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Superpassage Design Specifications

This document provides design details for a superpassage with a clear span of 5m and discharge of 32 lps. It calculates loads, bending moments, shear forces, and steel reinforcement requirements for the slab and side beams. The slab thickness is designed as 200mm with 10mm bars at 100mm c/c on top and bottom. The side beam depth is 554mm with 6 bars of 20mm diameter and 10mm distribution bars at 90mm c/c. Shear reinforcement of 8mm stirrups at 200mm c/c is also specified for the beam.

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Samir Rawat
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833 views5 pages

Superpassage Design Specifications

This document provides design details for a superpassage with a clear span of 5m and discharge of 32 lps. It calculates loads, bending moments, shear forces, and steel reinforcement requirements for the slab and side beams. The slab thickness is designed as 200mm with 10mm bars at 100mm c/c on top and bottom. The side beam depth is 554mm with 6 bars of 20mm diameter and 10mm distribution bars at 90mm c/c. Shear reinforcement of 8mm stirrups at 200mm c/c is also specified for the beam.

Uploaded by

Samir Rawat
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as XLSX, PDF, TXT or read online on Scribd
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Design of Superpassage

Clear span (L) = 5m


Discharge(Q) = 32 lps
Assumed slope of flume(s) = 0.002

Assumptions
Super passage trough will have the same section as that of line canal u/s and d/s
Width of the trough(B) = 0.50 m
Depth of the water(d)= 0.15 m
Free board (FB) = 0.20 m

Density of concrete(d) = 25 kN/m3


Assume M15 grade of concrete and tor steel are used.
Tensile strength of steel(pst) = 230 N/mm2
Compression in bending of concrete(pbc) = 5 N/mm2

Design of slab
For design, 1m width of slab is taken
Assume slab thickness = 0.20 m
Slab dead wt, 0.20*25 = 5.00 KN/m
Loads on slab due to water 3.54 KN/m
Total imposed load(W) = 8.54 KN/m

Effectice span = L+0.30/2 = 0.65 m

Maximum bending moment = WxLe2/8 0.45 KNm

Maximum Shear force = WxLe/2 2.7755 KN

Slab thickness
M = R bd2
Where R= 0.65 for M15 concrete and tor steel

d = (M/Rb)2 65.345237 mm
Assume cover to reinforcement 40 mm
Slab total depth = d+cover+5 110.34524 mm

Assumed slab thickness = 200 mm OK

Therefore slab effective thickness(d) = 155 mm

Steel required
Ast = M/pstxjxd
j is lever arm = 0.904 for M15 concrete and tor steel

Ast = 13.994798 mm2

Minimum amount of steel required 0.25% of Ac


= 500 mm2

Provide 10mm @ 157 mm c/c but greater than slab effective thickness
Hence provide 10 mm bar @ 100 mm c/c
As there is negative moment at the support of slab, provide the same at top of the slab also.
Distribution steel 0.15% of Ac 300 mm2

Provide 10 mm bars 262 mm c/c


adopt = 150 mm c/c

Check shear stress

qv = SF/bd = 0.0179065 N/mm2


This is well below the permissible shear stress
Hence no need of shear reinforcement required.
Side beam design

Depth of beam = 1/10 of clear span 0.5 m


But overall depth D = 0.55 m

Width of beam 1/2 of D 0.25 m


But width of beam W = 0.30 m

Loads on beam KN/m


Beam dead wt. 0.3x0.52x25 4.155
Walkway slab 1/2x0.15x0.70x25 1.75
Live load 1/2x2.5KN/m2 2.5
Base slab 1/2x0.15x0.33x25 0.83
Water load 1/2x0.33x0.37*10 0.885
Total 10.12

Assume support width 0.40m


Effective span 0.4+clear span 5.4 m

Maximum bending moment


WxLe2/8 36.869175 KN-m

Maximum Shear force(assumed at support)


WxLe/2 27.3105 KN

Beam depth
M = R bd2
Where R= 0.65 for M15 concrete and tor steel

d = (M/Rb)2 434.8249 mm
Assume cover to reinforcement 40 mm
Beam total depth = d+cover+8 482.8249 mm Say 900mm

Assumed beam depth = 554.00 mm

Therefore beam effective thickness(d) = 509 mm

Steel required
Ast = M/pstxjxd
j is lever arm = 0.904 for M15 concrete and tor steel

Ast = 348.37692 mm2

Minimum amount of steel required 0.25% of Ac


= 346.25 mm2

Provide 6 no. of 20 mm bars = 1885 mm2 greater than required, OK

Distribution steel 0.15% of Ac 249.3 mm2

Provide 10 mm bars 315 mm c/c on both faces of the beam


adopt = 90 mm c/c
Check shear stress

qv = SF/bd = 0.18 N/mm2

Check for shear reinforcement


100xAs = 1.23
bd
Permissible shear stress in concrete qc = 0.28 N/mm2

The shear stress is more than permissible shear stress, let us provide nominal shear reinforcement in the beam as vertical sti

Asv/bsv > 0.4/fy


For tor steel fy = 415 N/mm2, and spacing of 200 mm

Asv = 0.4x300*300/415 57.83 mm2

Provide 8 mm two legged vertical stirrup @ 10mm c/c (Asv=2x 100.4 mm2

OK
ment in the beam as vertical stirrups

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