IS 456: 2000 Provisions
26.3.3 Maximum Distance Between Bars in Tension
b) Slabs
1.The horizontal distance between parallel
main reinforcement bars shall not be more
than three times the effective depth of
solid slab or 300mm whichever is smaller.
2. The horizontal distance between parallel
reinforcement bars provided against
shrinkage and temperature shall not be more
than five times the effective depth of a
solid slab or 450mm whichever is smaller.
26.5.2 Slabs
The rules given in 26.5.2.1 and 26.5.2.2 shall apply to
slabs in addition to those given in the appropriate
clauses
26.5.2.1 Minimum reinforcement
The mild steel reinforcement in either direction in
slabs shall not be less than 0.15 percent of the total
cross-sectional area. However, this value can be
reduced to 0.12 percent when high strength deformed
bars or welded wire fabric are used.
26.5.2.2 Maximum diameter
The diameter of reinforcing bars shall not
exceed one-eighth of the total thickness of
the slab.
SP-34 Provisions
9.3.1 Slabs spanning in One direction - The
bars in the shorter direction(main bars)
are placed in the bottom layer. At-least
50% of main reinforcement provided at mid
span should extend to the supports. The
remaining 50% should extend to within 0.1l
of the support.
9.3.2 Slabs spanning in Two direction - A
simply slab spanning in two directions
(ly/lx<=2) and supported on four brick
walls is shown in FIG 2.
At least 50% of the tension reinforcement
provided at mid-span should extend to the
supports. The remaining 50% should extend
to within 0.1lx or 0.1ly of the support,
as appropriate, where lx and ly are
effective spans in the shorter direction
and longer direction, respectively.
9.3.2 Slabs spanning in Two direction - A
simply slab spanning in two directions
(ly/lx<=2) and supported on four brick
walls is shown in FIG 2.
At least 50% of the tension reinforcement
provided at mid-span should extend to the
supports. The remaining 50% should extend
to within 0.1lx or 0.1ly of the support,
as appropriate, where lx and ly are
effective spans in the shorter direction
and longer direction, respectively.
Torsion reinforcement details
Cantilever Slabs
9.4 Restrained Slabs - When the corners of
a slab are prevented from lifting, the
following simplified detailing rules may
be applied, provided the slab is designed
for predominantly uniformly distributed
9l.o4a.d1s .T h e s l a b s a r e c o n s i d e r e d a s d i v i d e d
in each direction into middle strips and
edge strips as shown in FIG 3, the middle
strip being three-quarters of the width and
each edge strip one-eighth of the width.
9.4.2 The tension reinforcement provided
at mid-span in the middle strip shall
extend in the lower part of the slab to
within 0.25l of a continuous edge,or 0.15l
of a discontinuous edge.
9.4.3 Over the continuous edges of a middle
strip, the tension reinforcement shall
extend in the upper part of the slab at a
distance of 0.15l from the support, and at
least 50% shall extend a distance of 0.30l.
9.4.4 At a discontinuous edge, negative
moments may arise. They depend on the
fixity at the edge of the slab but, in
general, tension reinforcement equal to
50% of that provided at mid-span extending
0.1l into the span will be sufficient.
9.4.5 Reinforcement in edge strip parallel
to the edge shall comply with minimum
reinforcement and the requirements for
torsion 9.4.4 to 9.4.6.2