Hot Dipped Galvanized Wire Mesh, Wire Mesh For Concrete Reinforcement, Electric Resistance Welding, Thane, India |
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Concrete Reinforcement Design Example of Welded Wire
Fabric |
Consider a slab panel of 3m x 4m
continuous on two
adjacent edges and discontinuous on the other two. Live
Load is 250 Kg/m3. Concrete is M15 grade and steel is
HYSD bars in Alternate (1) and WWF in Alternate (2).
Assume a 100 thk slab from deflection criteria as per
CI:23.1
Note-2(IS-456)
Two way Span Aspect Ratio:4/3=1.33
Effec. Depth = 80mm. Lever Arm Factor = 0.798
Limit Mom. Capacity (M15-Fe415)=1.325 Ton. m/m
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Design Loads :
Dead Load 0.1 x 2.5
= 0.25 t/m2
Floor Finish 0.05 x 2.0
= 0.10 t/m2
Live Load 0.25
t/m2
0.60 t/m2
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Design Moment = Mom. Coeff x 0.6 x 3 x 3
ton. m/m |
| Location |
Moment Coeff
as per Table -22
(IS-456/78) |
Design
Moment
(ton/m) |
HYSD-Fe480
steel area
required (mm2/m) |
WF-Fe480
Steel Area
Required(mm2/m) |
1)
Short Span -ve Mom. at continuous edge-M. |
0.067 |
0.362 |
236 |
203 |
2)
Short span -ve Mom. at mid-span-M |
0.050 |
0.270 |
176 |
152 |
1)
Long Span -ve Mom. at continuous edge-M. |
0.047 |
0.254 |
165 |
143 |
2)
Long Span -ve Mom. at mid-span-M |
0.035 |
0.189 |
123 |
106 |
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Min Steel @ 0.12%
= 120 mm2/m and spacing not more than 240mm c/c |
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DETAILING : |
1)
ProvideY8 @ 240 c/c in short-span direction
at top at continuous support with 50%
extending upto 450mm from support centre and
50% upto 900mm from support centre.
(Steel Consumed = 14.5m of Y8 = 5.72 Kgs.)
2) ProvideProvideY8 @ 240
c/c (Max.
spacing criteria) in short-span direction at
bottom throughout since it is minimum
steel.. (Steel Consumed = 51m of Y8 = 20 Kgs.)
3) ProvideY8 @ 240 c/c (max. spacing
criteria) in long-span direction at top at
continuous support with 50% extending upto
660mm from support centre and 50% upto
1200mm from support centre. (Steel Consumed
= 13.8m of Y8 = 5.42 Kgs).
4) ProvideProvideY8 @ 240 c/c(Max.
spacing criteria) in long-span direction at
bottom throughout since it is minimum
steel.. (Steel Consumed = 52m of Y8 = 21 Kgs.)
5) Provide minimum distribution steel
for shrinkage & cracking Y8 @ 440c/c to all
top steel in direction parralel to the
edge strips (Steel Consumed = 24m of Y8 =
9.42 Kgs)
6) Provide Y8 @ 300 c/c-600 long each
way top & bottom as torsion steel at 3
corners
(Steel Used = 21.6m of Y8 = 8.53Kgs.) |
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Total HYSD
Bars used 70.09 kgs Cost @ 16/kg
1124.44 |
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Binding wire
reqd. at approx. 250 bottom joints and 145
top joints with 0.18m of 1.4 dia per joints.
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0.9 kgs costs
@ 20/kg
18.00
Fitting Cutting etc. labour at 1.5/kg
105.15
Total 1247.60 |
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ALTERNATE-(2)
using WWF
1) Use 100x100-4x4mm WWF of 900 width
at top over short span continuous support.
Add 100x200-3.3x2.5mm WWF of 450mm width at
top over support. (Steel Consumed = 9.19 kgs)
2) Use 100x100-4x4mm WWF in the bottom
throughout. Add 200x200-3.0x3.0mm WWF in the
middle strip zone of 2.25m x 3m (Steel
Consumed = 28.37 Kgs)
3) Use 100x100-4x4mm WWF of 1200 width
at top over long span continuous support.
(Steel Consumed = 8.79 kgs)
4) Provide 600 x 600-100x100x3x3 top &
bottom layers WWF as torsion steel at two
corners with one edge discontinuous. (Steel
Consumed = 3.13 Kgs)
Total WWF used = 49.48 kgs Cost @ 21/kg =
1039.08
Savings achieved by use of WWF = Rs. 208.51
or 16.71 of cost with HYSD detailing.
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