Friday, November 20, 2015
Detailed Process for effective slab reinforcement
This construction video will highlight the detailed process for complicated slab reinforcement. All steel bars are connected following the design details. Here the concrete ratio is 1:2:4. This video is very useful for Civil Engineering students as well as various structural engineering professionals.
The slabs containing ratio of longer length to its shorter length (Ly/Lx) larger than 2 is known as one way slab or else as two way slab. In one way slab main reinforcement is equivalent to shorter direction and the reinforcement equivalent to longer direction is defined as distribution steel. In two way slab main reinforcement is rendered alongside both direction.
Detailing Requirements of RCC Slab as per IS456: 2000
a) Nominal Cover:
For Mild exposure – 20 mm
For Moderate exposure – 30 mm
However, if the diameter of bar is less than 12 mm, or cover may be decreased to 5 mm. Therefore for core reinforcement up to 12 mm diameter bar and for mild exposure, the nominal cover will be 15 mm.
b) Minimum reinforcement: The reinforcement in either direction in slab must not be lower than
• 0.15% concerning the total cross sectional area for Fe-250 steel
• 0.12% concerning the total cross-sectional area for Fe-415 & Fe-500 steel.
c) Spacing of bars: The utmost spacing of bars must not surpass
• Main Steel – 3d or 300 mm whichever is lesser.
• Distribution steel –5d or 450 mm whichever is lesser Where, ‘d’ denotes the operative depth of slab. Note: The least clear spacing of bars must not be lower than 75 mm (Preferably 100 mm) even if code does not suggest any value.
d) Maximum diameter of bar: The maximum diameter of bar in slab, must not surpass D/8, where D denotes the total thickness of slab.