Design and drawing of RC Structures CV61

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Design and drawing of RC StructuresCV61
Dr. G.S.Suresh Civil Engineering Department The
National Institute of Engineering Mysore-570
008 Mob 9342188467
Email gss_nie_at_yahoo.com
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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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CONTINUOUS RECTANGULAR BEAMS
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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 _at_ 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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CANTILEVER RECTANGULAR BEAMS
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• PROBLEM No. 5

Draw to scale of 120 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 _at_
200 mm c/c the support length and _at_100 mm c/c
from fixed end up to length of 1m _at_ 150mm c/c up
to curtailed bars and remaining _at_ 200 c/c. Use
M20 concrete and Fe 415 steel
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• PROBLEM No. 2

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FLANGED BEAMS
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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 _at_ 200 c/c
• Use M20 concrete and Fe 415 steel
• Draw longitudinal and cross section if the beam
  is
• T-beam
• Inverted T-beam
• L-Beam

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• PROBLEM No. 5

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DETAILING OF SLAB
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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

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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

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Introduction
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

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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

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Introduction
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Introduction

• Torsion Reinforcement shall be provided as shown
  in Fig.

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Torsion Reinforcement
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Torsion Reinforcement
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Typical One Way slab
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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 _at_ end span 8mm
diameter _at_100 c/c Main reinforcement in other
interior panels 8 mm diameter _at_ 200
c/c Negative reinforcement _at_ all supports 8mm
diameter _at_ 200 c/c Distribution steel 8mm
diameter _at_ 200 c/c
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• PROBLEM

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ILLUSTRATIONS
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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 _at_ 140 mm
c/c for full length.
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GOOD DAY
Dr. G.S.Suresh Civil Engineering Department The
National Institute of Engineering Mysore-570
008 Mob 9342188467
Email gss_nie_at_yahoo.com