Corbel Raina

General Details of Bracket / Corbel

STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Intro

Date:

Job:

Note No:

ISBT Flyover on NH37

Bracket for Future Prestressing Height of Lighting Post (Approximate Height) Thickness Sectional Area of the Lighting Post

= = =

11.50 m 0.006 m 0.01 m^2

Total Volume

=

0.0575 m^3

Density of Material

=

Weight of Lighting Post = Increasing by 10% to cater for the services and other joinings Weight of Lighting Post = say = =

7850 kg/m^3 451.4 kg 496.5 kg 500 kg 5 kN

1/14/2015

Debabrata 1/14/2015

STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Corbel

Date:

Job:

Note No:

ISBT Flyover on NH37

1/14/2015

Bracket for Future Prestressing The following calculations are carried out following the design procedures of " Concrete Bridge Practice : Analysis, Design and Economics " by Dr. V.K.Raina. ) Basic Inputs 1. Distance of point load from face of support a = 1264 mm 2. Overall depth of section at face of support h = 3300 mm 3. Clear Cover c = 40 mm 4. Dia of main reinforcement = 25 mm  5. Effective Depth of Section (with double layer reinf.) d' = 3222.5 mm 6. Design Depth of Section ( d = 0.8 d' ) d = 2578 mm 7. Depth of section at edge s = 1850 mm 8. Width of Cantilever / Corbel / Bracket b = 1200 mm 9. Grade of Concrete = 40 fsy 10. Grade of Reinforcement = 415 Mpa Vu 11. Ultimate Shear Value = 2850 kN Hu 12. Actual Horizontal Load = 0 kN Conditions Condition I For the section to be designed as a corbel " a / d' " shall be less than 1. Hence a / d' = 1264 / 3222.5 = 0.392 < 1.0 As the ratio " a / d' " is less than 1 so the section is to be designed as a corbel Condition II For the section to be designed as a corbel " s / d' " shall be greater than 0.5. Hence s / d' = 1850 / 3222 = 0.57 > 0.5 Proceed with the design Loadings Vertical Load (Vu) Ultimate Shear Value

2850.00

kN

(Refer to separate calculations)

Horizontal Load (Hu) Hu = 1.7 x actual horizontal force in working load condition but not less than 0.2 * V u = = 0.2 x 2850 Maximum Horizontal Load " H u " 570.00 kN

=

0

kN

=

570.00

kN

Now the design for the corbel is carried out as per the following steps. STEP I Check for Nominal Shear Strength Ensure V u / b d < = 0.15 fc' Vu where; = 2850.00 kN = = = = = = = = =

bd Therefore; V V Now;

/bd /bd u fc' u

0.15 fc'

Hence V

u

2850000 N 1200 x 2578 sqmm 3093600 mm2 2850000 / 3093600 0.92 N / mm2 28 - day standard cylinder strength of concrete used. 0.80 times the standard cube strength 0.15 x 0.8 x 40 4.80 N / mm2 Ensured

/ b d < = 0.15 fc' is

Ensured

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STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Corbel

Date:

Job:

Note No:

ISBT Flyover on NH37

1/14/2015

STEP II Calculation of Shear Friction Reinforcement " A

where;

A vf

=

fsy

=

V

vf

"

u

0.85 fsy  yeild stress value of the reinforcement used.

=

415

N/ mm2



Type of Surface 1

Concrete placed monolithically across interface.

1.40

2

Concrete placed against hardened concrete but with roughened surface

1.00

3

Concrete anchored to structural steel

0.70

4

Concrete placed against hardened concrete but surface not roughened

0.60

Type of Surface (1/2/3 /4)

2

= 1  (for Concrete placed against hardened concrete but with roughened surface) 2850 x 1000 A vf = mm2 0.85 x 415 x 1 A vf = 8079 mm2 STEP III Calculation for Direct Tension Reinforcement " A t ". At

=

Hu

=

At

= =

Hu 0.85 fsy 570.00

kN

570 x 1000 0.85 x 415 1616

mm2 mm2

STEP IV Calculation for Flexural Tension Reinforcement " A f " Af

= = =

[V

u

a+H

u

( h - d' ) ]

0.85 fsy d [ ( 2850 x 1000 x 1264 ) + ( 570 x 1000 ) x ( 3300 - 3222.5 ) ] 0.85 x 415 x 2578 4010 mm2

STEP V Total Primary Tensile Reinforcement " A A

s

s

"

>=

(Af+At)

>=

(2/3A

>=

Provide the largest of these three magnitudes as Total Primary ( 0.04 fc' / fsy ) b d' Tensile Reinforcement As. vf

+At)

(Af+At)

=

4009.92 + 1615.88

(2/3A

= =

5625.79 2 / 3 x 8079.38 + 1615.88

= =

7002.13

=

11927.13

=

maximum of ( 5625.79 , 7002.13 , 11927.13 )

vf

+At)

( 0.04 fc' / fsy ) b d' Hence

A

s

mm2 mm2 mm2

mm2 0.04 x 0.8 x 40 / 415 x 1200 x 3222. mm2 mm2

Page-

STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Corbel

Date:

Job:

Note No:

ISBT Flyover on NH37

=

11927

1/14/2015

mm2

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STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Corbel

Date:

Job:

Note No:

ISBT Flyover on NH37

STEP VI The total sectional area of the stirrups is " A

h

1/14/2015

" (closed ties) to be provided horizontally, one below

the other, and next to " As " A Therefore; 0.5 * A f

=

0.5 x 4009.92

=

2004.96 mm A Hence;

h

>=

0.5 * A

>=

0.333 * A

and

0.333*A

Provide the largest of these two magnitudes as Ah.

f vf

vf

2

= =

h

STEP VII The total steel in vertical stirrups is " A A

v

v

A

v

s

Diameter of Primary Steel Area of one bar No. of Bars provided A s provided

=

###

=

0.50 * ( V

in kgs = = =

= = = = =

u

sy

-Vc)*p d

= 10 x 120 x 257.8 = 309360 kg = 3093.6 kN 225 mm 0.5 x ( 2850 - 3093.6 ) x 225 x 1000 415 x 2578 -25.62 Though no steel is rerquire we provide mm2 some R/F for extra R/F s

"

11927 mm2 25 mm 490.87 mm2 26 nos. 26 * 490.88

= 12763 mm2 > So we provide 26 nos. 25 mm diameter bars as main reinforcement Horizontal Steel ( Closed Stirrups) " A h " A

mm2

"

Reinforcement Details Total Primary Tensile Reinforcement " A A

0.333 x 8079.38

maximum of ( 2004.96 , 2690.43 ) 2690 mm2

f Now; Vc = 10 bd where b & d are in cms Pitch Av

=

A

s

R/F is adequate

= 2690.43 mm2 The stirrups shall be provided below As and within a depth of " 2 / 3 d' " below As. h

2 / 3 d' Diameter of Stirrup Bar Area of one bar No. of layers of Stirrups Spacing of Stirrups No. of legs of stirrups A h provided

= = = = = = = =

(2 / 3 ) x 3222.5 2149.00 mm 10 mm 78.54 mm2 5 nos. 430 mm 8 78.54 x 5 x 8

Ah = 3142 mm2 > R/F is adequate So we provide 8 legged 10 mm diameter bars as horizontal stirrups in 5 layers Vertical Steel ( Closed Stirrups) " A v " A

v

Diameter of Stirrup Bar Area of one bar Pitch No. of legs of stirrups A v provided

= = = = = = =

-25.62 10 78.54 225 4 78.54 x 4

mm2 mm mm2 mm

314.16 mm2

>

A

v

R/F is adequate

Page-

STUP Consultants P Ltd.

Designed ByDebabrata

'file:///var/www/apps/conversion/tmp/scratch_6/257217810.xls'#$Corbel

Date:

Job:

Note No:

ISBT Flyover on NH37

1/14/2015

So we provide 4 legged 10 mm diameter bars as vertical stirrups at 225 mm spacing

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Proceed with the design

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Though no steel is rerquire we provide

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