t girder bridge deck diaphragm-20 m

7/23/2019 T Girder Bridge Deck Diaphragm-20 m

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Page 17

DESIGN OF DECK-SLAB

1.0 INTRODUCTION :

The deck-slab is designed as continuous over three supports with overhang on either side.

Live-load combinations of Class-A X 2 Lane loading ,Axle Load have been checked. BendingMoments at various sections as shown below are found using STAAD-Pro software after calculating

effective load intensities for each case.

2.0 DESIGN DATA:

I Density of concrete = 2.40 t/m3

ii Grade of concrete = M- 25

iii Reinforcement = HYSD bars conforming to IS: 1786

iv Permissible stress in concrete = 8.33 N/mm2

v Permissible stress in steel = 200 N/mm2

vi Maximum permissible shear stres = 2.10 N/mm2

vii Live Load

a) Class A x 2 Lanes

viii Impact Factor

= 50.0% For Class-A

3.0 REFERENCES:

i. IRC: 6 - 2000

ii. IRC: 21 - 2000

550 (other side)

550 C/L Carriageway

1 2 3

300

200 235

50

1 2 150

3

325 325

1500 1800 1800


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Page 18

4.0 LOAD CALCULATION

a) Dead Load:

(loads are calculated for one meter strip)

In cantilever portion,

Load is linearly varying in cantilever portion

At end = 0.48 t/m

At 1-1 = 0.6 t/m

In intermediate portion,

Uniformly applied load = 0.564 t/m

b) SIDL :

Outer side,

S/W of Parapet/Side rail = 0.3 t/m

Due to road kerb = 0.396 t/m

U.D.L due to wearing coat = 0.075 x 2.4 = 0.180 t/m

0.3 0.3

0.15 0.15

0.396 0.18 0.396

0.55 0.55


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Page 19

c) Live load:

Transverse Positions for various Live load cases have been shown in proceeding

sheets.Effective load intensities are calculated & used in STAADPro 2007 as input to

analyse the deck-slab for various load cases.

4.0 CALCULATION OF EFFECTIVE LOAD INTENSITY

THICKNESS OF THE WEARING COAT = 0.075 m

DEPTH OF SLAB = 0.235 m

WIDTH OF SLAB ( c/c of diaphragm) b = 18.460 m

EFFECTIVE LENGTH lo = 1.80 m

VALUE OF a = 2.6

CONTACT AREA:

CLASS A 1 500 250 (FOR LOAD 11.4 t)

WIDTH FOR OVERLAP 1.20 m

CLASS 70 R (Max. Axle Load) 2 360 260 (FOR LOAD 20 t)


CLASS 70 R (T) 3 840 4570 (FOR LOAD 70 t)

CLASS 70 R (Max. Axle Load) 4 360 260 (FOR LOAD 20 t)


IMPACT FACTOR (%) :

CLASS A 50

1.80 1.80

0.550 0.95 3.6 0.95 0.55

6.60


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Page 20

LOAD CASE 1 Most Eccentric position for Class A x 2 lanes

LOAD

WITH

IMPACT

a

DISP.

ALONG

SPAN

beff. bOVER-

LAPPIN

G

EFF.

LOAD

INT.

P1 5.70 8.55 1 500 250 0.550 1.12 1.060 1.2 NO 8.066P2 5.70 8.55 1 500 250 0.550 1.12 1.393 1.2 YES 6.595

P3 5.70 8.55 1 500 250 0.550 1.12 1.393 1.2 YES 6.595

P4 5.70 8.55 1 500 250 0.550 1.12 1.393 1.2 YES 6.595

# indicates load is in cantilever portion

LOAD CASE 2 Class A single lane Eccentrically placed

LOAD

WITH

IMPACT

a

DISP.

ALONG

SPAN

beff. bOVER-

LAPPIN

G

EFF.

LOAD

INT.

P1#

5.70 8.55 1 500 250 0.550 1.12 1.060 1.2 NO 8.066

P2 5.70 8.55 1 500 250 0.550 1.12 1.393 1.2 YES 6.595

LOAD CASE 3 One Wheel of Class A single lane placed Centrally on span

LOAD

WITH

IMPACT

a

DISP.

ALONG

SPAN

beff. bOVER-

LAPPIN

G

EFF.

LOAD

INT.

P1 5.70 8.55 1 500 250 0.900 1.12 1.570 1.2 YES 6.173

P2 5.70 8.55 1 500 250 0.900 1.12 1.570 1.2 YES 6.173

CONTACT AREALOAD

LOAD CONTACT AREA

LOAD CONTACT AREA


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I NPUT FI LE: STUP27M. STD

1. STAAD PLANE 20M DECK SLAB ANALYSI S OVER 3 GI RDERS

2. I NPUT WI DTH 72

3. UNI T METER MTON

4. J OI NT COORDI NATES

5. 1 . 000 . 000 . 000

6. 2 1. 500 . 000 . 000 7. 3 3. 200 . 000 . 000

8. 4 5. 100 . 000 . 000

9. 5 6. 600 . 000 . 000

10. MEMBER I NCI DENCES

11. 1 1 2

12. 2 2 3

13. 3 3 4

14. 4 4 5

15. MEMBER PROPERTY I NDI AN

16. 1 TO 4 PRI YD . 2 ZD 1.

17. CONSTANT

18. E CONCRETE ALL 19. DENSI TY CONCRETE ALL

20. SUPPORT

21. 2 TO 4 PI NNED

22. LOAD 1 DEAD LOAD

23. SELFWEI GHT Y - 1.

24. MEMBER LOAD

25. *WEARI NG COURSE

26. 1 UNI GY - . 18 . 55 1. 5

27. 4 UNI GY - . 18 0. . 95

28. 2 3 UNI GY - . 12

29. *HANDRAI L

30. 1 CON GY - . 3 . 15

31. 4 CON GY - . 3 1. 25

32. * ROAD KERB

33. 1 UNI GY - . 3 0. . 55

34. 4 UNI GY - . 3 . 95 1. 5

35. LOAD 2 LI VE LOAD ( MOST ECCY. POSI TI ON - 2 LANES)

36. MEMBER LOAD

37. 1 CON GY - 8. 366 . 85

38. 2 TO 4 CON GY - 6. 663 . 55

39. LOAD 3 LI VE LOAD ( MOST ECCY. POSI TI ON - 1 LANE)

40. MEMBER LOAD

41. 1 CON GY - 8. 366 . 85

42. 2 CON GY - 6. 663 . 55

43. LOAD 4 LI VE LOAD ( CENTRALLY PLACED - 1 LANE) 44. MEMBER LOAD

45. 1 CON GY - 6. 259 . 9

46. 2 TO 4 CON GY - 6. 259 . 9

47. PERFORM ANALYSI S


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48. PRI NT SUPPORT REACTI ONS

SUPPORT REACTI ON

SUPPORT REACTI ONS - UNI T MTON METE STRUCTURE TYPE = PLANE

J OI NT LOAD FORCE- X FORCE- Y FORCE- Z MOM- X MOM- Y MOM Z

2 1 0. 00 2. 50 0. 00 0. 00 0. 00 0. 00

2 0. 00 15. 62 0. 00 0. 00 0. 00 0. 00

3 0. 00 15. 72 0. 00 0. 00 0. 00 0. 00 4 0. 00 11. 15 0. 00 0. 00 0. 00 0. 00

3 1 0. 00 - 0. 36 0. 00 0. 00 0. 00 0. 00

2 0. 00 1. 94 0. 00 0. 00 0. 00 0. 00

3 0. 00 - 0. 86 0. 00 0. 00 0. 00 0. 00

4 0. 00 1. 35 0. 00 0. 00 0. 00 0. 00

4 1 0. 00 2. 43 0. 00 0. 00 0. 00 0. 00

2 0. 00 10. 80 0. 00 0. 00 0. 00 0. 00

3 0. 00 0. 17 0. 00 0. 00 0. 00 0. 00

4 0. 00 12. 54 0. 00 0. 00 0. 00 0. 00

**** **** **** ** END OF LATEST ANALYSI S RESULT ** **** ** **** **

49. PRI NT MEMBER FORCES ALL MEMBER FORCES ALL

MEMBER END FORCES STRUCTURE TYPE = PLANE ALL UNI TS ARE - - MTON METE

MEMBER LOAD J T AXI AL SHEAR- Y SHEAR- Z TORSI ON MOM- Y MOM- Z

1 1 1 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

2 0. 00 1. 22 0. 00 0. 00 0. 00 - 1. 06

2 1 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

2 0. 00 8. 37 0. 00 0. 00 0. 00 - 4. 60

3 1 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

2 0. 00 8. 37 0. 00 0. 00 0. 00 - 4. 60

4 1 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

2 0. 00 6. 26 0. 00 0. 00 0. 00 - 3. 13

2 1 2 0. 00 1. 28 0. 00 0. 00 0. 00 1. 06

3 0. 00 - 0. 19 0. 00 0. 00 0. 00 0. 26

2 2 0. 00 7. 25 0. 00 0. 00 0. 00 4. 60

3 0. 00 - 0. 59 0. 00 0. 00 0. 00 0. 12

3 2 0. 00 7. 35 0. 00 0. 00 0. 00 4. 60

3 0. 00 - 0. 69 0. 00 0. 00 0. 00 0. 30

4 2 0. 00 4. 89 0. 00 0. 00 0. 00 3. 13

3 0. 00 1. 37 0. 00 0. 00 0. 00 0. 04

3 1 3 0. 00 - 0. 17 0. 00 0. 00 0. 00 - 0. 26 4 0. 00 1. 25 0. 00 0. 00 0. 00 - 1. 01

2 3 0. 00 2. 52 0. 00 0. 00 0. 00 - 0. 12

4 0. 00 4. 14 0. 00 0. 00 0. 00 - 3. 66

3 3 0. 00 - 0. 17 0. 00 0. 00 0. 00 - 0. 30

4 0. 00 0. 17 0. 00 0. 00 0. 00 0. 00

4 3 0. 00 - 0. 02 0. 00 0. 00 0. 00 - 0. 04

4 0. 00 6. 28 0. 00 0. 00 0. 00 - 5. 63


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4 1 4 0. 00 1. 18 0. 00 0. 00 0. 00 1. 01

5 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

2 4 0. 00 6. 66 0. 00 0. 00 0. 00 3. 66

5 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

3 4 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

5 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00

4 4 0. 00 6. 26 0. 00 0. 00 0. 00 5. 63 5 0. 00 0. 00 0. 00 0. 00 0. 00 0. 00


50. SECTI ON 0. 88 MEMBER 1

51. PRI NT MEMBER SECTI ON FORCES LI ST 1

MEMBER SECTI ON FORCES LI ST

MEMBER FORCES AT I NTERMEDI ATE SECTI ONS ALL UNI TS ARE - - MTON METE

MEMB LOAD SEC SHEAR- Y SHEAR- Z MOM- Y MOM- Z

1 1 0. 88 - 1. 12 0. 00 0. 00 0. 86

2 0. 88 - 8. 37 0. 00 0. 00 3. 20 3 0. 88 - 8. 37 0. 00 0. 00 3. 20

4 0. 88 - 6. 26 0. 00 0. 00 2. 08


52. SECTI ON 0. 09 0. 5 0. 91 MEMBER 2 3

53. PRI NT MEMBER SECTI ON FORCES LI ST 2 3

MEMBER SECTI ON FORCES LI ST

MEMBER FORCES AT I NTERMEDI ATE SECTI ONS ALL UNI TS ARE - - MTON METE

MEMB LOAD SEC SHEAR- Y SHEAR- Z MOM- Y MOM- Z

2 1 0. 09 1. 18 0. 00 0. 00 0. 86

0. 50 0. 73 0. 00 0. 00 0. 15

0. 91 0. 29 0. 00 0. 00 - 0. 22

2 0. 09 7. 25 0. 00 0. 00 3. 43

0. 50 0. 59 0. 00 0. 00 0. 41

0. 91 0. 59 0. 00 0. 00 - 0. 03

3 0. 09 7. 35 0. 00 0. 00 3. 41

0. 50 0. 69 0. 00 0. 00 0. 32

0. 91 0. 69 0. 00 0. 00 - 0. 19

4 0. 09 4. 89 0. 00 0. 00 2. 34 0. 50 4. 89 0. 00 0. 00 - 1. 27

0. 91 - 1. 37 0. 00 0. 00 - 0. 26

3 1 0. 09 - 0. 27 0. 00 0. 00 - 0. 23

0. 50 - 0. 71 0. 00 0. 00 0. 13

0. 91 - 1. 15 0. 00 0. 00 0. 82

2 0. 09 2. 52 0. 00 0. 00 - 0. 53

0. 50 - 4. 14 0. 00 0. 00 - 0. 06


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0. 91 - 4. 14 0. 00 0. 00 2. 99

3 0. 09 - 0. 17 0. 00 0. 00 - 0. 27

0. 50 - 0. 17 0. 00 0. 00 - 0. 15

0. 91 - 0. 17 0. 00 0. 00 - 0. 03

4 0. 09 - 0. 02 0. 00 0. 00 - 0. 04

0. 50 - 0. 02 0. 00 0. 00 - 0. 02

0. 91 - 6. 28 0. 00 0. 00 4. 62 **** **** **** ** END OF LATEST ANALYSI S RESULT ** **** ** **** **

54. FI NI SH


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Page 22

7.0 SUMMARY OF DESIGN MOMENTS

SECT.

HOGGING SAGGING HOGGING SAGGING

1-1 3.20 0.00 0.86

2-2 0.41 1.27 0.15 0.00

3-3 2.99 1.93 0.82 0.23

For Cantilever portion

Dead Load Moment at section 1-1 0.86 tm

Live-Load Moment 3.20 tm

8.0 DESIGN OF REINFORCEMENT

DIA. OF MAIN REINF. 12 mm

DIA. OF DISTRIBUTION REINF. 10 mm

DEPTH OF SLAB - AT INTERM. SECTION. 235 mm

DEPTH OF SLAB - AT CANTIL.SECTION. 250 mmCLEAR COVER TO REINFORCEMENT 40 mm

EFF. DEPTH FOR MAIN STEEL - AT INTERM. SECTION. 189 mm

EFF. DEPTH FOR MAIN STEEL - AT CANTIL. SECTION. 204 mm

EFF. DEPTH FOR DISTRIB. STEEL - AT INTERM. SECTION. 178 mm

EFF. DEPTH FOR DISTRIB. STEEL - AT CANTIL. SECTION. 183 mm

MIN. REINFORCEMENT 2.82 cm2

GRADE OF CONCRETE M- 25 N/mm2

PERM. BENDING COMP. STRESS 8.33 N/mm2

CONSTANT j , 0.902

CONSTANT Q , 110 t/m2

SECT.

HOGGING SAGGING

AT

TOP

AT

BOTTOM HOGGING SAGGING

AT

TOP

AT

BOTTOM

1-1 4.06 0.00 10.82 0.00 1.13 0.00 3.36 0.00

2-2 0.56 1.27 1.61 3.65 0.15 0.38 0.47 1.16

3-3 3.81 2.16 10.96 6.21 1.06 0.63 3.24 1.91

DEPTH REQUIRED AT SECTION 1-1 = 191.7 mm < Provided ,Hence O.K.

DEPTH REQUIRED AT

INTERMEDIATE-SECTIONS = 185.7 mm < Provided ,Hence O.K.

SECT.

1-1

2-2

3-3

AT BOTTOM

LIVE LOAD MOMENTS

DEAD LOAD MOMENTS

& SIDL MOMENTS

DESIGN MOMENTS MAIN STEEL

DISTRIB. STEEL PROVIDED

DISTRIBUTION STEELDISTRIB. MOMENTS

12#@ 200 +

12#@200C/C

12 # @ 150 C/C 10# @ 200 C/C12#@ 200 +

12#@200C/C

12 # @ 150 C/C

AT TOPAT TOPMAIN STEEL PROVIDED

AT BOTTOM

8# @ 200 C/C

10# @ 200 C/C

8# @ 200 C/C

12#@ 200 +

12#@200C/C8# @ 200 C/C 10# @ 200 C/C

8# @ 200 C/C


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9.0 DESIGN OF DIAPHRAGM :

9.1 Design of End Diaphragm :

Dead Load Analysis : 0.28

Load from the hatched area will constitute

the local effect.

1.8 m 1.8 m

Self weight of Diaphragm = 2.45 t

Deck slab & Wearing coat = ( 5.5 x 0.28 + 1/2 x 1.8 x 0.9 x 2 ) x 0.234 x 2.4

= 1.32 t

Wearing coat = ( 5.5 x 0.28 + 1/2 x 1.8 x 0.9 x 2 ) x 0.075 x 2.2 = 0.42 t

Total load = 6.21+ 1.49 + 0.29 = 4.19 t

This load is assumed as a uniform load over a length of 5.0m

U.D.L = 4.19 / 3.6 = 1.16 t/m

Load outside deck slab etc. outside the hatched area will be carried by the main girder

and transmitted directly to the bearings without causing any bending moment and

shear forces in the diaphragm.

Total D L effect is as below1.16 t/m

A B C

1.8 m 1.8 m

Maximum + Ve moment = 0.07 x 1.84 x 1.8 = 0.26 tm

Maximum - Ve moment = 0.125 x 1.84 x 1.8 = 0.47 tm

Maximum shear force = 0.55 x 1.84 x 1.8 = 1.15 t


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Live Load Analysis :

Parts of live load in 45oinflunce area will only go to the diaphrm. Parts outside this area will go

directly to the main girder and will not cause any B.M and S.F in the diaphragm. Class A x 2 lanes

will cause max. effect.

Case I : Placing One track in the mid span TR - I TR - I

0.90 m 0.90 mbeff for 5.7t load along traffic dirn

= 0.82 m

A 1.8 m B 1.8 m C

Load from each Track = 1.5 x 5.7

= 8.55 t

0.82

1.18

0.5

Reaction at A RA = 8.55 x (0.406 - 0.094 ) = 2.67 t

[Coefficients are takenfrom " STEEL DESIGNERS

MANUAL"]

Max. span moment = 2.67 x 0.9

= 2.40 tm

Max. support moment = 2.67 x 1.8 - 8.55 x 0.9 = -2.89 tm

Shear force at B = 2.67 - 8.55 = -5.88 t

Summary of Design moment and shear force :

Moment at support = 3.36 tm

Moment at mid span = 2.66 tm

Maximum shear force = 7.04 t

Overall depth available near outer girder location = 1.6 - 0.1 = 1.5 m

Effective depth = 1500 - 50 - 12 - 10 = 1428 mm = 1.428 m

Width of beam = 325 mm = 0.325 m

Moment of resistance = 110 x 0.325 x 1.8282 = 51.05 tm >> 3.36 tm

Area of steel required = 3.79 / ( 2 x 0.902 x 1.828 ) 1.31 sq.cm

But minimum steel = 0.2 x 32.5 x 142.8 x 10-2

= 9.282 Sq.cm

Provide 5 nos 20 # bars both at top and bottom.

Provide 2 L 10 # stirrups @ 200 c/c all through


12/14

Jacking condition.

Reaction at end bearing due to dead load and SIDL = 31.92 t

Reaction at inner bearing due to dead load and SIDL = 31.92 t

End cross girder will be designed for jack lifting . BM & SF Ref. STAAD Output Jack lifting file

1. STAAD PLANE J ACK LI FTI NG ANALYSI S OF GI RDERSI NPUT FI LE: 20 M _Di aphr agm. STD

2. START J OB I NFORMATI ON

3. ENGI NEER DATE 01- SEP- 12

4. END J OB I NFORMATI ON

5. I NPUT WI DTH 79

6. UNI T METER MTON

7. J OI NT COORDI NATES

8. 1 0 0 0; 2 0. 6 0 0; 3 1. 2 0 0; 4 1. 8 0 0; 5 2. 4 0 0; 6 3 0 0;

7 3. 6 0 0

9. MEMBER I NCI DENCES

10. 1 1 2; 2 2 3; 3 3 4; 4 4 5; 5 5 6; 6 6 7

11. DEFI NE MATERI AL START

12. I SOTROPI C CONCRETE 13. E 2. 17185E+007

14. POI SSON 0. 17

15. DENSI TY 23. 5616

16. ALPHA 1E- 005

17. DAMP 0. 05

18. END DEFI NE MATERI AL

19. CONSTANTS

20. MATERI AL CONCRETE ALL

21. MEMBER PROPERTY I NDI AN

22. 1 TO 6 PRI S YD 1. 965 ZD 0. 325

23. SUPPORTS

24. 2 3 5 6 PI NNED

25. LOAD 1 DEAD LOAD 26. SELFWEI GHT Y - 1

27. J OI NT LOAD

28. 1 FY - 31. 923

29. 4 FY - 31. 923

30. 7 FY - 31. 923

31. PERFORM ANALYSI S

32. PRI NT SUPPORT REACTI ON

J ACK LI FTI NG ANALYSI S OF GI RDERS

SUPPORT REACTI ONS - UNI T MTON METE STRUCTURE TYPE = PLANE

- - - - - - - - - - - - - - - - -

J OI NT LOAD FORCE- X FORCE- Y FORCE- Z MOM- X MOM- Y MOM Z

2 1 0 58. 09 0 0 0 03 1 0 8. 61 0 0 0 0

5 1 0 8. 61 0 0 0 0

6 1 0 58. 09 0 0 0 0

** ** ** ** ** ** ** END OF LATEST ANALYSI S RESULT **** ** ** ** ** **

33. PRI NT MEMBER FORCES ALL


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J ACK LI FTI NG ANALYSI S OF GI RDERS

MEMBER END FORCES STRUCTURE TYPE = PLANE

- - - - - - - - - - - - - - - - -

ALL UNI TS ARE - - MTON METE ( LOCAL )

MEMBER LOAD J T AXI AL SHEAR- Y SHEAR- Z TORSI ON MOM- Y MOM- Z1 1 1 0 - 31. 92 0 0 0 0

2 0 38. 19 0 0 0 - 21. 04

2 1 2 0 19. 90 0 0 0 21. 04

3 0 - 13. 63 0 0 0 - 10. 98

3 1 3 0 22. 23 0 0 0 10. 98

4 0 - 15. 96 0 0 0 0. 48

4 1 4 0 - 15. 96 0 0 0 - 0. 48

5 0 22. 23 0 0 0 - 10. 98

5 1 5 0 - 13. 63 0 0 0 10. 986 0 19. 90 0 0 0 - 21. 04

6 1 6 0 38. 19 0 0 0 21. 04

7 0 - 31. 92 0 0 0 0

** ** ** ** ** ** ** END OF LATEST ANALYSI S RESULT **** ** ** ** ** **

34. FI NI SH

Max. hogging moment at support = 21.04 t-m

Max. sagging moment at span = 0.5 t-m

38.2 t

Cross girder will be designed as continuous rectanguler deep beam

Effetive span ( l ) = 1.32 m

1.60 m

l / D = 0.83 < 1

Lever arm z = 0.66

Bottom reinforcement = 0.26 cmMinimum Reinforcement required is , 9.28 cm

Providing 10 No. dia 16 # in five layers.

Ast provided = 20.11 cm

Top reinforcement = 11.14 cm

Providing 10 No. dia 16 # in five layers.

Over all depth ( D ) =

As per Cl. 29.2 IS 456 -2000

Max. shear force =


14/14

Ast provided = 20.11 cm

Reinforcement shall be provided as per Cl 29.2 IS:456-2000 and is shown in drawing.

For Shear

Providing 2 Legged # 16 stirrups

Asw = 59.93 x 10000 = 6.69 cm/m

s 200 x 202.8 x 2.0

Providing 2 -Legged 16 # stirrups @150 c/c

9.2 Design of Intermediate Diaphragm :

Self weight of Diaphragm = 2.43 t

Self weight of Deck Slab and Wearing coat

= 2 x 1/2 x 1.8 x 0.9 x 2 x 0.234 x 2.4 1.82 t

1.8 1.8

U.D.L = ( 2.43 + 1.82 ) / 3.6 = 1.18 t/m

The support of the intermediate diaphragm will act as a spring , hence reaction = (2.43 + 1.82 ) / 3

= 1.42 t

1.18 t/m

Dead load bending moment At A = 0

A B C

At B =1.18x0.9-1.42x0.9/2 = 0.80 tm 1.8 m 1.8 m

At C = 1.18x1.8-1.62x1.8/2 = 0.64 tm

Dead load shear force

At A = 1.42 t

At B = 0.35 t

At C = -0.71 t

Live Load :

Parts of live load in 45oinflunce area will only go to the diaphrm. Parts outside this area will go

directly to the main girder and will not cause any B.M and S.F in the diaphragm.

Live load on diaphragm from each track = 1.5 x 5.7 = 8.6 t

Reaction = 2 x8.6 /3 = 5.7 t

Maximum L.L moment = 5.7 x 1.8 - 8.6 x 0.9 = 2.6 tm

Design moment = 3.20 tm

deff.

= 1950-62-10 =1878 mm = 1.878 m

Width = 325 mm = 0.325 m

Area of steel required = 3.20 / ( 2 x 0.902 x 1.478 ) = 0.95 Sqcm

Provide 4 nos 20 # bars both at top and bottom.

Provide 2 L 10 # stirrups @ 200 c/c all through

t girder bridge deck diaphragm-20 m

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