Raft Design

PROPOSED RRI BUILDING AT VPT

STRUCTURAL DESIGN OF RCC RAFT FOUNDATION

Calculation of CG of loads in both principal directions

29 734.0037 406.0034 476.0035 536.00

TOTAL 2152.00

Description of step P*X

Sum of Col loads of Column line A1 476 0 0.00Sum of Col loads of Column line A2 536 2.14 1147.04Sum of Col loads of Column line A3 1140 2.98 3397.20

Total 2152 4544.24 x = ΣP*A/ΣPˉ 2.11

p*Y

Sum of Col loads of Column line B1 734 0 0.00Sum of Col loads of Column line B2 1012 1.3 1315.60Sum of Col loads of Column line B3 406 3.1 1258.60

Total 2152 2574.20y = ΣP*A/ΣPˉ 1.20

Safe bearing capacity of soil 200AREA of Slab required ( considering 15% more for self Wt) 16.50 sqm

Length of slab provided along 'a' direction 6.33Length of slab available between a1 and a3 ref li 2.98Distance of CG of loads from left ref line(A1) = 2.112 m

Distance of CG of loads from rigth ref line(A5) = 0.868 m

Providing 0.75m offset onl sidef of line A1Half the Length of slab provided =2.12+0.75 2.862 m

Off set required on right side of a3 1.993 6.54Total length of slab required along 'a' direction 5.72 m

Length of slab available between 1 and 3ref lines alonbg 'y' directi 3.3Distance of CG of loads from ref line(b1) = 1.196 m

Distance of CG of loads from ref line(b3) = 2.104 m

Providing 0.75m offset from line b3Half the Length of slab provided =2.10+0.75 2.854 m

Off set required on left side of ref.line b1 1.658 5.43Total length of slab required along 'b' direction 5.71 m

#REF!

Column Number

DESIGN LOAD INCLUDING

IMPACT FACTOR (kN)

Column LoadP (kN)

X' from Ref line

(m)

Column LoadP (kN)

Y' from Ref line

(m)

kN/m2

2030 600

600cg lin

eof

load

s

9002

8939

15377

1890 4800 3887 4800

4439

C1 C2 C3 C4 C5

C6 C7 C8 C9 C10

C11 C12 C13 C14

4500

CENTER LINE DRAWING

C15

A1

A

B1B

6974

10577

8939

A2A3 A4 A5

B2

B3

1013

9

8403

9002

17407

716

600

Length of slabh provided 'L' L 6.00Area of slab available = 18 * 10.14 #REF! sqm

Total column loads P 2152Uniform Intensity of upward soil pressure p' #REF! kN/sqm

Contd on page 2

Description of step Parameter Value UnitShort span of larger panel Lx 4.5 m

Long span of larger panel Ly 4.8 m

Cantilever projection at left edge lc 2.023BM for equivalent beam f = p*lx^2/12 #REF! kNm

Factored BM #REF! kNm

Cantilever BM at left edge = p*lc^2/2 #REF! kNm


Max Factored BM Mu #REF!

kNm

Design coefficients

fck ( For M30 Grade of Concrete) 30fy ( For Fe415 Grade of Steel) 415Clear cover for bottom of concrete 50 mm

Considering im length of slab, b = 1000 mm

#REF! mm

Over all depth provided D 600 mm

Actua effective depth available d 545 mm

Dia of main reinforcement bar proposed 10 mm

Area of steel required Ast #REF!Min. steel required @ 0.12% of GCA 720

Area of Steel to be provided #REF!

Area of 10 mm bar 78.54Spacing of 10 mm bars #REF! mm c/c

Max spacing 180 mm c/c

Spacing to be provided #REF! mm c/c 100.00 mm c/c

Area of steel provided Ast 785.40p% steel provided

pt 0.13Check for Punching Shear

Max Column Load 680 kN

Factored Load 1020 kN

Check for two way ShearWidth of column 300 mm

Breadth of Column 230 mm272.5 mm

Width of Critical Section 845 mm

0.845 mm

Breadth of critical section 775 mm

Since the area of slab provided over the full building dimensions, is quite larger than required

from SBC creterion, the slab can be designed as an equivalent beam for a uniform BM of ( wl2/12 ), in both directions and at top & bottom layers.

Design of slab page 2

N/mm2

Mu = Qbd^2 = 0.138*fckbd2

Effective depth required = d = sqrt(Mu/(0.138*fck*b))

mm2

mm2

mm2

mm2

How ever provide 10 mm bar @.. Bothways at top & bottom matsOR 12mm

# @ 150 mm c/c may be

provided

mm2

critical section is at d/2 from the face of the column

Breadth of critical section0.775

Net Punching Load 'Vu' #REF! kN

Depth of critical section = dc 545 mm

Perimeter of critical section 1551.69mm




15 102016 98631 119532 122422 17523 17527 17528 175

TOTAL 5125


Sum of Col loads of Column line A1 2215 0 0Sum of Col loads of Column line A2 350 1.3 455Sum of Col loads of Column line A3 350 3.1 1085Sum of Col loads of Column line A4 1224 3.47 4247.28Sum of Col loads of Column line A5 986 4.2 4141.2

Total 5125 9928.48 x = ΣP*A/ΣPˉ 1.937

p*Y

Sum of Col loads of Column line B1 2006 0 0Sum of Col loads of Column line B2 350 1.3 455Sum of Col loads of Column line B3 350 3.1 1085Sum of Col loads of Column line B4 2419 4.4 10643.6

Total 5125 12183.6y = ΣP*A/ΣPˉ 2.38


Length of slab provided along 'y' direction 6.33Length of slab available between left and right ref lines 4.2Distance of CG of loads from left ref line(A1) = 1.937 m


Providing 0.90m offset on right side of line A5Half the Length of slab provided =2.263+0.9 3.163 m

Off set required on left side of slab 1.225Total length of slab required along 'a' direction 6.33 m

Length of slab available between 1 and 4 ref lines alonbg 'y' direct 4.58Distance of CG of loads from ref line(b1) = 2.377 m

Distance of CG of loads from rigth ref line(b4) = 2.203 m

Providing 0.90m offset from line b1Half the Length of slab provided =2.38+0.9 3.277 m

Off set required on left side of slab 0.900Total length of slab required along 'b' direction 6.55 m

Column Number


IMPACT FACTOR (kN)

Column LoadP (kN)

X' from Ref line

(m)

Column LoadP (kN)

Y' from Ref line

(m)

kN/m2

2030 600

600cg lin

eof

load

s

9002

8939

15377

1890 4800 3887 4800

4439

C1 C2 C3 C4 C5

C6 C7 C8 C9 C10

C11 C12 C13 C14

4500

CENTER LINE DRAWING

C15

A1

A

B1B

6974

10577

8939

A2A3 A4 A5

B2

B3

1013

9

8403

9002

17407

716

600

#REF!

Length of slabh provided 'L' L 6.00Area of slab available = 18 * 10.14 #REF! sqm

Total column loads P 5125Uniform Intensity of upward soil pressure p' #REF! kN/sqm

Contd on page 2

Description of step Parameter Value UnitShort span of larger panel Lx 4.5 m


Cantilever projection at left edge lc 2.023BM for equivalent beam f = p*lx^2/12 #REF! kNm


Cantilever BM at left edge = p*lc^2/2 #REF! kNm


Max Factored BM Mu #REF!

kNm

Design coefficients



#REF! mm




Area of steel required Ast #REF!Min. steel required @ 0.12% of GCA 720

Area of Steel to be provided #REF!

Area of 10 mm bar 78.54Spacing of 10 mm bars #REF! mm c/c


Spacing to be provided #REF! mm c/c 100.00 mm c/c

Area of steel provided Ast 785.40p% steel provided

pt 0.13Check for Punching Shear

Max Column Load 680 kN





0.845 mm


Since the area of slab provided over the full building dimensions, is quite larger than required

from SBC creterion, the slab can be designed as an equivalent beam for a uniform BM of ( wl2/12 ), in both directions and at top & bottom layers.


N/mm2



mm2

mm2

mm2

mm2

How ever provide 10 mm bar @.. Bothways at top & bottom matsOR 12mm

# @ 150 mm c/c may be

provided

mm2


Breadth of critical section0.775

Net Punching Load 'Vu' #REF! kN


Perimeter of critical section 1551.69mm

APARTMENT FOR SONA SUJAN AT BERHAMPURM20 SBC 200

JOINT COLUMNS LOADS STEEL COL SIZE

2 42 817 2981 230 x 450 2-25 + 6-20# 904 7.31 7'6" X 7'6"5 39 842 2815 230 x 450

45 19 904 2662 230 x 450

23 30 785 2484 230 x 450 8-20# 845 7.07 7'6" X 7'6"53 13 845 2236 230 x 450

55 1 747 2185 230 x 450 4-20+4-16# 786 6.82 7' X 7'43 17 786 1908 230 x 45027 24 749 1822 230 x 45044 18 773 1822 230 x 450

48 8 656 1220 230 x 450 8-16# 656 6.23 6' 6" X 6'6"4 38 558 1008 230 x 4506 40 605 1097 230 x 4501 41 593 1490 230 x 4503 43 577 1445 230 x 450

70 7 569 1078 230 x 450 4-16+4-12# 611 6.01 6' X 6'54 14 570 766 230 x 45047 21 611 887 230 x 450

52 12 1209 3591 230 x 600 8-20+2-25# 1209 8.45 8'6" X 8'6"50 10 1196 3488 230 x 600

22 33 1048 2760 230 x 600 8-20+2-16# 1072 7.96 8' X 8'29 26 1072 2760 230 x 60046 20 1060 2652 230 x 600

56 2 1332 2650 230 x 600 4-25+6-20# 1332 8.87 9' X 9'63 5 1266 4035 230 x 60059 3 1267 4021 230 x 60061 4 1290 2429 230 x 600

8 36 1254 3968 230 x 600

65 6 1094 2981 230 x 600 8-20+2-16# 1094 8.04 8' X 8'49 9 1008 2208 230 x 60028 25 954 2559 230 x 60051 11 981 2098 230 x 600

combined footing CF1

COL STEEL PROVIDED

Design Load

Footing area

requiredFooting size

provided

25 27 175 235 230 x 300 8-12# 175 3.2226 28 175 235 230 x 30032 22 175 235 230 x 30034 23 175 235 230 x 300

36 15 1020 2318 230 x 600 6-20+4-16# 1020 7.7738 16 986 2208 230 x 600

20 31 1195 3455 230 x 600 4-25+6-20# 1224 8.5121 32 1224 4000 230 x 600

combined footing CF2

9 34 476 639 230 x 450 8-16# 536 5.6319 35 536 721 230 x 450

847 29 734 658 230 x 450 4-16+4-12# 734 6.597 37 406 575 230 x 450

COMBINED FOOTING

COMBINED FOOTING

COMBINED FOOTING

COMBINED FOOTING

COMBINED FOOTING

D1 = D2 Mat Steel

13" 12# @ 5" c/c

13" 12# @ 5" c/c

12" 12# @ 5" c/c

11" 12# @ 6" c/c

10" 10# @ 4" c/c

14" 12# @ 5" c/c

13" 12# @ 5" c/c

15" 12# @ 4" c/c

13" 12# @ 5" c/c

8" 10# @ 5" c/c

8" 10# @ 5" c/c

8" 10# @ 5" c/c

8" 10# @ 5" c/c

8" 10# @ 5" c/c


59 1 67 84 230 x 230 272 4-12#

35 6 122 153 230 x 230 685 4-16#

85 15 82 103 230 x 230 611

9 2 280 350 230 x 300 1179 4-16+4-12#

10 3 365 456 230 x 300 327

11 4 311 389 230 x 300 1016

12 5 107 134 230 x 300 1017

1 11 279 349 230 x 300 12062 12 355 444 230 x 300 580

3 13 304 380 230 x 300 968

4 14 109 136 230 x 300 1034

5 7 458 573 230 x 300 637 8-12#

8 10 203 254 230 x 300 776

6 8 544 680 230 x 300 543

7 9 500 625 230 x 300 448

Total 40865110

Calculation for depth of Foundation

1 Max Column Load 680 kN2 Soil Angle of Repose (φ) 30 Degrees

0.52 radians

3 Bulk Density (w) 17

4 Max SBC (p) 150

5 Min. Depth of Foundation, using Rankine Formula

0.98 m

6 2.5 m

7 2.15 m

Statement showing the Aanalysis results and Design details of Columns

JOINTS NO.

COLUMN NOS

WORKING LOAD(KN)

DESIGN LOAD INCLUDING IMPACT FACTOR of 1.25 (kN)

COLUMN SIZEmm

COLUMN STEEL

REQUIRED(mm2)

COLUMN STEEL PROVIDED

(BARS)

kN/m3

kN/m2

p{(1-sinφ)/(1+sinφ)}2w

Max. Depth of foundation suggested in Soil Report

Depth of Foundarion provided,including sand cushion and pcc levelling course


59 1 67 84 230 x 230 272

9 2 280 350 230 x 300 1179

10 3 365 456 230 x 300 327

11 4 311 389 230 x 300 1016

12 5 107 134 230 x 300 1017

35 6 122 153 230 x 230 685

5 7 458 573 230 x 300 637

6 8 544 680 230 x 300 543

7 9 500 625 230 x 300 448

8 10 203 254 230 x 300 776

1 11 279 349 230 x 300 1206

2 12 355 444 230 x 300 580

3 13 304 380 230 x 300 968

4 14 109 136 230 x 300 1034

85 15 82 103 230 x 230 611

Statement showing the Aanalysis results and Design details of Columns

JOINTS NO.

COLUMN NOS

WORKING LOAD(KN)

DESIGN LOAD INCLUDING IMPACT FACTOR of 1.25 (kN)

COLUMN SIZEmm

COLUMN STEEL

REQUIRED(mm2)

Total 40865110




1 842 3503 4564 3895 1346 1537 5738 6809 625

10 25411 34912 44413 38014 13615 103

TOTAL 5110


Sum of Col loads of Column line A 340 0 0Sum of Col loads of Column line A 1272 1.89 2404.08Sum of Col loads of Column line A 1580 6.69 10570.2Sum of Col loads of Column line A 1394 10.577 14744.338Sum of Col loads of Column line A 524 15.377 8057.548

Total 5110 35776.166 x = ΣP*A/ΣPˉ 7.001

p*Y

Sum of Col loads of Column line B 1413 0 0Sum of Col loads of Column line B 2285 4.44 10145.4Sum of Col loads of Column line B 1412 8.94 12623.28

Total 5110 22768.68y = ΣP*A/ΣPˉ 4.46


providing minimum offset of 0.60m alround,Width of slab available 10.14 m

Length of slab available between left and right ref lines 15.377Distance of CG of loads from left ref line(A1) = 7.001 m


Providing 0.60m offset on right side of line A5Half the Length of slab provided =8.403+0.60 8.976 m

Off set required on left side of slab 1.975Total length of slab required 17.95Length of slabh provided 'L' L 18.00Area of slab available = 18 * 10.14 182.52 sqm

Total column loads P 5110Uniform Intensity of upward soil pressure p' 28.00 kN/sqm < SBC,Adequate

Column Number


IMPACT FACTOR (kN)

Column LoadP (kN)

X' from Ref line

(m)

Column LoadP (kN)

Y' from Ref line

(m)

kN/m2

Since the area of slab provided over the full building dimensions, is quite larger than required from SBC creterion, the slab can be designed as an equivalent beam for a uniform BM of

( wl2/12 ), in both directions and at top & bottom layers.

2030 600

600cg lin

eof

load

s

9002

8939

15377

1890 4800 3887 4800

4439

C1 C2 C3 C4 C5

C6 C7 C8 C9 C10

C11 C12 C13 C14

4500

CENTER LINE DRAWING

C15

A1

A

B1B

6974

10577

8939

A2A3 A4 A5

B2

B3

1013

9

8403

9002

17407

716

600

Contd on page 2

Description of step Parameter Value Unit

Short span of larger panel Lx 4.5 m


Cantilever projection at left edge lc 2.023BM for equivalent beam f = p*lx^2/12 47.24 kNm

Factored BM 70.87 kNm

Cantilever BM at left edge = p*lc^2/2 57.29 kNm

Factored BM 85.93 kNm

Max Factored BM Mu 85.93 kNm

Design coefficients



144.07 mm




Area of steel required Ast 364

Min. steel required @ 0.12% of GCA 720

Area of Steel to be provided 720

Area of 10 mm bar 78.54Spacing of 10 mm bars 109.08 mm c/c


Spacing to be provided 109.08 mm c/c 100.00 mm c/c

OR 12mm # @ 150 mm c/c may be providedArea of steel provided Ast 785.40p% steel provided pt 0.13

Check for Punching ShearMax Column Load 680 kN





0.845 mm


0.775Net Punching Load 'Vu' 1019.96 kN


Perimeter of critical section 1551.69 mm

Actual punching shear stress τ v 1.21Calculation of Design Shear strength=Ksτ c

βc = B/L of Column dimensions 0.77Ks = min of (0.5 + β) & 1 1.00

τc = 0.25 √(fck) 1.37

KsTc(cl. 31.6.3 of IS 456:2000) 1.37

Compare Tv with KsTc (O.K) Tv<KsTc


N/mm2



mm2

mm2

mm2

mm2

How ever provide 10 mm bar @.. Bothways at top & bottom mats

mm2


N/mm2

N/mm2

N/mm2

Documents

Raft Design