Beam Design and Drawing of RCC Structures

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Design and drawing of RCC
Structures
SHUBHAMCE2014,
Civil Engineering Department,
UPTU, LUCKNOW,
Mob: 7906743940
Email:
shubhamce2014@gmail.com

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Learning out Come
• Introduction
• Simply supported rectangular beams
• Continuous rectangular beams
• Cantilever rectangular beams
• Flanged beams

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Introduction
• Carries Transverse External Loads That
Cause Bending Moment, Shear Forces And In
Some Cases Torsion
• Concrete is strong in compression and very
weak in tension.
• Steel reinforcement is used to take up tensile
stresses in reinforced concrete beams.
• Mild steel bars or Deformed or High yield
strength deformed bars (HYSD)
• HYSD bars have ribs on the surface and this
increases the bond strength at least by 40%

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•Drawinsg generally include a bar
bending schedule
•The bar bending schedule describes the
length and number, position and the
shape of the bar
Introduction
Sl.No.
Type of
bar and
mark
Shape No.
Length in
m
Weight
per unit
length
in Kg
Weight
in Kg

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•Anchorage in steel bars is normally
provided in the form of bends and hooks
•The anchorage value of bend of bar is
taken as 4 times the diameter of bar for
every 450 bend subjected to maximum of
16 times the diameter of bar.
Introduction

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• The beams are classified as:
• According to shape: Rectangular, T,
L, Circular etc
• According to supporting conditions:
Simply supported, fixed, continuous
and cantilever beams
• According to reinforcement: Singly
reinforced and doubly reinforced
Introduction

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• Minimum cover in beams must be 25
mm or shall not be less than the
larger diameter of bar for all steel
reinforcement including links.
• Nominal cover specified in Table 16
and 16A of IS456-2000 should be
used to satisfy the durability criteria.
Introduction

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Generally a beam consists of following steel
reinforcements:
•Longitudinal reinforcement at tension and
compression face.
•Shear reinforcements in the form of vertical
stirrups and or bent up longitudinal bars are
provided.
•Side face reinforcement in the web of the beam
is provided when the depth of the web in a beam
exceeds 750 mm. (0.1% of the web area and shall
be distributed equally on two faces at a spacing
not exceeding 300 mm or web thickness
whichever is less)
Introduction

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Specification for the reinforcement in beams is given in
clause 8.1 to 8.6 of SP34

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Different forms of stirrups used in beams

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Typical drawing of a simply supported beam

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PROBLEM No. 1
Draw the Longitudinal section, cross section and prepare bar
bending schedule of a rectangular simply supported RCC beam with
the following data:
Clear span =3.5m
Width of beam = 220mm
Overall depth of beam = 300mm
Bearing width in support = 200 mm
Main reinforcement = 5 Nos -12 mm diameter bars with 2 bars bent
up at L/7 from centre of support
Anchor/hanger bars= 2-10 mm diameter
Stirrups = 6 mm diameter @ 200 mm c/c.
Materials : Mild steel, M20 grade concrete

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PROBLEM No. 1 contd.
Bar Bending Schedule:
Bottom straight bar (12 dia)= Total length of beam +2 x16 φ-2 x 3 φ
-2 x end cover
= (3500+2 x 200)+26 x 12-2 x 25 =4162≈4200 mm
Length of bent up bar (12 dia)= Length of straight bar +2 x (0.42 x
depth of bend) =4162+2 x 0.42 x 250 =4372≈4400 mm
Length of hanger bar (10 dia)= Length of straight bar =4162≈4200 mm
Stirrups:
Number of stirrups = Length of bar (end to end)/c/c distance of
stirrup= [(3500+2x200)-2x25]/200 = 17
Length of stirrup = 2 ( A+B)+24 φ of stirrup = 2x(250+170)+24 x 6
= 984 mm ≈ 1000 mm

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PROBLEM No. 2
Draw the Longitudinal section, cross section and
prepare bar bending schedule of a rectangular simply
supported RCC beam with the following data:
Clear span =4.5m
Main reinforcement = 5 Nos -18 mm diameter bars with 2 bars
bent up at 900mm from inside of each end support
Concrete cover = 25 mm
Materials : HYSD bars, M20 grade concrete

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PROBLEM No. 2 contd.
Bar Bending Schedule:
Bottom straight bar (18 dia)= Total length of beam -2 x end cover
= (4500+2 x 200) -2 x 25 =4850 mm
Length of bent up bar (18 dia) = Length of straight bar +2 x (0.42 x
depth of bend) =4850+2 x 0.42 x 250 =5050 mm
Length of hanger bar (12 dia)= Length of straight bar =4850 mm
Stirrups:
Number of stirrups = Length of bar (end to end)/c/c distance of
stirrup = [(4500+2x200)-2x25]/200 = 24.25 ≈ 25
Length of stirrup = 2 ( A+B)+24 φ of stirrup
= 2x(250+200)+24 x 6 = 1044 mm ≈ 1100 mm

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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 in intermediate supports = 200 mm
Main reinforcement = 4 Nos -12 mm diameter bars with 2 bars bent up
Materials : HYSD bars and M20 grade concrete

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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. 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. 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.

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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
Draw longitudinal and cross section if the beam is
1. T-beam
2. Inverted T-beam
3. L-Beam

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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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