx
Tx = THICKNESS AT Hx
Tx-FIANL=THICKNESS OF SHELL AFTER CORROSION
Ax = CROSS SECTIONAL AREA OF CHIMNEY AT HEIGHT Hx ( WITH CORROSION ALLOWANCE)
Wwx = WEIGHT OF WALL AT Hx
Wl = WEIGHT OF LINING AT Hx
I =MOMENT OF INERTIA & Z = SECTION MODULUS
Rg = RADIUS OF GYRATION = 0.707*Dx/Tx-FINAL
He = EFFECTIVE HEIGHT = 2*Hx

* INDUCED STRESSES
* ALLOWABLE STRESSES
CALCULATION OF LOADS, SECTIONAL AREA , INERTIA AND STRESSES
Hx

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.688
0.700
0.800
0.900
1.000

Hx

Dx

Tx

Wwx

Wl

Wwx+Wl

MM

0.000
8.000
16.000
24.000
32.000
40.000
48.000
55.000
56.000
64.000
72.000
80.000

3.000
3.000
3.000
3.000
3.000
3.000
3.000
3.000
3.060
3.540
4.020
4.500

8.000
8.000
8.000
8.000
8.000
8.000
8.000
16.000
16.000
16.000
16.000
16.000

4.751
9.501
14.252
19.003
23.753
28.504
49.056
50.446
62.201
75.093
89.122

15.082
30.163
45.245
60.326
75.408
90.490
103.686
106.627
131.512
158.809
188.520

19.83
39.66
59.50
79.33
99.16
118.99
152.74
157.07
193.71
233.90
277.64

2. DEAD LOAD + WIND LOAD + TEMPERATURE LOAD

STATIC (ALONG WIND LOAD) CONDITIOIN
K1,K2,K3 FROM IS:875 -PART -III -(1987)
Vb = DESIGN WIND SPEED , M/SEC
Pz=DESIGN WIND PRESSURE = 0.6 (K1*K2*K3*Vb)^2 N/SQ.M
Dxt = Dx + Tx
Vb x Dxt VALUES ARE COMPUTED AS PER TABLE-23 OF IS:875(PART-3)-1987
e = ECCENTRICITY OF LOAD
E-MAX = MAX. ALLOWABLE ECCENTRICITY FOR NO TENSION CONDITION
THETA=NEUTRAL AXIS ANGLE
e(THETA) = ECCENTRICITY DUE TO ANGLE THETA
HEIGHT / DIAMETER =
5.079365079
* REFER TABLE-23 IS:875(PART-3)-1987

FOR WINDWARD SIDE THE MAX. TESILE STRESSES OCCUR DURING NO LINING CONDITION
FOR LEEWARD SIDE THE MAX. COMPRESSIVE STRESSES OCCUR WITH LINING CONDITION
THE MAX. ALLOWABLE STRESS VALUES ARE INCREASED BY 1.33 TO ACCOUNT FOR WIND LOAD CONDIT
MAX. EXHAUST GAS TEMPERATURE=
200
DEGREES
TEMP. CORRECTION CO-EFF. FOR MAX. ALLOWABLE STRESS =

0.75

THE ALLOWABLE MAX. STRESSES ARE MODIFIED TO ACCOMMODATE FOR TEMPERATURE EFFECTS.
CALCULATION OF SHEAR , MOMENT AND STRESSES
Hx

Hx

K1

K2

0.000

0.00

K3

Vb

1.07

1.26

0.90

Pz
T/SQ.M

44.000

0.171

0.100
0.200
0.300
0.400
0.500
0.600
0.688
0.700
0.800
0.900
1.000

8.00
16.00
24.00
32.00
40.00
48.00
55.00
56.00
64.00
72.00
80.00

1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07
1.07

1.26
1.26
1.20
1.20
1.20
1.15
1.15
1.15
1.09
1.09
1.05

0.900
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000
44.000

0.171
0.211
0.192
0.192
0.192
0.176
0.176
0.176
0.158
0.158
0.147

3. DEAD LOAD +EARTH QUAKE LOAD + TEMPERATURE LOAD

TOTAL WT. OF CHIMNEY =Wt=
HEIGHT ABOVE BASE =h'=
MODULUS OF ELASTICITYOF STEEL=E=
AREA OF C/S AT BASE=A =
RADIUS OF GYRATION AT BASE =Rg=
HEIGHT / RADIUS OF GYRATION =K=

FOR K=
FOR K=
FOR K =

30
35
50.29

CT
56
65
92.52

277.64 T
80.000 M
2.10E+05 N/SQ.MM =
0.226 SQ.M
1.5908 M
50.29 M

CV
1.350
1.390
1.512

NATURAL PERIOD OF VIBRATION =

SOIL FOUNDATION SYSTEM =B=
IMPORTANCE FACTOR =
1.5
BASIC HORIZONTAL SEISMIC COEFF.=
HORIZONTAL SEISMIC COEFF=
CG OF TOWER FROM BASE =
Hx

0.96 SECS
1
0.02
0.03

40.000

Hx

SHEAR

MOMENT

TENSLIE

COMPVE.

ALLOW.

T-M

STRESS

STRESS

STRESS.

0.00
8.00
16.00
24.00
32.00
40.00
48.00
55.00
56.00
64.00
72.00
80.00

0.000
2.019
3.870
5.551
7.064
8.408
9.583
10.473
10.590
11.428
12.096
12.597

0.000
63.228
89.612
110.571
129.841
149.682
172.115
195.523
199.248
233.385
277.082
333.171

COMPVE.

0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.688
0.700
0.800
0.900
1.000

-10.461
-14.459
-17.505
-20.255
-23.105
-26.410
-13.759
-13.389
-11.124
-9.765
-9.013

13.721
20.979
27.285
33.295
39.405
45.970
27.139
26.878
25.504
25.055
25.225

86.72
83.69
79.08
73.42
67.23
60.96
87.06
86.40
80.86
75.40
70.34

DESIGN OF BASE PLATE

GRADE OF CONCRETE =Fck=
25
ALLOWABLE COMPRESSIVE STRESS IN CONCETE =
ALLOW. BENDING COMPRE. STRESS IN CONCRETE =
ALLOWABLE TENSILE STRESS IN CONCRETE =
ALLOWABLE BEARING STRESS =
K=
0.289
J=

6
8.5
0.9
6.25
0.904

N/SQ.MM
N/SQ.MM
N/SQ.MM
N/SQ.MM
Q=

GRADE OF BASE PLATE =

FE-410-WA
ALLOWABLE YIELD STRESS=
250 N/SQ.MM
ALLOWBLE TENSILE STRESS=
150 N/SQ.MM
ALLOWBLE COMPR. STRESS=
150 N/SQ.MM
ALLOWABLE SHEAR STRESS=
112.5 N/SQ.MM
ALLOW.BEARING STRESS=
187.5 N/SQ.MM
ALLOWBLE BENDING TENSILE STRESS=
165 N/SQ.MM
ALLOWBLE BENDING COMPR. STRESS=
165 N/SQ.MM
A.SELF WEIGHT OF CHIMNEY + WIND LOAD
TOTAL WT. OF CHIMNEY =Wt=
WIND MOMENT AT BASE=

89.12
1453.45

T
T-M

WIDTH OF SUPPORTING BASE PLATE =

THCIKNESS OF BASE PLATE =
SIZE OF STIFFENING ANGLE=
BASE DIAMETER OF FLAIR=Dbf=

0.45 M
36 MM
150
4.500 M

AREA OF BASE PLATE =

MOMENT OF INERTIA =
SECTION MODULUS =

6.363 SQ.M
9.343 M^4
3.775 M^3

MAX. COMPVE. STRESS =

MIN. STRESS=

5.68 N/SQ.MM
-3.71 N/SQ.MM

150

<

18

6.25

THE ANCHOR BOLTS ARE PROVIDED ON INSIDE AND OUTSIDE OF CHIMNEY SHELL
SIZE OF ANCHOR BOLT =
EDGE DISTANCE =
SPACING BETWEEN ROWS OF BOLTS=
MAX. PROJECTION OF BASE PLATE=
MAX. BM IN BASE PLATE =
MAX. STRESS IN PLATE =

40 MM
100 MM
0.25 M
0.191 M
10.353 T-M
213.02 N/SQ.MM

<

* FOR METER LENGTH ALONG C

219.45

DESIGN OF ANCHOR BOLTS

TOT.TENSILE LOAD IN BOLTS =
-1180.308 T
AREA OF ANCHOR BOLT =
1256.800 SQ./MM
CAPACITY OF ANCHOR BOLT IN TENSION=
18.85 T
CAPACITY OF ANCHOR BOLT IN SHEAR=
28.28 T
CAPACITY OF ANCHOR BOLT IN BEARING=
40.50 T

*DOUBLE SHEAR

NO. OF ROWS OF ANCHOR BOLTS =

NO. OF ANCHOR BOLTS REQUIRED =
SPACING OF ANCHOR BOLTS =

2
31
226 MM

* ALONG PERIPHERY

B. SELF WEIGHT OF CHIMNEY + LINING WIGHT + EARTHQUAKE LOAD

TOTAL WT. OF CHIMNEY =Wt=
WIND MOMENT AT BASE=

277.64 T
333.17 T-M

WIDTH OF SUPPORTING BASE PLATE =

THCIKNESS OF BASE PLATE =
SIZE OF STIFFENING ANGLE=
BASE DIAMETER OF FLAIR=Dbf=

0.45 M
36 MM
150
4.500 M

AREA OF BASE PLATE =

MOMENT OF INERTIA =
SECTION MODULUS =

150

18

6.363 SQ.M
9.343 M^4
3.775 M^3

MAX. COMPVE. STRESS =

MIN. STRESS=

6.569 N/SQ.MM
-0.4462 N/SQ.MM

<

6.25

THE ANCHOR BOLTS ARE PROVIDED ON INSIDE AND OUTSIDE OF CHIMNEY SHELL
SIZE OF ANCHOR BOLT =
EDGE DISTANCE =
SPACING BETWEEN ROWS OF BOLTS=
MAX. PROJECTION OF BASE PLATE=
MAX. BM IN BASE PLATE =
MAX. STRESS IN PLATE =

40 MM
100 MM
0.25 M
0.207 M
28.149 T-M
579.20 N/SQ.MM

<

* FOR METER LENGTH ALONG C

219.45

DESIGN OF ANCHOR BOLTS

TOT.TENSILE LOAD IN BOLTS =
-141.952 T
AREA OF ANCHOR BOLT =
1256.800 SQ./MM
CAPACITY OF ANCHOR BOLT IN TENSION=
18.85
CAPACITY OF ANCHOR BOLT IN SHEAR=
14.14
CAPACITY OF ANCHOR BOLT IN BEARING=
40.50
NO. OF ROWS OF ANCHOR BOLTS =
2
NO. OF ANCHOR BOLTS REQUIRED =
4
SPACING OF ANCHOR BOLTS =
1878

T
T
T

*DOUBLE SHEAR

MM

* ALONG PERIPHERY

PROVIDE ISA-150x150x18 MM STIFFENER ANGLE WITH 40 MM BASE PLATE AND

40 MM DIA. ANCHOR BOLTS 1000 MM LONG
DESIGN OF FOUNDATION
ADOPT CIRCULAR RAFT FOR FOUNDATION
DENSITY OF SOIL =
DEPTH OF FOUNDATION =
SBC OF SOIL =

1.80
4.00
20.00

T/Cu.M
M
T/SQ.M

THICKNESS OF RAFT=
DIA. OF CICULAR PEDESTAL=
HEIGHT OF PEDESTAL =

1100.00
5.50
2.90

MM

LOADS & MOMENTS

PROJECTION OF RAFT SHELL WALL =
DIAMETER OF RAFT =
12.50
AREA OF RAFT =
122.73
SECTION MODULUS =
191.77

4.00
M
SQ.M
Cu.M

SELF WEIGHT OF CHIMNEY =

WEIGHT OF LININING =
WEIGHT OF FOUNDATION =
WEIGHT OF EARTH =
WT.OFCIRCULAR PEDESTAL=
TOTAL LOAD =

T
T
T
T
T
T

89.122
188.520
41.646
820.062
172.270
1311.621

* 15 % OF TOTAL WEIGHT

A. SELF WEIGHT OF CHIMNEY + WIND LOAD

CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED
TOTAL LOAD =
MOMENT DUE TO WIND =
MAX. SOIL PRES. =
MIN. SOIL PRES. =

1224.831
1453.45

T
T-M

17.56
0.17

T/SQ.M
T/SQ.M

DIA .OF SHAFT/PEDESTAL=2b=

DIA.OF RAFT SLAB=2a=

5.50 M
12.50 M

* P/A +M/Z
*P/A-M/Z
b=
a=

2.75
6.25

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =

94.034861 T-M
15.227035 T-M

B. SELF WEIGHT OF CHIMNEY + LINING WIGHT + EARTHQUAKE LOAD

TOTAL LOAD =
1311.621
MOMENT DUE TO EARTH QUA. =
MAX. SOIL PRES. =
MIN. SOIL PRES. =

12.42
8.95

DIA .OF SHAFT/PEDESTAL=2b=

DIA.OF RAFT SLAB=2a=

T
333.17
T/SQ.M
T/SQ.M

T-M
* P/A +M/Z
*P/A-M/Z

5.50 M
12.50 M

b=
a=

THE RADIAL MOMENT IN THE SLAB GOVERNS THE DESIGN

RADIAL BM AT CENTRE OF RAFT =
RADIAL BM AT FACE OF SHAFT =

109.74295 T-M
53.980603 T-M

2.75
6.25

DESIGN RADIAL BM AT CENTRE OF RAFT =

DESIGN RADIAL BM AT FACE OF SHAFT =
DEPTH OF FOUNDATION REQUIRED =
DEPTH OF FOUNDATION ADOPTED =
CLEAR COVER =
SIZE OF BAR =
EFFECTIVE DEPTH =

109.74295 T-M
53.980603 T-M
995.03888 MM
1100 MM
50 MM
25 MM
1037.5 MM

MIN. AREA OF STEEL REQUIRED/FACE =

660 SQ.MM

AREA OF STEEL FOR RADIAL BM AT CENTRE OF RAFT =

SIZE OF BAR =
25 MM
AREA OF BAR =
490.9375 SQ.MM
NO. OF BARS =
10.36254
SPACING OF BARS =
96.50147697 MM

5087.357 SQ.MM

AREA OF STEEL FOR RADIAL BM AT FACE OF SHAFT =

2502.381 SQ.MM
SIZE OF BAR =
12 MM
AREA OF BAR =
113.112 SQ.MM
NO. OF BARS =
22.12303
SPACING OF BARS =
45.20175789 MM
PROVIDE 20 MM BARS AT 100 MM C/C IN RADIAL DIRECTION ON BOTH THE FACES

MIN. AREA OF STEEL IN RAFT /FACE =

660 SQ.MM

SIZE OF BAR =
12 MM
AREA OF BAR =
113.112 SQ.MM
NO. OF BARS =
5.834925
SPACING OF BARS =
171.3818182 MM
PROVIDE 12 MM BARS AT 175 MM C/C IN CICUMFERENTIAL DIRECTION ON BOTH THE FACES

CHECK FOR STABILITY

A. SELF WEIGHT OF CHIMNEY + WIND LOAD
CHIMNEY WITHOUT LINING WITH WIND LOAD IS CONSIDERED
TOTAL VERTICAL LOAD =
TOTAL HORIZONTAL LOAD =
MOMENT DUE TO WIND =
RESISTING MOMENT =

1224.83
36.336
1453.45
7655.19

T
T
T-M
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

FACTOR OF SAFETY AGAINST SLIDING =

5.27 >1.5

SAFE

20.22 >1.5

SAFE

B. SELF WEIGHT OF CHIMNEY + WEIGHT OF LINING + EARTH QUAKE LOAD

TOTAL VERTICAL LOAD =

1311.62

TOTAL HORIZONTAL LOAD =

MOMENT DUE TO EARTH QUA. =
RESISTING MOMENT =

12.597
333.17
8197.63

T
T-M
T-M

FACTOR OF SAFETY AGAINST OVERTURNING =

24.60 >1.5

SAFE

FACTOR OF SAFETY AGAINST SLIDING =

62.48 >1.5

SAFE

*BxD

1.1084

ROSION ALLOWANCE)

Sst =

230 N/SQ.MM
A

1.176
1.135
1.072
0.996
0.912
0.827
0.755
0.756
0.762
0.767
0.771

0.591
0.591
0.591
0.591
0.591
0.591
0.925
0.917
0.851
0.788
0.731

VALUES OF A AND B ARE FROM ANNEX-C IS:6533(PART-2)-1989

S(Wwx)

S(Wwx+Wl)

Tx-FIANL

Ax

MAX.STRESSMAX.STRESS Dx/Tx-FINAL

MM

SQ.M

M^4

M^3

N/SQ.MM

N/SQ.MM

8.000
8.000
8.000
8.000
8.000
8.000
16.000
16.000
16.000
16.000
16.000

0.075
0.075
0.075
0.075
0.075
0.075
0.151
0.154
0.178
0.202
0.226

0.086
0.086
0.086
0.086
0.086
0.086
0.172
0.183
0.283
0.413
0.579

0.0570
0.0570
0.0570
0.0570
0.0570
0.0570
0.1149
0.1195
0.1596
0.2055
0.2572

0.630
1.260
1.890
2.520
3.150
3.780
3.253
3.279
3.495
3.716
3.940

2.630
5.260
7.890
10.520
13.150
15.780
10.128
10.211
10.885
11.574
12.273

375.000
375.000
375.000
375.000
375.000
375.000
187.500
191.250
221.250
251.250
281.250

TABLE-23 IS:875(PART-3)-1987

O LINING CONDITION
H LINING CONDITION
CCOUNT FOR WIND LOAD CONDITION

FOR TEMPERATURE EFFECTS.

SHAPE

WIND

TOTAL

WIND

WINDWARD

LEEWARD

ALLOW.

FACTOR

PRES.

LOAD(T)

MOMENT

TENSILE

COMPVE.

STRESS.

Hsx

(T-M)

0.700

0.120

RAD. OF

He / Rg

GYR. (Rg)

COMPVE.

1.061
1.061
1.061
1.061
1.061
1.061
1.061
1.082
1.251
1.421
1.591

15.087
30.174
45.262
60.349
75.436
90.523
103.725
103.540
102.286
101.332
100.581

0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700

0.120
0.148
0.134
0.134
0.134
0.123
0.123
0.123
0.111
0.111
0.103

2.1E+07 T/SQ.M

2.873
6.420
10.147
12.869
16.087
18.516
20.314
20.890
24.681
30.102
36.336

11.493
51.362
121.76
205.91
321.73
444.39
558.64
584.93
789.79
1083.68
1453.45

-1.386
-7.749
-19.468
-33.598
-53.284
-74.170
-45.353
-45.653
-45.977
-49.007
-52.565

4.646
14.269
29.248
46.638
69.584
93.730
58.733
59.142
60.357
64.297
68.777

86.72
83.69
79.08
73.42
67.23
60.96
87.06
86.40
80.86
75.40
70.34

1.1084

Sst =

230 N/SQ.MM

* ROLLED ANGLE

N/SQ.MM ALLOWABLE BEARING STRESS

MNEY SHELL

* FOR METER LENGTH ALONG CICURCUMFERENCE

N/SQ.MM * 1.33 x ALLOWABLE BENDING STRESS WITH WIND LOAD

*DOUBLE SHEAR

* ALONG PERIPHERY

* ROLLED ANGLE

N/SQ.MM ALLOWABLE BEARING STRESS

MNEY SHELL

* FOR METER LENGTH ALONG CICURCUMFERENCE

N/SQ.MM * 1.33 x ALLOWABLE BENDING STRESS WITH WIND LOAD

*DOUBLE SHEAR

* ALONG PERIPHERY

TOTAL WEIGHT

M
M

M
M

ON BOTH THE FACES

ALLOW.
STRESS.

86.937
83.898
79.278
73.604
67.402
61.108
87.283
86.617
81.060
75.588
70.515

* FLAIR HEIGHT =TOP OF FLAIR

* FLAIR PORTION