Slab Bridge Final

ANALYSIS OF SIMPLY SUPPORTED SLAB BRIDGES -IRC :6-2010, IRC:21-2000 Recommended for spans less than 9 m ROHAN PERSAUD

1.0 INPUTS

BRIDGE ENGINEERING

Wearing course density: Clear span : Carriageway width Foothway with(each side): Slab thickness : Wearing course thickness: Width of bearing: Main bar dia.: Clear cover : Distribution bar dia.

3 25 kN/m 3 22 kN/m 6m 7.5 m 0.6 m 500 mm 75 mm 400 mm 20 mm 25 mm 12 mm

Effective depth (d): Effective Span (l):

465 mm 6.4 m

Concrete density:

Width of bridge :

Clause 112.1 of IRC:6 -minimum carrage way width

ERROR: IRC:21-Cla.304.3 : Min Clear Cover 40 mm

2.0 Dead loads Self wt. of slab: Self wt. of Wearing course: Total: 2.1 Max. Bending Moment: 2.2 Maximum Shear force :

8.7 m

2 12.5 kN/m 2 1.65 kN/m 2 14.15 kN/m

72.448 KNm. per m width of slab. 45.28 KN. per m width of slab.

ANALYSIS OF SIMPLY SUPPORTED SLAB BRIDGES -IRC :6-2010, IRC:21-2000

3.0 Live loads 3.1 Class AA Tracked Vehicle Table 2 of IRC:6 -for two lanes design purpose consider one lane of class AA vehicle. Impact factor :

19.75 %

Note: The track vehicle is places symmetrical of the span. Effective length of load: Effective Width of one track (be):

4.75 m 5.43 m

45o dispersion

Effective width of dispersion of both tracks, providing minimum clearance of 1.2 m and allowing for overlap of dispersion. Net effective width: 6.99 m 3.1.1 Intensity of loading : 3.1.2 Max. Bending Moment : Shear Force : New Effective Width of one track (be): New Net effective width:

2 25.25 KN/m

120.69 KNm. Per m width of slab. 5.13 m 6.84 m

New Intensity of loading :

2 25.79 KN/m

3.1.3 Max. Shear Force :

77.05 KN Per m width of slab.


3.2 Class AA wheeled Vehicle Table 2 of IRC:6 -for two lanes design purpose consider one lane of class AA vehicle. Impact factor : Width of dispersion parallel to span:

25 % 1.23 m

Effective length of load along the span :

2.43 m

Effective width of load perpendicular to span (be):

4.72 m

Dispersion areas overlap(45 degrees), and loads are placed symmetrical to the centre of span

Effective width of dispersion all wheels, providing minimum clearance of 1.2 m and allowing for overlap of dispersion. Net effective width: 6.51 m 3.2.1 Intensity of loading : 3.2.2 Max. Bending Moment : Shear Force : New Effective Width of one track (be): New Net effective width: New Intensity of loading : 3.2.3 Max. Shear Force :

2 31.60 KN/m 99.54 KNm. Per m width of slab.

3.17 m 5.37 m 2 38.29 KN/m 75.38 KN Per m width of slab.


3.3 Class A wheeled Vehicle Table 2 of IRC:6 -for two lanes design purpose consider two lane of class A vehicle. Impact factor : Width of dispersion parallel to span:

36.29 % 1.33 m

Dispersion areas overlap(45 degrees), and loads are placed symmetrical to the centre of span

Effective length of load along the span : 2.530 m Effective width of load perpendicular to span (be): 4.922 m Effective width of dispersion all wheels, providing minimum clearance of 1.2 m and allowing for overlap of dispersion. Net effective width: 8.76 m Limited effective width: 8.7 m 3.3.1 Intensity of loading : 3.3.2 Max. Bending Moment : Shear Force : New Effective Width of one track (be): New Net effective width: Limited effective width: New Intensity of loading : 3.2.3 Max. Shear Force :

2 14.12 KN/m 45.85 KNm. Per m width of slab.

6.423 m 9.51 m 8.7 m 2 5.56 KN/m 11.29 KN Per m width of slab.

Design Bending Moment :

120.69 KNm 72.448 KNm 193.14 KNm

Live load Dead load Per m width of slab.

Design shear force :

77.05 KN 45.28 KN 122.33 KN

live load Dead load Per m width of slab.

DESIGN OF SIMPLY SUPPORTED SLAB BRIDGES -IRC :6-2010,IRC:21-2000,IS:456-2010 Design Bending Moment : Design shear force :

193.14 KNm 122.33 KN

Per m width of slab. Per m width of slab.

1.0 INPUTS

Interpulate using table : 1.5 0.46

Concrete Grade : M Bar Grade : Fe

25 415

100As/bd:

0.52 1.75

x: 0.49

2.0 ALLOWABLE STRESS DESIGN : Premissable compressive stress of concrete (Qcb):

8.33 Mpa

Premissable tensile stress of rebars (Qst) : Modular ratio (m) : Neutral axis depth factor (n): Lever arm factor (j): Coefficient of Resistance (R):

200 Mpa 10 0.29 0.90 1.10

IRC-21: cl 304

2.1 Depth : Ultimate Moment (Mu) =Rbd2 Effective depth requited (dreq) = sqr.(Mu/b.R)

where b=1000 mm for slab

Effective Depth required (dreq) :

418 mm

Effective Depth provided (dprov) :

465 mm The Provided Depth of Slab is Sufficient

2.2 Main Tension Reinforcement : Area of tension rebars required (Asreq )= M/(Qst.j.dprov ) Asreq =

2 2302 mm per meter width of slab

Area of Tension Rerbars provided (Asprov) : Minimum Reinforcement (Asmin) :


Maximum Reinforcement (Asmax) : Asprov =

8

# bars at

2 2418 mm per meter width of slab 2 600 mm per meter width of slab

150

mm c/c

parallel to span

The Provided Area of Reinforcement is Sufficient

2 0.34 N/mm

2.3 Distribution Tension Reinforcement: Bending Moment Caused by Lateral Distribution of load (Mlat) = 0.3 Mlive + 0.2 Mdead Mlat :

50.7 KNm

Effective depth to distribution dar (d1) : Area of tension rebars required (Asreq )= Mlat/(Qst.j.d1 ) Asreq =

IRC-21: cl 305-18

Per m width

449 mm


Area of Tension Rerbars provided (Asprov) : Minimum Reinforcement (Asmin) : Maximum Reinforcement (Asmax) : Asprov =

8 # bars at

2 904 mm per meter width of slab 2 600 mm per meter width of slab 2 20000 mm per meter width of slab

150 mm c/c perpendicular to main bars IRC:21-Cla.303.4: Spacing -150mm for crack control The Provided Area of Reinforcement is Sufficient

2.4 Strinkage and Temperature Reinforcement at top of slab : Maximum spacing of bars : Minimum steel area : Asprov =

5

# bars at

300 mm IRC:21-Cla. 305.10 2 250 mm per meter width of slab 250 mm c/c Both ways The Provided Area of Reinforcement and Spacings are Sufficient

2.5 Shear Check Maximum Shear Force : Design Shear Stress :

122.33 KN 2 0.26 N/mm

2 Max. Permissable Shear Stress : 1.9 N/mm Permissible Shear Stress: (100.Asprov)/(b.d) : 0.52 By Interpulation using above table 2 Permissable Shear stress in concrete (Tc) : 0.34 N/mm The Section is Adequte for Shear Resistance

Slab Bridge Final

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