Civil Engineering - RCC Structures Design - Discussion

Concept:
According to IS: 456 (2000),

In a simply supported slab, the minimum spacing of distribution reinforcement should be:

Maximum of (4d, 60 cm)

Important Points:
Distribution steel is provided to distribute the load in a longitudinal direction.
It also takes care of shrinkage along the transverse direction and temperature effect.

Minimum spacing of distribution steel is governed by proper anchorage of reinforcement with concrete whereas maximum spacing is governed by the independent behavior of bars.


Note: Here, the question is asking for minimum spacing, not maximum spacing (5d, 45 cm).

In a simply supported slab the minimum spacing of distribution reinforcement, should not be more than five times the effective thickness of the slab or 600mm.

In a simply supported slab the minimum spacing of main reinforcement, should not be more than three times the effective thickness of the slab or 600mm.

@Khan @Mukesh ogres.

Min thickness of slab 125mm.
As per IS 456:2000.
For distribution reinforcement min spacing 4d or 450mm whichever is less.

The minimum thickness of slab 125mm.

And spacing in case of distribution reinforcement 5d or 450mm whichever is less.

@All.
We need minimum spacing not maximum.

Distribution reinforcement 5d or 450mm is maximum.

5d or 450mm which is less for traverse. And 3d or 300mm for longitudinal bars for column.

In options the given unit should be in mm (millimeter) not in cm (centimeter).

For secondary, r/f max spacing is 5d or 300mm as per latest amendment is 456.

Answer is 30cm.

As per IS456 fourth amendment.
Maximum spacing 5d or 300mm.

Minimum spacing must be greater than 40mm considering the aggregate size.