The PPT is prepared to create awareness in practicing civil engineers to minimize the mistakes in construction so as to enhance the stability and durability of structures

1. A warm Welcome to ‘U’all
1

2. A talk on Dos & Donts
In Civil constructions.
2
By Prof. V.H.Jadhav
M.Tech (Str)
Adjunct Professor K.L.E T.U Hubballi
&
Retd.TechnicalAdvisor,
HDBRTSCO. LTD
Email: Vithal.jadhav@kletech.ac.in

3. A very important subject and interesting also
3
Reinforcement detailing

4. I. S. 800-1963 - Code of Practice for use of
Structural Steel in General Building
construction.(I-1956)
4
Reinforcement

5. I.S. 800-1963 - Code adopted on 2nd April
1962 by the Indian Standard Institution
after the draft finalised by the Structural
Engineering Sectional Committee had
been approved by the Structural and Metal
Division Council and the Building
Division Council.
This standard was the first of a series of IS
published under ISI Steel Economy
Programme. (Object- to achieve economy
–rational-efficient-optimum std.s in steel
usage)
5

6. IS. 800-1963 – In the formulation of this code
assistance from the following was taken:
 IRS CP3-1958:Code of pra.for the Dgn of
Steel Stru. Other than Bridges. Ministry of
Railways Govt. of India.
 B.S-449-1959 Use of Str.steel in Blds
(B.S.I)
 CP 113-1948 Structural use of Steel (BSI)
 ASA & Erection of Steel in Blds
6

7. IS: 226-1962 (Specification for structural steel
(standard quality).
IS : 2062 -1962 Specification for Structural steel
(Fusion WeldingQuality)
IS : 1977 -1962 Structural Steel (Ordinay)- Producers
guarantee a min. yield stress of 26.0 kg/mm2 and min.
% of Elongation of 23 on a guage length of 5.65√A
(Products other than Sheet, Strip, Wire andTube)
IS : 801-1958 Use of cold formed light gauge steel
structural members in bldgs.
7

8. IS: 803 – 1962 Design of vertical mild steel
Cylindrical Welded Oil storage tanks.
IS 806 - 1957 – Use of steel tubes in general Bld
construction.
IS 807 - 1963 – Design of cranes and Hoists , Part I
(Structural)
IS 1148 – 1957 Rivet Bars for Str.Purpose
IS 1149 - 1957 High tensile Rivet bars bolts and nuts.
(Min. tensile strength of 58kg/mm2)
8

9. Before I start with Reinforcement Detailing , let me
say something about the reinforcing bars, being used in
various structures, to give due emphasis to good
construction. What is an Iron and a Steel, and how to
identify the types of bars, from their physical
appearance?
9

10. Metal,
10
Iron :-The strong magnetic silver-gray
(the element Fe) of atomic number 26,
Steel: The iron containing a little carbon ‘C’ with or
without other Composition. More the ‘C’ more the
hardness and hence becomes more brittle
Stainless steel : This is a form of steel containing
chromium(element), resistant to tarnishing and rust.
Tarnishing : lose of shining on exposure
Iron and Steel

11. 415N/mm2 500N/mm2Tor,
M S 250 N/mm2
11
Ribbed bars give 3 to 4 times >
round bars
Fe415,500 have 15 to 12.50 %elongation
C < 0.25 gives excellent bend ability
C > 0.25 generally unsuitable for welding
Oxyacetylene welding is not recommended
Due to repeated loading, stress develops
To avoid - Proper cover to be given,
for Cracks < 0.1 - 0.20 mm -no corrosion
takes.
Temp > 500o to 600o C ten. Strng. reduces230N/mm2
“Structural requirements of Steel”
Tensile strength
Bond strength
Ductility
Bend ability
Weldability
Fatigue strength
Corrosion
Fire resistance

12. The steel should have desired Mechanical properties and
Chemical properties.
Mechanical properties : Strength, Ductility, Bendability
Chemical components: Sulphor (S) and Phosphorus (P)
which are harmful impurities and reduce the strength of
the steel un extreme hot and cold conditions. Therefore
lowering the contents makes the steel better.
70% rebar in India are manufactured by crude process
from scrap by Induction Furnace Route.(increases
impurities said above)
Rebar are now introduced as “D” for example 500D
where combined Sulphor and Phosphorus is restricted to
0.075%
12

13. TMT – Thermo-MechanicalTreatment
Iron ore Blast
Furnace
Hot
Metal
BOF
Steel
Making
Liquid
Steel
Ladle
Furnace
Continuous
caster
Billets
Hot rolling/ Thermo
Mechanical Treatment
Testing
Marketting
13

14. Ref: I S 456 – 2000 & Proceedings of the 3 day
Workshop on Construction with Emphasis on
reinforcement, at Dharwad on 8th,9th & 10th
May 1995 & National Seminar on Concrete
Sructures in Challenging Environments on 21st
and 22nd at Hubli byICI
14

15. TOR 40
Fe 415
TISCON 40
CTD 40
TMT 40
Fe 500 / 500D
TOR 50
TISCON
500
Fe 550
TORKARI
MESH
“Reinforcing bars classified as grades”
TMT
15

16. CONCLUSION FOR
Fe 415 and Fe 500 / 500D ribbed / twisted bars satisfy all the
structural design requirements for conventional structures
Structural requirements of steel
16

17. Now let us Study about Cement
17

18. Cement
Cement selection should be appropriate for the intended use
18
i) 33 grade O.P.C. conforming to
ii) 43 grade O.P.C --do--
iii) 53 grade O.P
.C --do--
IS 269
IS 8112
IS 12269
iv) Rapid hardening portlant cement -- IS 8041
v) Port land slag cement -- IS 455
vi) Portland pozzolana cement(fly ash based)-IS 1489 part I
vii) --- Do----- (Calcinded clay based )
viii) Hydrophobic cement
ix) Low heat portland cement
x) Sulphate resisting portland cement ---
-- IS 1489 part II
--- IS 8043
--- IS 12600
IS 12330

19. 15 mm
Slab
Walls 15 mm
Beams (main bars) 25mm/dia
Stirrups in beams 15 mm
At end of main bar 25 mm
Columns D up to 200
D > 200
25mm
40 mm /dia
Ties in columns 15 mm
Let us look at some basic aspects.
Minimum Cover to concrete.(For general structures)
( Referance Clause 25 I.S 456 - 2000)
19

20. 50 mm
On prepared earth 75 mm
Chemical industries As above +15 mm > 75 mm
Water retaining structure As above Min 25 mm
Sea shore structures As above + 40 mm > 75
On C.C bed
For easy way of adopting the covers recommended ,
use readily available Cover Blocks as U can see
some of the models now.
Contact No., for cover blocks : 9448372469 Mr Pramod Zalakikar
20

21. Nominal Cover, to meet Durability Requirements
based on exposure conditions
21
Exposure Min. Nominal concrete cover in
mm
Mild
Moderate
Sever
Very sever
Extreme
20
30
45
50
75

22. Many
structures
22
times
are
though
properly
the R.C.C
designed,
buildings may fail because of improper
bar bending /
construction. Therefore this is
methodology in
an
important aspect for all field Engineers.
Proper bar bending methodology will
definitely improve the quality of the
structure.
Let us see some basics

23. Basic common bends of bars
In slabs Bottom
bar
Top bar
In
Beams
Cranked
bar
Bottom
bar
Top bar
Cranked
bar
Bent up
bar
23

24. Basic bends of bars
Normal
Stirrups
Single leg
Stirrup
24
Nominal
Tie
Seating
bar
Column

25. Standard bends and hooks
4d
8d
90o 135o
4d
6d
90o Bend 135o 180oHook
Hook
Various forms of links
180o
25
4d
d = dia. of bar

26. Stirrups in beams
26
Single Leg Double Leg open Double Leg
partial open
Multi Leg
Double Leg
closed
Double Leg
welded

27. Typical ties in column
27
Single tie Single leg with
single link
Diamond tie with
single tie
Double ties
Double tie Single tie double link
Note: Dotted lines indicate the position of hooks one after the other in
clockwise direction to have ductility at all corners

28. Stirrups (Loops) in Corbels
Cross bar
Main steel
Main steel
Horizontal loops
Column
Horizontal loops
Main steel
Inclined
stirrups
Column bar
Main steel
Inclined loops
28

29. Detailing in tension members
1) Bars must be welded or mechanically spliced
or
Lap length / development length should be doubled.
= 2Ld
2) In the lapped region, spirals should be provided
with pitch 100 mm
or
The spacing of ties should be reduced to ½ x b
( i.e., ½ x least dimension)
29

30. 3) Spacing of ties
diameter of ties
30
b and
6mm
Note: However it is advisable to avoid lapping in
tension members

31. Slab
15 mm
15 mm to stirrups
25 mm to main bars
Beam
40 mm
Column
R.C.C Wall
Note : Zig Zag arrangement
31
Concrete covers

32. 32
Treated Fabricated Bars
at site

33. Let us see best example of a
building whose all components
are failed.
33

34. 34

35. 35

36. 36

37. 37

38. 38

39. 39

40. 40

41. Min. and Max. reinforcement
41
TensionAst.
Compression Asc.
Side reinforcement
where web >750mm
Min &Max. spacing of
stirrups
Slab Main
Distribution
Max.&Min dia. of bars
=
AS 0.85
MIN. MAX.
0.04bD
0.15% M..S. &
0.12 Tor
1/8th total th. slab
8 mm main
2%
bd
0.33 Ast
0.1% web
fy (4%)
0.04bD
Todesign
area
80 mm
0.75 de or
450 mm

42. Development length (Ld) of bars
Ld =
O σs
4 Tcbd
O = Nominal dia of bar
σs = Stress in bar at the section in design
Tc bd = Design bond stress given table 26.2.1.1
of IS 456 - 2000
42

43. Anchorage length of bars
The anchorage length of straight bar in compression shall be equal to the
development length of the bars in compression
al al
al
43

44. Anchorage length
44
Tension
Compression
M15 M20 M25
50 x d 45 x d 40 x d
45 x d 40 x d 35 x d
Where d = diameter of the bar

45. Development length (Ld) of bars (Tor 40) values
in cms
Tension Compression
O in mms M15 M20 M25 M30 M15 M20 M25 M30
6 34 29 25 23 28 24 20 19
8 46 38 33 30 37 31 27 24
10 57 47 41 38 46 38 33 31
12 68 57 49 46 55 46 40 37
16 91 76 65 61 73 61 52 49
20 113 94 81 76 91 76 65 61
25 141 118 101 94 113 95 81 76
45

46. Durability of concrete
Durable concrete is the one which performs satisfactorily in the
working environment.
Main factor influencing the durability is permeability to the
ingress of water,oxygen,carbon dioxide,chloride,sulphate etc.,
in addition to this, following factors also influence the durability
i) the environment
ii) the cover embedded to steel
iii) the type and quality of constituents materials
iv) Water / Cement ratio.(Table 5 of IS 456 - 2000)
v)workmanship to obtain full compaction and 100% curing
vi)the shape and size of the member.
46

47. Grades of concrete Fine and coarse
agget.by mass per
50 kg cement
Proportion of fine
and coarse agget.
Qty of water/50kg
cement in ltr
M5 800 Generally 1:2 60
M7.5 625
but subject to
an upper limit 45
M10 480 of 1:11/2 and
lower limitof
34
M15 330 1:21/2 32
M20 250 30
For an average grading of fine aggregate (i.e., Zone II ) Proportion shall be 1:1 1/2,
1:2 , 1:2 1/2
Proportion for Nominal Mix Concrete
Note:For design mix = refer lab values
47

48. Concrete Mixing
48
Mixing :- Shall be mixed in a mechanical mixer.
The mixer should comply with IS 1979 and IS
12119 & shall be fitted with water measuring
(metering) devices. The mixing shall be continued
until the mass is uniform in colour and consistency.
If there is segregation after unloading from the
mixer, the concrete should be re mixed.
For guidance, the mixing time shall be at least 2min
For hydrophobic(fear of water) cement it may be
decided by the Engineer- in -charge.
Dosage of retarders, plasticisers and superplastercisers sall be
restricted to 0.50,1.0 and 2.0% based on performance test.

49. Types of Concretes
49
Do we know how many types of concretes are there? 65
Special concretes using Portland Cement as binder
1. Air entrained Concrete
2. Celluar Concrete.
3. Architectural Concrete
4. Centrifugally Cast Concrete
5. Colloidal Concrete
6. Coloured Concrete
7. Controlled Concrete
8. Cyclopean (rubble) Concrete
9. Dry Packed Concrete
10. Epoxy - modified Concrete
11.Exposed aggregate Concrete
12.Ferro Cement Concrete

50. 13. Fiber - reinforced Concrete
14. Fill Concrete
15. Flowing Concrete
16. Fly Ash Concrete
17. Gap – graded Concrete
18. Heavy Weight Concrete
19. High early strength Concrete
20. High strength Concrete
21. High performance Concrete
22. Insulating Concrete
23. Latex Modified Concrete
24. Low - density Concrete
25. Mass Concrete
26. Moderate strength light weight Concrete
27. Nail able Concrete
28. No-Slump Concrete
50

51. 29. Polymer – modified Concrete
30. Porous Concrete
31. Pozzolona Concrete
32. Pre Cast Concrete
33. Pre – placed aggreagte Concrete
34. Pre stressed Concrete
35. Rollar compacted Concrete
36. Ready Mixed Concrete
37. Saw dust concrete
38. Shielding Concrete
39. Shot concrete
40. Shrinkage compensating Concrete
41. Silica flume Concrete
42. Soil Cement Concrete
43. Structural light weight concrete
44. Super plasticised Concrete
51

52. 45. Terrazo Concrete.
46. Tremie Concrete
47. Vacuum treated Concrete
48. Vermiculite Concrete
49. White Cement Concrete
50.Lunar Concrete ( To construct structures On
Moon)
51.Bacterial Concrete?
52 Tremix concrete.
Types of Concrete not using Portland Cement 1.Acrylic Cement
Concrete
2.Aluminium Phosphate Concrete
3. Asphalt Concrete
4. Calcium Aluminate Concrete
5. Epoxy Concrete
6. Furan Concrete
7. Gypsum Concrete
52

53. 8. Latex Concrete
9. Magnesium Phosphate Concrete
10. Methyl Methacrylate Concrete
11. Polyester Concrete
12. Polymer Concrete
13. Potassium Silicate Concrete
14. Sodium Silicte concrete
15. Sulphur Concrete
53

54. DOS AND DON’TS
54
I have classified Dos and Donts in two groups
1) Dos and Don’ts in bar bending schedule
2) Dos and Don’ts in Construction.
Let me start with Dos and Donts
in bar bending schedule

55. 25 mm to main
bars
Beam
<15 mm to
stirrups
<25 mm to main
bars
Beam
Column
Single
side
< 40 mms
<
40
Column
40 mms
15 mm to stirrups
40
Dimensions in mms
Compression
Zone
55
Covers

56. In Cantilever Beam
Main ten.steel at Top
Steel in comp. at Bottom.
Ten - zone
Stirrups
Hooks in ten .zone
Hooks in com. zone
Com - zone
Main ten. steel at Bottom
56

57. Reinforcement in folded staircase
No bar
required
57

58. 58
STAIRCASE
REINFORCEMENT

59. Main reinforcement
Distribution reinforcement
Chejja
Main reinforcement
Distribution
59
reinforcement
Cantilever Slab
Ld

60. 60
In cantilevers tension will be at top and compression will be at bottom
Cantilever chejja failled due to providing main steel at bottom instead at top

61. 61
In cantilevers tension will be at top and compression will be at bottom
Cantilever chejja failled due to providing main steel at bottom instead at top

62. 62
In cantilevers tension will be at top and compression will be at bottom
Cantilever chejja failled due to providing main steel at bottom instead at top

63. 63
Corroded 16mm dia HYSD bars could be crushed by bare hand.

64. Staircase reinforcement at landing and waistslab
C.C bed block
64

65. Anchorage length
RC wall
Wall reinforcement, Wall
reinforcement,
RC wall
Reinforcement in R.C.C wall intersections
Anchorage length
65

66. Main bars Distribution bars
Main bars
Distribution bars
Reinforcement in one way slab
66

67. Tor 50
Tor 40
Tor 40
Tor 40
Alternative Tor 50 or Torkari can be used in both directions
Mixing up of bars in two way slabs
67

68. 0.3L
0.2L
L
Reinforcement in cantilever slab
See the bar-not covered full
tension zone
Cantilever
68

69. 0.3L 0.3L
0.2L 0.2L
L
Placement of bars at slab support
See the bar-not covered full
tension zone
69

70. Continuity of bars in columns
Development
length
Development length
not staggered
Development
length
70

71. Construction joint in Column
71
Smooth
surface
Rough surface

72. Very imp tie
Beam bars left
in middle
Column
bars
No tie bar
Stirrups
Bar lapping in Column - Beam junction
Note: At junction if not possible to provideconventional
tie, then make two U shape ties and then join
72

73. Abrupt kinking of bars in columns
Beam bars
Sudden kink
U shape
Stirrups and ties
73

74. Defective provision of Ties in columns
Beam bars Beam bars
Tie
prefered
Tie at beam
level is a must
No Tie
provided
74

75. Or
Recommended
weld length
Insufficient weld length
Discontinuity of bars in columns
75

76. Bars left for extension in columns
Straightening of
bars in future Bent at top
Bar coated
with rich zinc
primer
76

77. Ld
Ld
Welded Joint
2Ld Stirrups @ 1/2 of usual spacing
77
Note: However it is advisable to avoid lapping in Tension members
Lapping of bars in Tension member

78. >0.2L >0.2L
0.1L 0.1L
Ast
About-12 Dia
Curtailment of bars in beams
78

79. < 20 o o
Min 300 mms
Details of footing
F > 20 0 Double form work to beprovided.
Min 300 mms
79

80. DOS AND DONTS IN CONSTRUCTION
80
Buildings may fail because of defective
construction. Therefore it is very essential
to know the
Dos and Don’ts in construction also.
(It is preferred to know Don’ts first)

81. Construction joint in Slab
x =1/3 to 1/4 th span
WPC
81

82. Construction joint in Beam Column Junction
M15 M15
M20
M20
M20 300
Min
M15 A
B
M20
M15 A
M20
M15
M20 300
Min
M15 A
B
M20
M20
Arrows indicate further
concreting
82

83. Construction joint at Beam Column Junction
Indicates direction of concreting
83

84. Footings
Kicker
/Starter
Kicker or
Starter
Kicker : Optional
Rough
surface
20 o Epoxy
coatingViz.,
Nito bond
84

85. Construction joint at Beam Column Junction
x
85

86. 86
Un plastered portion is the way for water to percolate and to disintegrate the
structure

87. 87
Un covered hole used for scaffolding is the way for water to percolate and to
disintegrate the structure

88. 88
Facia provided for balcony without sufficient drain pipe has become water pond
During mansoon

89. 89
Waste material dumped on terrace will allow the plants to grow and
Makes the slab to leak.

90. 90
Un covered Asbestos sheets lead to leakage and dampness of walls

91. Rich fillet M20
Horizontal Strip wise
M15
Centering
Indicates direction of concreting
L
Concreting should be in horizontal
strips from beam towards ridge.
Note: Minimum details shown to have clarity
Concreting in sloped slab / beam
91

92. Steps to be followed while and after
concreting in sloped slab / beam
92
1)Centering should be strong enough with sufficient supports.
Supporting in opposite direction of the slope also is amust.
2) Horizontal ties should be provided for supports.
3) Water cement ratio shall be maintained.
4)Concreting shall be done from “end beam” towards “top”(ridge), in
horizontal strips of width less than the length of the tampers (Godas).
5) Rich fillet shall be provided at ridge portion.
6)Immediately after concreting, slab shall be broomed with cement
slurry and then shall be plastered with WPC. (Algae proof has given
good result)
7)On very next day, early in the morning again slab shall be broomed
with cement slurry to patch up the micro cracks.

93. Construction joint in one way Slab
93

94. W
L L1
0.2L 0.15L2
L2
0.2L2
0.2L1
0.2L1
0.2L
0.3L 0.3L 0.3L1 0.3L1 0.3L2
Typical Bar bending schedule for slab, with fixed,
continuous & simply supported end conditions.
W
Fixed emd
W
Continuos support
W
Simply supported
94

95. Slab /
RB
Slab /RB
150
50
WPC sloping both sides
WPC fillet
WPC fillet
Thin Tar felt/paper
Expansion pad
300
150 120
A typical Expansion joint in final roof slab
/ Roof Beam recommended - by me.
M20/M15
M20
M20
Nominal Lintel with 4 6 dia
M.S.bars
95

96. Roof beam
Roof beam Roof beam
Roof beam
Column
Column
Column
Column
Plan
Elevation
Expansion joint in Columns
Expansion joint over final
roof beams
P.V.C down take cut pipe
P.V.C down take cut pipe
hooked in to roof beamand
wall
96

97. L
0.3L/2
0.2L/2
Minimum details shown to have clarity
Eb
Eb
0.2L/2
Centering
Bar scheduling in sloped slab /beam
Rich fillet
0.3L/2
End beam may be of this
shape also
97

98. THANK Q
98