Raft+foundation_

DESIGN OF RAFT FOUNDATION

Name of Pr Project :

Design Example 18.5, Page 561, Reinf co concrete A.K.ain

Given Data:

1 !ra"e of #teel

$e

%15

& !ra"e of 'oncrete

(

15

) #i*e of 'ol+mn

- x /

)00

% #afe earing 'apacit2 of #oil

65.00

mm

Along -3"irection/

&0

mm

6 Di Diameter of ars

Along 3"irection/

&0

mm

2 



3

)00

mm

KN>m&

5 Di Diameter of ars

1

-

4 

C

C 

B

B

-

 A

A

O

1

2

3

4

Details of Columns

'onsi onsi" "erin ring col+ col+m mn A31 A31 as orig rigin 4 4/

Column

(omen ment ao ao+ +t -3a -3ax xis oment a o+t 3ax s

X-cord Y-cord (in m) (in m)  A31 0 0  A3&  0  A3) 1% 0  A3% &1 0 31 0 6 3&  6 3) 1% 6 3% &1 6 '31 0 1& '3&  1& '3) 1% 1& '3% &1 1& 'antile9er lengt; from centre line of col+mns
Load (KN) 550 1&00 1&00 550 600 &000 &000 1&00 500 1500 1500 500

(x clo cloc7 c7ise ise 9e 2 nt c oc 39 3 9e

Moment My Moment Mx (KN-m) (KN-m) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.) 0.)

m m

To Run the Program Pre ! Ctrl"# $

 

=otal ?etical 'ol+mn
P @

1))00

KN

%ccentricity along x-direction =aing moment of col+mn forces ao+t t;e gri" 131 x @ 10.% m ex @ 10.% 3 10.5 @ 0.%% m %ccentricity along y-direction =aing moment of col+mn forces ao+t t;e gri" A3A 2 @ 6.&&6 m e2 @ 6.&&6 3 6

Bx

B2

 A

@

0.&&6

@

&1.6

m -

@

)600.68

@

1&.6

1&.6 ) 1& m%

-

&1.6 )

@

1& m% 10581.58

@ @

1&.6 &&.16

&1.6 m&

(xx  @

P.e2

@

)000.00

KNm

(22  @

P.ex

@

6)00.00

KNm

P>A @

KN>m&

%8.8

#oil press+re at "ifferent points is as f ollo7s

σ

@

P  A

(22



B2

.x



(xx Bx

.2

Corner C-4

σ'3%

@

%8.8

@ @

%8.8 60.5%

@ @

%8.8 50.0%

@ @

%8.8 %.68

6)00.00 10581.58  6.%)0 KN>m& 

10.8





5.&%

6.%)0

3

5.&%

6.%)0



5.&%

Corner A-4

σ A3%

 &

KN>m

Corner C-1

σ'31

3 KN>m&

)000.00 )600.68

6.)

Corner A-1

σ A31

@ @

%8.8 ).18

@ @

%8.8 55.&8

@

%8.8

6.%)0 3 & KN>m

3

5.&%

6.%)0

3

0.000

6.%)0

3

0.000

Grid B-4

σ3%

 KN>m&

Grid B-1

σ31

@

%&.%)8

3 &

KN>m

60.5% KN>m&  ence 4K Bn t;e -3"irection, t;e raft is "i9i"e" in t;ree strips :3 (axim+m #oil Press+re @

(i)

&tri' C-C i"t; #oil Press+re #pan (axim+m moment

@ @ @ @ @

(ii)

&tri' - i"t; #oil Press+re #pan (axim+m moment

(axim+m moment

60.5% &6.68

@ @

6 5.&) .00

@ @ @

(iii) &tri' - i"t; #oil Press+re #pan

).) 60.5% .00

5.&) &8).8&

@ @

).) 5&.6% .00

@ @ @

5&.6% &58.10

C

65.00

KN>m&

65.00

KN>m&

m KN>m& m -

 10

&

 10

&

 10

&

0.) &

&

KNm>m

m KN>m& m KNm>m

m KN>m& m KNm>m

'antile9er (oment along -3"irection #oil Press+re #pan (axim+m moment

@ @ @ @

(iii) &tri'

60.5% 0.)0 60.5% &.&

KN>m& m KNm>m

*-*

(axim+m #oil Press+re @ #pan @ (axim+m moment

@ @

60.5% 6 m 60.5%

&&.%6

KN>m& 

KNm>m

6 8

C &

'antile9er (oment along -3"irection #oil Press+re #pan

@

60.5% 0.)0

@

(axim+m moment

@ @

KN>m& m

60.5% &.&

0.) &

-

&

KNm>m

=;erefore, (axim+m $actore" en"ing (oment
"

@

%%5.0&

@

0.1)8

@

%0

KNm>m

σc "& mm

Chec+ ,or Punching &hear 
81

mm s τc

#;ear #trengt; of 'oncrete @ s ;ere @ 0.5 

βc =;erefore

#;ort "imension of col+mn
@

s

@

τc

@ @

βc @

1

1 0.&5

√σc N>mm& N>mm&

0.

ence, #;ear #trengt; of 'oncrete

0. N>mm&

@

$or 'orner 'ol+mn Perimeter

o

@ @

Nominal #;ear #tress

85 11

τ9



85 mm ?+

@

o"

@



@

0.5

0



0



0

8&5000 1%010 N>mm&

$or #i"e 'ol+mn Perimeter

o

@ @

Nominal #;ear #tress

111 &8)

τ9

@ @

τ9

3

=;erefore effecti9e "ept; reF+ire"  A"opt effecti9e "ept; 49erall "ept;

τc

@ @ @ @



85 mm ?+ o" 0.



@

85

&&50000 &)&&6 N>mm&

0.00 N>mm& ence Effecti9e "ept; is 4.K. 81 mm 8&0 mm 860 mm

.e/elo'ment Length 

De9elopment lengt; < " 7;ere, =;erefore,

τ" @

@

1.6

0.8 σ2 φ % τ" x

1.0

@ 56 φ &0 mm ars along -3"irection/ <" @ 11&0

mm

&0 mm ars along 3"irection/ <" @ 11&0

mm

@

1.6

<"

$or

$or

Rein,orcement in long direction (

@

%.%5E08 .805

0.8 σ2 Ast " 3 σ A >σc/ 2 st )61.05  Ast 

@  Ast&

3

&6061  Ast

 Ast

@

1588

(inim+m reinforcement reF+ire" =;erefore area of steel reF+ire" Pro9i"e

&0 mm φ ars H

8&0

3



0.0&6 Ast /

%.%5E08

@

0

mm&>m @ @

0.1&G 10)&

mm&>m

@

1588

mm&>m

&00

mm '>' in long "irection At top an" ottom/

Rein,orcement in hort direction (

@

%.0E08 .805

0.8 σ2 Ast " 3 σ A >σc/ 2 st )61.05  Ast 

@  Ast&

3

&6061  Ast

 Ast

@

1%5&

(inim+m reinforcement reF+ire" =;erefore area of steel reF+ire" Pro9i"e

&0 mm φ ars H

8&0

3



0.0&6 Ast /

%.0E08

@

mm&>m @ @ @

&&0

0.1&G 10)& 1%5&

mm&>m mm&>m

mm '>' in s;ort "irection At top an" ottom/

0

DRAWING

&1.60

&0

mm φ arsH

&00 mm c>c

top I ottom/

        0         6   .         &         1

&0

mm φ ars H

&&0 mm c>c

top I ottom/

&0 mm φ arsH

&00 mm c>c

&0 mm φ arsH

&&0 mm c>c

        0         6         8   .         0

Note : 1/ All "imension in m 7;ere not specifie"  &/ Dra7ing not to scale

(Rein,orcement .etail)

DRAWING

&1.60

&0

mm φ arsH

&00 mm c>c

top I ottom/

        0         6   .         &         1

&0

mm φ ars H &&0 mm c>c top I ottom/

&0 mm φ arsH

&00 mm c>c

&0 mm φ arsH

&&0 mm c>c

        0         6         8   .         0

Note : 1/ All "imension in m 7;ere not specifie"  &/ Dra7ing not to scale

(Rein,orcement .etail)