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Design and drawing of RC
Structures CV61
Dr. G.S.Suresh
Civil Engineering Department
The National Institute of Engineering
Mysore-570 008
Mob: 9342188467 Email: [email protected]
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DETAILING OF
BEAM &SLAB
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Learning out Come
• Review of detailing of beams
• Continuous rectangular beams
• Cantilever rectangular beams
• Flanged beams
• Introduction to detailing of slab
• One way slab
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PROBLEM No. 3 Draw the Longitudinal section and two cross sections one near the support and other near the mid span of a RCC continuous beam with
the following data:
Clear span of beams = 3m each
Width of beam = 200mm
Overall depth of beam = 300mm
Width in intermediate supports = 200 mm
Main reinforcement = 4 Nos -12 mm diameter bars with 2 bars bent up
Anchor/hanger bars= 2-10 mm diameter
Stirrups = 6 mm diameter @ 300 mm c/c.
Materials : HYSD bars and M20 grade concrete
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PROBLEM No. 3
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PROBLEM No. 4 A rectangular beam of cross section 300 x 450 mm is
supported on 4 columns which are equally spaced at 3m
c/c. The columns are of 300 mm x 300 mm in section. The
reinforcement consists of 4 bars of a6 mm diameter (+ve
reinforcement) at mid span and 4 bars of 16 mm diameter at all supports (-ve reinforcement). Anchor bars consists of a
2-16 mm diameter. Stirrups are of 8 mm diameter 2 legged
vertical at 200 c/c throughout. Grade of concrete is M20 and
type of steel is Fe 415.
Draw longitudinal section and important cross sections.
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PROBLEM No. 4
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PROBLEM No. 5 Draw to scale of 1:20 the Longitudinal section and two cross-section of a cantilever beam projecting 3.2 from a support using
following data
Clear span =3.2m
Overall depth at free end = 150 mm
Overall depth at fixed end = 450 mm
Width of cantilever beam = 300 mm
Main steel = 4-28 mm dia with two bars
curtailed at 1.5m from support
Anchor bars = 2 Nos. 16 mm dia
Nominal stirrups = 6mm dia at 40 mm c/c
Bearing at fixed end = 300 mm
Use M20 concrete and Fe 415 steel
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PROBLEM No. 5
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PROBLEM No. 6 A cantilever beam with 3.2m length is resting over a masonry wall and
supporting a slab over it. Draw to a suitable scale Longitudinal section,
two cross-sections and sectional plan with the following data:
Size of beam = 300 mm x 350 mm at free end and 300 mm x 450 mm at
fixed end and in the wall up to a length of 4.8m
Main steel: 4 nos. of 25 mm dia bars, two bars curtailed at 1.2m from
free end
Hanger bars: 2 nos. 16mm.
Stirrups: 6mm dia 2 legged stirrups @ 200 mm c/c the support length
and @100 mm c/c from fixed end up to length of 1m @ 150mm c/c up to
curtailed bars and remaining @ 200 c/c.
Use M20 concrete and Fe 415 steel
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PROBLEM No. 2
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PROBLEM No. 7 A beam has following data
Clear span = 4m
Support width = 300mm
Size of web = 350 x 400
Size of flange = 1200 x 120mm
Main reinforcement in two layers : 3-20 tor + 3-16 tor and to be
curtailed at a distance 400 mm from inner face of support
Hanger bars: 3- 20 tor
Stirrups: 2L-8 tor @ 200 c/c
Use M20 concrete and Fe 415 steel
Draw longitudinal and cross section if the beam is
1. T-beam
2. Inverted T-beam
3. L-Beam
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PROBLEM No. 5
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Dr.G.S.Suresh 18
Introduction
• Used for covering spaces in the form of roof or floor
• Slab may be supported on walls or beams or columns .
• Slab supported directly by columns are called flat slab
• One Way Slab
• Two Way Slab
Dr.G.S.Suresh 19
Introduction
• Slabs could be simply supported,
continuous or cantilever
• In two way slab the corners may be held
down by restraints or may be allowed to
lift up
• Additional torsion reinforcement is
required at corners when it is restrained
against uplifting as shown in Fig
Dr.G.S.Suresh 20
Introduction
Dr.G.S.Suresh 21
Introduction • Thickness of the slab is decided based on
span to depth ratio specified in IS456-2000. Min reinforcement is 0.12% for HYSD bars and 0.15 % for mild steel bars.
• The maximum diameter of bar used in slab should not exceed 1/8 of the total thickness of slab
• Maximum spacing of main bar is restricted to 3 times effective depth or 300 mm which ever is less
• For distribution bars the maximum spacing is specified as 5 times the effective depth or 450 mm which ever is less
Dr.G.S.Suresh 22
Introduction • Generally 15 mm to 20 mm cover is
provided for the main reinforcements
• Alternate main bars can be cranked near
support or could be bent at 1800 at the
edge and then extended at the top inside
the slab as shown in Fig
• Curtailment and cranking of bars and is
shown in Fig
Dr.G.S.Suresh 23
Introduction
Dr.G.S.Suresh 24
Introduction
• Torsion Reinforcement shall be provided
as shown in Fig.
Dr.G.S.Suresh 25
Torsion Reinforcement
Dr.G.S.Suresh 26
Torsion Reinforcement
Dr.G.S.Suresh 27
Typical One Way slab
Dr.G.S.Suresh 28
Typical Two Way slab
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PROBLEM Prepare a detailed structural drawing of one way continuous slab for a hall of clear dimensions 7m wide and 11.77 m long, use following data
Centre to centre distance of supporting beams = 3.0 m
Span of the beams = 7.23m
Beams are supported on walls of 0.23 m thickness
C/s of beam = 230 x 450 mm
Grade of concrete : M20
Type of steel : Fe415
Clear cover : 20 mm
Slab thickness: 150 mm
Beam depth is inclusive of slab depth, The hall is having walls on
all 4 sides
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PROBLEM Main positive reinforcement @ end span = 8mm
diameter @100 c/c
Main reinforcement in other interior panels = 8 mm
diameter @ 200 c/c
Negative reinforcement @ all supports = 8mm diameter @ 200 c/c
Distribution steel= 8mm diameter @ 200 c/c
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PROBLEM
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No. 1
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No. 2
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No. 3
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No. 4
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No. 5
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Do it Yourself
1. Draw the longitudinal section and typical cross sections ( at centre
and support), and show the reinforcement details in a simply supported
rectangular beam of size 300 mm x 500 mm, clear span 5m supported
on walls of 0.3m, use a suitable scale
Reinforcements:
Main: 4 No. 16mm dia with 2 No. cranked at 1m from centre of
support. Stirrup holders 2 Nos. of 12 mm dia
Stirrups: 2 legged 8 mm dia stirrups at 250 mm c/c in the central 2m
span and 2 legged 8 mm dia stirrups at 150 mm c/c in the remaining
portion. Assume concrete M 20 grade and steel Fe 415, and suitable
cover. Prepare the bar bending schedule and calculate quantity of steel
and concrete required.
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Do it Yourself
2. Prepare the bar bending schedule and estimate quantity of steel and
concrete after drawing the longitudinal and cross section. Other details
are
Span of beam = 4.2 m
Cross section at support end 300 x 600 mm and cross section at
free end 300 x 150 mm
Reinforcements:
Main tension steel: 4-20 mm dia, 2 bars are curtailed at a distance
of 2m from free end
Hanger bars: 1-12 mm dia
Two legged stirrups 8mm dia @ 140 mm c/c for full length.
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Dr. G.S.Suresh
Civil Engineering Department
The National Institute of Engineering
Mysore-570 008
Mob: 9342188467 Email: [email protected]
