15 Design of RCC Dome 23052014

Design of Concrete Domes as per IS 456Design of Concrete Domes as per IS 456Design of Concrete Domes as per IS 456Design of Concrete Domes as per IS 456

1)1)1)1)

radius of dome

2)2)2)2) Loading :Loading :Loading :Loading :

3)3)3)3) Calculation of Stresses due to Combined Loading :Calculation of Stresses due to Combined Loading :Calculation of Stresses due to Combined Loading :Calculation of Stresses due to Combined Loading :

Table 2

Prep By : A B Quadri- Abq Consultants - 9959010210 - [email protected]/2 Royal Residency, Besides Amba talkies, Mehdipatnam , Hyderabad-India. 500028-w.abqconsultants.com

-0.2211

90.0000 0.3000 0.0030 0.3030 -0.3000 -0.0030 -0.3030

81.6123 0.2618 0.0030 0.2648 -0.2180 -0.0030

-0.0865

73.2246 0.2328 0.0032 0.2360 -0.1462 -0.0032 -0.1494

64.8370 0.2105 0.0036 0.2141 -0.0829 -0.0036

0.0153

56.4493 0.1932 0.0043 0.1975 -0.0274 -0.0043 -0.0317

48.0616 0.1798 0.0053 0.1852 0.0207 -0.0053

0.0836

39.6739 0.1695 0.0073 0.1768 0.0614 -0.0073 0.0541

31.2862 0.1618 0.0110 0.1727 0.0946 -0.0110

6.1232 0.1504 0.2599 0.4103 0.1479 -0.2599 -0.1120

0.0909

22.8986 0.1562 0.0195 0.1757 0.1202 -0.0195 0.1007

14.5109 0.1524 0.0471 0.1995 0.1380 -0.0471

.: Effective Weight of Lantern = WL 13.93 kn

Meridonial Stresses (N/mm2)Meridonial Stresses (N/mm2)Meridonial Stresses (N/mm2)Meridonial Stresses (N/mm2) Hoop Stresses (N/mm2)Hoop Stresses (N/mm2)Hoop Stresses (N/mm2)Hoop Stresses (N/mm2)

Due to wDue to wDue to wDue to w Due to WLDue to WLDue to WLDue to WL TotalTotalTotalTotal Due to wDue to wDue to wDue to w Due to WLDue to WLDue to WLDue to WL TotalTotalTotalTotal

Weight of Lantern 22.00 kn

Weight of Dome Shell CPD 8.07 kn

Live Load 1.500 kn/m2

Total = w 4.000 kn/m2

= 90.0000 deg Self Wt of Dome Structure = 2.500 kn/m2

sin = AB / (2 * r) 1.0000 Thickness of Dome = 100 mm

= 6.1232 deg

cos = 0.9943

7.50 7.50

sin = cd / (2 * r) 0.1067

CD = Diameter of opening = 1.60 m

PQ = rise of opening = h 0.04 m

Rise PS 7.50 m

.: Radius of Dome r = AO = 7.50 m

Steel Grade fy allowable 140 n/mm2 7.50

Diameter of Dome base AB = 15.00 m

Geometry of Dome :Geometry of Dome :Geometry of Dome :Geometry of Dome :

Table 1Table 1Table 1Table 1

Concrete Grade fc' 15 n/mm2

7.5

0

m (modular ratio) 18

Ref Calculation Output

note : Enter Data in cells marked only

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Subject : Description :

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cont'd :

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Job no : Sheet No :

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This program Designs and

Optimises RCC Domes

Written and programmed by

:-

A B Quadri

www.abqconsultants.com

[email protected]

[email protected]

9959010210

9959010211h

4)4)4)4)

knknknkn

==== ---- xxxx 2222 xxxx xxxx

==== knknknkn

Thus the Hoop Stresses due to self weight swt will be decreased in a ratio Thus the Hoop Stresses due to self weight swt will be decreased in a ratio Thus the Hoop Stresses due to self weight swt will be decreased in a ratio Thus the Hoop Stresses due to self weight swt will be decreased in a ratio ====

while the Hoop Stresses due to weight of lantern WL will be increased by while the Hoop Stresses due to weight of lantern WL will be increased by while the Hoop Stresses due to weight of lantern WL will be increased by while the Hoop Stresses due to weight of lantern WL will be increased by ====

The Results are Tabulated below.The Results are Tabulated below.The Results are Tabulated below.The Results are Tabulated below.

Table 3Table 3Table 3Table 3

to

5)5)5)5)

.: Maximum Hoop Tensile Stress per meter length of

meridian = x x

= N

.: Area of Steel = =

Temperature Steel = x x

=

use mm @

Hence Provide mm @

In Portion where no Hoop Tension is developed In Portion where no Hoop Tension is developed In Portion where no Hoop Tension is developed In Portion where no Hoop Tension is developed

provide 0.15 % reinforcementprovide 0.15 % reinforcementprovide 0.15 % reinforcementprovide 0.15 % reinforcement =

use mm @

Hence Provide mm @

mm c/c

8 300 mm c/c ok


90.0000 -0.1875 -0.0036 -0.1911

8 335335335335

mm c/c ok

81.6123 -0.1363 -0.0037 -0.1400 150150150150 mm2 / m

mm2 / m

8 162162162162 mm c/c

73.2246 -0.0914 -0.0039 -0.0953

8 160

64.8370 -0.0518 -0.0044 -0.0562

.: Total Reinforcement : = 310

100 1000

56.4493 -0.0171 -0.0052 -0.0223

100

150150150150 mm2 / m

48.0616 0.0129 -0.0065 0.0064

140140140140

0.15

1000

39.6739 0.0384 -0.0088 0.0295

-22389.11

22389223892238922389 160160160160 mm2 / m

31.2862 0.0591 -0.0133 0.0458 -0.2239 100

n/mm2 Safe

22.8986 0.0751 -0.0238 0.0514

Maximum Hoop Tensile Stress =Maximum Hoop Tensile Stress =Maximum Hoop Tensile Stress =Maximum Hoop Tensile Stress = -0.2239-0.2239-0.2239-0.2239 n/mm2

14.5109 0.0862 -0.0573 0.0289

Maximum Compressive Stress =Maximum Compressive Stress =Maximum Compressive Stress =Maximum Compressive Stress = 0.41030.41030.41030.4103

-0.2239 n/mm2

6.1232 0.0924 -0.3163 -0.2239

Provision of Reinforcement :Provision of Reinforcement :Provision of Reinforcement :Provision of Reinforcement :

13.93513.93513.93513.935

Hoop Stresses (N/mm2)Hoop Stresses (N/mm2)Hoop Stresses (N/mm2)Hoop Stresses (N/mm2) Thus we see that the maximum hoop tension at the opening

Due to wDue to wDue to wDue to w Due to WLDue to WLDue to WLDue to WL TotalTotalTotalTotal

has been increased from -0.1120 n/mm2

16.95916.95916.95916.959

250250250250 0.6250.6250.6250.625

400400400400

16.95916.95916.95916.959 1.2171.2171.2171.217

increasing the Live Load.increasing the Live Load.increasing the Live Load.increasing the Live Load.

self wt =self wt =self wt =self wt = 2.52.52.52.5

.: Effective Weight of Lantern = WL 22.0022.0022.0022.00 2.52.52.52.5 7.57.57.57.5 0.0430.0430.0430.043

Hoop Stress in absence of Live Load :Hoop Stress in absence of Live Load :Hoop Stress in absence of Live Load :Hoop Stress in absence of Live Load :

Hoop Stress in absence of Live Load this will increase the Tensile Stress in the upper portion of theHoop Stress in absence of Live Load this will increase the Tensile Stress in the upper portion of theHoop Stress in absence of Live Load this will increase the Tensile Stress in the upper portion of theHoop Stress in absence of Live Load this will increase the Tensile Stress in the upper portion of the

Dome, specially near the periphery of the opening. However, meridonal thrust will not increase by Dome, specially near the periphery of the opening. However, meridonal thrust will not increase by Dome, specially near the periphery of the opening. However, meridonal thrust will not increase by Dome, specially near the periphery of the opening. However, meridonal thrust will not increase by

Project :



Revision note :



Job no : Sheet No :

cont'd :

6)6)6)6)

Meridonal Thrust per Meter length of the Dome at it's Base =Meridonal Thrust per Meter length of the Dome at it's Base =Meridonal Thrust per Meter length of the Dome at it's Base =Meridonal Thrust per Meter length of the Dome at it's Base = x x

=

Horizontal component T per unit length :Horizontal component T per unit length :Horizontal component T per unit length :Horizontal component T per unit length : = x = n/m

.: Hoop Tension trying to rupture the Beam :.: Hoop Tension trying to rupture the Beam :.: Hoop Tension trying to rupture the Beam :.: Hoop Tension trying to rupture the Beam : = x = n

.: Area of Steel = = use mm

As = >

mm

Equivalent area of composite section of Beam of area of cross-section of area A :

= A + (m - 1)*Ast = A + 18 x x

= A +

Allowing Tensile Stress of in composite section, we have =

( A + )

A conc = .: Provide a Ring Beam size x

Area = >

mm

mm @ mm c/c

Note : Ring Beam is assumed

to be continously supported by

concrete wall from below.

200


Stirrups 6 160 ok

20

0

Ring BeamRing BeamRing BeamRing Beam

ok

Hence Provide Rings 10 6 nos ok

8482

Solving From which we get

-8482 mm2 200 200

40000 mm2 -8482

78.5 6

8482

1.2 n/mm2 1.2

ok

Hence Provide Rings 10 6 nos ok

0

1111 nos

140140140140 79 mm2 0 mm2

0 15 0

2

0000 0000 mm2 / m 10

30296 n/m

30296 cos 90.00 0


Design for Lower Ring Beam :Design for Lower Ring Beam :Design for Lower Ring Beam :Design for Lower Ring Beam :

0.3030 100 1000

Project :



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15 Design of RCC Dome 23052014