This document provides problems and examples related to detailing of beams and slabs in reinforced concrete structures. It discusses concepts like continuous beams, cantilever beams, flanged beams, one-way slabs, and two-way slabs. Seven problems are presented involving drawing the longitudinal section and cross sections of beams and slabs and showing reinforcement details. The document concludes with two problems for the reader to solve involving preparing bar bending schedules and estimating quantities of steel and concrete.
3. 3
Learning out Come
โข Review of detailing of beams
โข Continuous rectangular beams
โข Cantilever rectangular beams
โข Flanged beams
โข Introduction to detailing of slab
โข One way slab
5. 5
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
7. 7
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.
10. 10
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
12. 12
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
15. 15
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
18. Dr.G.S.Suresh18
Introduction
โข Used for covering spaces in the
form of roof or floor
โข Slab may be supported on walls or
beams or columns .
โข Slab supported directly by columns are
called flat slab
โข One Way Slab
โข Two Way Slab
19. Dr.G.S.Suresh19
Introduction
โข Slabs could be simply supported,
continuous or cantilever
โข In two way slab the corners may be held
down by restraints or may be allowed to
lift up
โข Additional torsion reinforcement is
required at corners when it is restrained
against uplifting as shown in Fig
21. Dr.G.S.Suresh21
Introduction
โข 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.
โข The maximum diameter of bar used in slab
should not exceed 1/8 of the total thickness of
slab
โข Maximum spacing of main bar is restricted to
3 times effective depth or 300 mm which ever
is less
โข For distribution bars the maximum spacing is
specified as 5 times the effective depth or 450
mm which ever is less
22. Dr.G.S.Suresh22
Introduction
โข Generally 15 mm to 20 mm cover is
provided for the main reinforcements
โข 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
โข Curtailment and cranking of bars and is
shown in Fig
29. 29
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
30. 30
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
38. 38
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.
39. 39
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.
40. 40
Dr. G.S.Suresh
Civil Engineering Department
The National Institute of Engineering
Mysore-570 008
Mob: 9342188467 Email: gss_nie@yahoo.com
