Annular Raft

DESIGN OF ANNULAR RAFT : 1. Materials : Grade of Concrete

=

25 @mm2

Grade of Steel ;oion rario ( μ)

= =

415 @mm2 0.3

c

"

a

p = P/A

p' = M/Z

2. Size of Raft : Central Diameter of Raft (2C) Depth of o!ndation a"o#e raft Depth of Raft %nit&ei'ht of Concrete

= = = =

4.80 2.00 0.$0 25

m m m 

Safe "earin' capacit* %nit&ei'ht of Soil +ei'ht of tan +ind moment Shear at -ae D!e to +ind +idth of Raft +idth of col!mn Depth of col!mn o. of col!mn ternal Diameter of Raft (2a) nternal Dia meter of Raft (2")

= = = = = = = = = = =

200 18 3200 148 1./ 1.8 0.50 0.50 4 $.$00 3.000

rea of Raft ( )

=

2.14 m2

Section 6od!l! of Raft (7)

=

2.02 m3

= = = =

$10.$5  /88.0/2   4798.74  151.23 ,m

@mm2   ,m  m m m no m m

3. Calculation of Section Properties Properties :

 4. Calculation Calculation of Loads (Self weigt weigt !Soil" : actored Self &ei'ht of raft actored of &ei'ht of oil a"o#e raft  otal  otal actored actored 9ertical 9ertical :oad on Raft Raft (;)  otal  otal actored actored 6oment at Raft Raft (6) #. Calculation of Stresses on Soil : 6a. Stre

=

; 

=

= =

!"#$" O% 

6 7

182.411 @m2

= 6in. Stre

<

; 

,

 = 1.5 > S-C = 3. @m 2

6 7

171.217 @m2

? 0.0

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$. Calculation %ending Mo&ents and Sears : a. 'ue to ertical Load: =

p = P/A

17&.814 @m2

For , r < c

6r1 =

p > a2 $4

 4 > (3 a2 $4

 4 > (1a 2

, 1$ >α2 (1α2 (3(1α2 (1α2 > (1(1 ( 1 < α2 )* (3+μ)

8 > α4 * log α

,

(1 α2 * (3 + μ)

1, α

1, α

2

3.3 1.5 2.4 1.5

= = =

0.455 0.2 0.455

F 1

=

,1.$0

F 2

=

,/./4

p > a2 $4

=

30.08$

 4 > (3α2 > (1α2 > (3(1 α 2 *

(1+ μ) * (1 + log β)

(1 , A)

 , 8 > α2 > β2

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Er =

p>a 1/2 F 3 =

2 > ρ2 + 8  > F 3 , 2 * K 5 * ρ-1

3 β

F 4 =

,

3 > β2  (1-μ)

2

α4

8> 1 <

(3 < μ

3 > β2 *α 4 , 3 > α4 * (3+μ) β

* (2 + μ)

1 < α (3 + μ) ,

8>

>

α4 2

(

2

F 5 =

  ,

1< α

(2 < A) (1 - μ)

12 > α4 F 3

=

,0.438

F 4

=

,2.004

F 5

=

0.512

p > a2 1/2

=

0.31

 4 > (5 (3 (1,μ) * K 4* ρ-3

=

,2/.8$/

 (1 (1(1d 100.000 HHH 1800.0 1800.000 00  540. 540.00 00 0.323 J

Table-19 of IS:4!-"###:

τc

pt 0.25 0.5

0.23 0.31

;ermii"le Shear tre ( τc

=

!"#$" O% 

.253 @mm 2

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DESIGN OF ANNULAR RAFT : 1. Materials : Grade of Concrete

=

25 @mm2

Grade of Steel ;oion rario (μ)

= =

415 @mm2 0.3

"

c

a

p = P/A

p' = M/Z

2. Size of Raft : Central Diameter of Raft (2C) Depth of o!ndation a"o#e raft Depth of Raft %nit&ei'ht of Concrete

= = = =

4.80 2.00 0.$0 25

m m m 

Safe "earin' capacit* %nit&ei'ht of Soil +ei'ht of an +ind moment Shear at -ae D!e to +ind +idth of Raft ternal Diameter of Raft (2a) nternal Dia meter of Raft (2") +idth of col!mn Depth of col!mn o. of col!mn

= = = = = = = = = = =

200 @mm2 18  3200  148 ,m 1./  1.8 m $.$00 m 3.000 m 0.50 m 0.50 m 4 no

rea of Raft ( )

=

2.14 m2

Section 6od!l! of Raft (7)

=

2.02 m3

= = = =

$10.$5  /88.0/2   4798.74  151.23 ,m

=

17&.814 @m2

3. Calculation Calculation of Section Properties Properties :

 4. Calculation of of Loads (Self weigt !Soil" !Soil" : actored Self &ei'ht of raft actored of &ei'ht of oil a"o#e raft  otal  otal actored actored 9ertical 9ertical :oad on Raft Raft (;)  otal  otal actored actored 6oment d!e to &ind at Raft (6) #. Calculation %ending Mo&ents and Sears : a. 'ue to ertical Load: p = P/A For , r $ c

6r2 =

p > a2 $4

 4 > (3α2 (1 (3(1 a2 $4

 4 > (1α2 (1(1(1a

 ( ρ , ρ-1 )

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where

F1 =

F 1 < 8 >( 1 < log β ) * ( 1 - α2 )

F2=

F 2 , ( 8 > β2 ) * ( 1 - α 2 )

B!ter radi! of raft (a) nner radi! of raft (") Centre line radi! of raft (c) Radi! of re!ired moment from centre(r)

= = = =

3.3 1.5 2.4 3.3

= = =

0.455 0.2 1.000

F1

=

3.10

F2

=

,13.331

p > a2 $4

=

30.08$

 4 > (3< μ) * ρ2

=

13.200

1$ > (1 (3(1 t " >d 100.000 HHH 1800.0 1800.000 00  540 540.00 .00 0.323 J

Table-19 of IS:4!-"###:

τc

pt 0.25 0 .5

0.23 0.31

;ermii"le Shear tre ( τ

=

!"#$" O% 

.253 @mm2