 Steel has enabled grand structures both past and present due to its strength and versatility. It is commonly used in transmission towers, industrial buildings, bridges, storage structures, and water tanks.  The document outlines the syllabus for a course on design of steel structures using the limit state method, covering topics such as connections, tension and compression members, beams, and column bases.  Steel is a versatile structural material due to its strength, lighter weight, faster construction, and ductility which provides good earthquake resistance compared to other materials. The document discusses steel's material properties and composition as well as common sections used in design.

1. Introduction to
DESIGN OF STEEL STRUCTURES
(Limit State Method)

2. 1

3. Introduction
Steel has made possible some of the grandest structures both inthe past
and in the present days
 Structural steel is widely used in making:
 Transmission towers
 Industrial buildings
 Bridges
 Storage structures
 Water tanks

4. Anatomy
Beams
Columns
Floors
Bracing
Systems
Foundation
Connections

5. 3

6. Syllabus
Module 1: Introduction:
Steel as Structural Material; Advantages and disadvantages of
steel; Types of sections , I. S. Rolled Sections; Material
Overview, Basis for Structural Design; Loadings and Load
Combinations
Module 2: Connections:
Types of Connections, Bolted Connections; Advantages and
disadvantages of bolted joints Design of bolted connections;
Efficiency and design of joints; Welded Connections;
Advantages and disadvantages of welded joints, Design of

7. welded connections; Fillet and butt welds, Plug and slot welds
4

8. Module 3: Eccentric Connections
Types of eccentric connections, Bolted and weld connections,
load lying in plane of joint, load lying perpendicular to the plane
of joint, Design of eccentric connection using bolts and welds
Module 4: Tension Members
Types of failures, Gross and net sectional area, Rupture of
critical section, Strength calculation; Block shear failure,
Slenderness ratio, Design of tension members; Gusset plates,
Lug angles; tension splices; Design of tension member
subjected to axial and bending

9. 5

10. Module 5: Compression Members
Types of failures, Strength calculation ; slenderness ratio, Design of
compression member; Design of eccentrically loaded compression
member; Built-up compression members; Design of built-up
compression members; Design of lacing system; Design of batten
plate
Module 6: Flexural Members
Introduction to flexural members: Beams; Design procedure of beam
members; Design of laterally supported beams; Design of laterally
unsupported beams; Built-up beams; Design of purlins
Module 7: Column Base
Slab Base, Gusseted Base
Module 8: Gantry Girders

11. Codal aspects on design criteria on gantry girder
6

12. Design of Steel Structures
Dr. Subramanian Narayanan - Oxford Publication
Limit State Design of Steel Structures
S. K. Duggal –Tata McGraw Hill
Text Books/References

13. 7

14. Design of Steel Structures
by Elias G. Abu-Saba
– CBS Publishers and Distributors
Design of steel structures
by E.H. Gaylord, C.N. Gaylord
& J.E. Stallmeyer – McGraw Hill.
Structural Steel work: Analysis and Design
by S. S. Ray – Blackwell Science
Text Books/References

15. 8

16.  Code of practice for general construction in
steel  IS: 800 - 2007
 Handbook for structural engineers
 SP: 6(1) – 1964 (Reaffirmed 2003)
 IS 808 : 1989 (Reaffirmed 2004)
 Steel Tables of any standard publication.
 Code of practice for design loads (other than
earthquake) for buildings and structures
Codes

17.  IS 875 : Part I to V : 1987
 IRC for vehicle load etc. in Bridge structures
9

18. ROLLED STEEL SECTIONS
Indian Standard Junior Beam (ISJB) – JB
Indian Standard Light Beam (ISLB) – LB
Indian Standard Medium Weight Beam (ISMB)– MB
Indian Standard Wide Flange Beam (ISWB) – WB
Indian Standard Heavy Weight Beam (ISHB)– HB
Indian Standard column section (ISSC) – SC

19. 10

20. ROLLED STEELSECTIONS
I-Section

21. 11

22. Channel – Sections
Indian Standard Junior Channel (ISJC) – JC
Indian Standard Light Channel (ISLC) – LC
Indian Standard Medium Weight (ISMC) – MC
Indian Standard parallel flange Channel (ISMCP)-MCP

23. 12

24. Angle – Sections
Indian Standard Equal Angel (ISA)
Indian Standard Unequal Angel (ISA)

25. Angle section

26. Tee – Sections
Indian Standard Normal Tee Bars (ISNT) – ISNT – NT
Indian Standard Deep Tee Bars (ISDT) – ISDT – DT
Indian Standard Light Tee Bars (ISLT) –ISLT – LT
Indian Standard Medium Tee Bars (ISNT) –ISMT – MT
Indian Standard Heavy Tee Bars (ISHT) –ISHT – HT

27. 15

28. Rolled Steel Bar Section
Indian Standard Round Section-ISRO
Indian Standard Square Section-ISSQ

29. 16

30. Rolled Steel Sections are designated as follows
ISRO100 means a round section of diameter 100mm,
while ISSQ50 means a square section each side of
which is 50mm.

31. 17
100mm 50mm

32. Rolled Steel sheets & strip
Indian Standard Steel Sheet Section- ISSH-SH
Indian Standard Steel Strip Section- ISST-ST
Rolled steel flats are designated by width of
the section in mm followed by the letter F &
thickness. Thus, 50 F 8 means a flat of
width 50 mm & thickness of 8 mm.

33. 18

34. Square hollow section
Hollow section pipe

35. 19

36. STEELAS A STRUCTURAL
MATERIAL

37. 1

38. Advantages of steel design
• Better quality control
• Lighter
• Faster to erect
• Reduced site time - Fast track Construction
• Large column free space and amenable for alteration
• Less material handling at site
• Less percentage of floor area occupied by structural
elements

39. • Has better ductility and hence superior lateral load
behavior; better earthquake resistance
2

40. Disadvantagesof steel design
• Skilled labor is required.
• Higher cost of construction
• Maintenance cost is high.
• Poor fireproofing, as at 1000oF (538oC) 65% & at
1600oF (871oC) 15% of strength remains
• Electricity may be required.

41. 3

42. Chemical composition of steel:
Steel is an alloy which mainly contains iron and carbon. Apart from
the carbon a small percentage of manganese, silicon, phosphorus,
nickel and copper are also added to modify the specific properties of
the steel.
Chemical composition of structural steel (IS 2062-1992 & IS 8500)
Grade C Mn S P Si Carbon
Equivalent
Fe410WA 0.23 1.50 0.050 0.050 0.40 0.42
Fe410WB 0.22 1.50 0.045 0.045 0.40 0.41
Fe410WC 0.20 1.50 0.040 0.040 0.40 0.39
Fe 440 0.20 1.30 0.05(0.04) 0.05(0.04) 0.45 0.40
Fe 490 0.20 1.50 0.05(0.04) 0.05(0.04) 0.45 0.42
Fe 590 0.22 1.80 0.045(0.04) 0.045(0.04) 0.45 0.48

43. Notes:
1. Carbon Equivalent = (C+Mn)/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
2. The terms in the bracket denotes themaximum limitfor the flat products. 4

44. Types of structural steel:
Different structural steel can be produced based on the
necessity by changing slightly the chemical composition and
manufacturing process.
1. Carbon steel: In this type of structural steel carbon and
manganese are used as extra elements.
2. High Strength Carbon Steel: By increasing the carbon
content this type of steel can be manufactured which
basically produces steel with comparatively higher
strength but less ductility.
3. Stainless Steel: In this type of steel mainly foreign
material like nickel and chromium are used along with

45. small percentage of carbon.
5

46. Properties of structural steel
The important mechanical properties of steel are:
ultimate strength, yield stress, ductility,
weldabilty, toughness, corrosion resistance and machinability.
The last four properties are important for durability of material
and often associated with fabrication of steel members.
The mechanical properties of steel largely depend on its
 Chemical composition
 Heat treatment
 Stress history
 Rolling methods

47.  Rolling thickness
6

48. Structural Steel
The steel used for structural works shall confirm to IS 2062 :
2011 (Hot Rolled Medium and High Tensile Structural Steel).
Most Commonly used grade is Fe 410.
Followings are few physical properties of structural steel (As
per clause 2.2.4.1 of IS 800 : 2007):
 Unit mass of steel, ρ = 7850 kg/m3
 Modulus of elasticity, E = 2.0 × 105 N/mm2
 Poisson’s ratio, µ = 0.3
 Modulus of rigidity, G = 0.769 × 105 N/mm2
 Co-efficient of thermal expansion, α= 12 × 10-6 /oc

49. Mechanical properties:
Following are the most important mechanical properties that are
frequently used in design of steel structures.
Yield stress, fy
Ultimate stress, fu
Minimum percentage elongation
These properties can be obtained by performing tensile tests of the steel
sample.
Mechanical propertiesof structural steel products (Table 1 of IS 800 : 2007)
Grade of
Steel
YieldStress (MPa) UltimateTensile
Stress (MPa)
Elongation
Percentage
t<20 t = 20 to 40 t>40
Fe 410 250 240 230 410 23
Fe 440 300 290 280 440 22

50. Fe 490 350 330 320 490 22
Fe 540 410 390 380 540 20
8

51. Some other important mechanical properties of steel
(i) Ductility: It is defined as
the property of a material by
virtue of which it undergoes
large inelastic i.e. permanent
deformation without loss of
strength under the
application of tensile load.
(ii) Hardness: It is one of the mechanical properties of steel
by virtue of which it offers resistance to the indentation and
scratching. The hardness of steel is measured by
 Brinell hardness test
 Vickers hardness test

52.  Rockwell hardness test
9

53. (iii) Toughness: It is one of the mechanical
properties of steel by virtue of which it offers
resistance to fracture under the action of
impact loading.
Toughness = The ability to absorb energy up
to fracture.
 Toughness is generally measured by the area
under the stress-strain curve.
(iv) Fatigue: It is defined as the damage caused by the repeated
fluctuation of stresses which leads to the progressive cracking of the
structural element.
Damage and failure of the material under the action of cyclic
loading.
(v) Resistance against corrosion:
In the presence of moist air corrosion of steel is an extremely important
aspect.

54. To avoid corrosion paint or metallic coating may be used
10

55. Few important terms associated with structural steel:
(a) Residual Stress:
Residual stresses are defined as the stresses which are locked into a
component or assembly of parts. At the time of rolling of steel
sections, fabrication of steel members, they are subjected to very
high temperature and after that they are allowed to cool which is
basically an uneven process. Due to this uneven heating and cooling,
residual stress in the structural member is generated.
(b) Stress Concentration:
Stress concentration indicates a highly localized state of stress at a
particular location of a member. Generally, if there exists an abrupt
change in the shape of the member like in the vicinity of notch or
holes, the stress generated at that location is several times greater
than the stress that would generate without that sudden change in
geometry.

56. 11

57. E
Cʹ
F
B
C D
A
Stress-strain curve for mild steel
Stress-Strain diagram for steel specimen is generally plotted by
performing tensile test, in which a specimen having gauge length
L0 and initial cross sectional area A0 is taken.
fu
fy
O
Strain, ɛ
Stress,
f

58. 12

59. Part OA- In this region the stress is proportional to strain, and is called the
limit of proportionality.
Part AB- After reaching ‘A’, change in strain is rapid compared to that of
stress but still the material behaves elastically up to elastic limit ‘B’.
Cʹ - represents the upper yield point
C - represents the lower yield point.
Part CD- Beyond yield point the material starts flowing plastically without
any significant increase in the stress and material undergoes large
deformation.
Part DE- After reaching point ‘D’, the strain hardening in the material begins
which necessitates requirement of higher load to continue deformation. This
phenomenon is called ‘strain hardening’.
E represents the ultimate stress fu.
Part EF- When the stress reaches point ‘E’ that is the stress corresponding to
the ultimate stress, the necking in material begins.

60. F - represents breaking stress – the stress corresponding to the breaking load.
13

61. LIMIT STATE DESIGN

62. DESIGN PHILOSOPHIES

63. Safety at ultimate load and serviceability at working load

64. Working Stress Method:
Safety is ensured by limiting the stress of the material. The material is
assumed to behave in linear elastic manner. In this approach the stress-strain
behaviour is considered to be linear.
Permissible stress < (Yield stress / Factor of safety)
Details at: IS 800 – 1984.
Permissible stress in steel structural members
Types of stress Notation Permissible
stress (Mpa)
Factor of
safety
Axial tension σat 0.6fy
1.67
Axial compression σac 0.6fy 1.67
Bending tension σbt 0.66fy 1.515

65. Bending compression σbc 0.66fy 1.515
Average shear stress τva 0.4fy 2.5
Bearing stress σp 0.75fy 1.33

66. Working Load×Load Factor
USM: It is also referred to Plastic Design Method. In this case
the limit state is attained when the members reach plastic
moment strength Mp and the structure is attained into a
mechanism. The safety measure of the structure is taken care of
by an appropriate choice of load factor. It is multiplied to the
working load and it is checked w.r.t to the ultimate load
corresponding to the member.
∑ ≤Ultimate Load
LSM: In limit state design method, the structure is designed in
such a way that it can safely withstand all kind of loads that
may act on the structure under consideration in its entire design
life. In this approach, the science of reliability based design was
developed with the objective of providing a rational solution to

67. the problem of adequate safety. Uncertainty is reflected in
loading and material strength.

68. Limit State of Strength
Factors
Governing
Ultimate
Strength
Stability Fatigue Plastic Collapse
Stability Against
Overturning
Sway Stability

69. Limit State of Strength:
These are associated with the failure of the structure under the action
of worst possible combination of loads along with proper partial
safety factor that may lead to loss of life and property. As provided
in IS 800: 2007, Limit state of strength includes –
• Loss of equilibrium of the structure as a whole or in part.
• Loss of stability of the structure.
• Failure due to excess deformation or rupture.
• Fracture due to fatigue.
• Brittle fracture.

70. Check for
Serviceability
Limit States
Deflection
limit
Vibration
limit
Durability
consideration
Fire
Resistance
Limit State Serviceability

71. Limit State of Serviceability:
These are associated with the discomfort faced by the user while
using the structure.
• Excess deflection or deformation of the structure.
• Excess vibration of the structure causing discomfort to the
commuters.
• Repairable damage or crack generated due to fatigue.
• Corrosion and durability

72. Partial Safety Factor for Load
(Clause 5.3.3, Table 4, IS 800: 2007)
𝑄𝑑 = ∑ 𝛾𝑓𝑘𝑄𝑐𝑘
𝑘
Where, 𝛾𝑓 = the partial safety factor for kth load or load effect, 𝑄𝑐
= Characteristic load or load effect, 𝑄𝑑 = Design load or load
effect.
Note
Characteristic values (loads/stresses) are defined as the values
that are not expected to be exceeded within the life of the
structure with more than 5% probability.
Generally partial factor of safety considered is in all cases higher

73. than unity. Whereas for serviceability limit states unit factor of
safety is considered as it is checked under the action of service
load for structure.

74. Partial Safety Factor for Loads, 𝜸𝒇 (Table 4, IS 800: 2007)
Combinatio
ns
Limit State of Strength Limit State of Serviceability
DL LL WL/
EL
AL DL LL WL/
EL
Leadin
g
Accompa
nying
Leading Accomp
anying
DL+LL+CL 1.5 1.5 1.05 - - 1.0 1.0 1.0 -
DL+LL+CL
+WL/EL
1.2 1.2 1.05 0.6 - 1.0 0.8 0.8 0.8
1.2 1.2 0.53 1.2 -
DL+WL/EL 1.5
(0.9)
- - 1.5 - 1.0 - - 1.0
DL+ER 1.2
(0.9)
1.2 - - - - - - -
DL+LL+AL 1.0 0.35 0.35 - 1.0 - - - -

75. Notes:
(i) DL=dead load, LL=imposed (live) load, CL=crane load, WL=wind load, EL=earthquake
load, AL=accidental load.
(ii) During simultaneous action of different live loads one which has greater effect on the
member under consideration is considered as the leading live load.
(iii)Value in the bracket should be considered when dead load contributes to the stability
against overturning or it causes reduction in stress due to other loads.

76. Partial Safety Factor for Material
Partial safety factor for material
𝑆𝑑 = 𝑆𝑢/𝛾𝑚
Where, 𝛾𝑚 = Partial safety factor for material as given in Table 1.5.
𝑆𝑢 = Ultimate strength of the material, 𝑆𝑑 = Design strength of the
material.
Generally, a factor of unity (one) or less is applied to the
resistances of the material.

77. Partial safety factor for material, 𝜸𝒎 (Table 5, IS 800: 2007)
Definition Partial Safety Factor
Resistance governed by yielding, 𝛾𝑚0 1.10
Resistance of member to buckling, 𝛾𝑚0 1.10
Resistance governed by ultimate stress,
𝛾𝑚1
1.25
Resistance of connection Shop
Fabrication
Field
Fabrication
(a) Bolts, friction type, 𝛾𝑚𝑓 1.25 1.25
(b) Bolts, bearing type, 𝛾𝑚𝑏 1.25 1.25
(c) Rivets, 𝛾𝑚𝑟 1.25 1.25
(d) Welds, 𝛾𝑚𝑤 1.25 1.50

78. Deflection Limits (Table 6, IS 800: 2007)
Type of
Building
Deflection Design
Load
Member Supporting Maximum
Deflection
Industrial
Buildings
Vertical
LL/WL Purlins and
girts
Elastic Cladding Span/150
Brittle Cladding Span/180
LL Simple span Elastic Cladding Span/240
Brittle Cladding Span/300
LL Cantilever
span
Elastic Cladding Span/120
Brittle Cladding Span/150
LL/WL Rafter
supporting
Profiled Metal sheeting Span/180
Plastered sheeting Span/240
CL(manual operation) Gantry Crane Span/500
CL (electric operation up to 50t) Gantry Crane Span/750
CL (electric operation over 50t) Gantry Crane Span/1000
Lateral
No cranes Column Elastic Cladding Height/150
Brittle Cladding Height/240
Crane + wind Gantry Crane(absolute) Span/400

79. (lateral) Relative displacement
between rails supporting
crane
10mm
Crane + wind Column/fra
me
Gantry(Elastic cladding,
pendant operated)
Height/200
Gantry(Brittle cladding, cab
operated)
Height/400

80. Deflection Limits (Table 6, IS 800: 2007)
Type ofBuilding Deflection Design
Load
Member Supporting Maximum
Deflection
Other
Buildings
Vertical
LL Floor & Roof Elements not
susceptible to
cracking
Span/300
Elements
susceptible to
cracking
Span/360
LL Cantilever Elements not
susceptible to
cracking
Span/150
Elements
susceptible to
cracking
Span/180
Lateral
WL Building Elastic cladding Height/300
Brittle cladding Height/500

81. WL Inter storydrift - Story
height/300

82. Class 1
Plastic
Classification of Cross
Section
Class 2
Compact
Class 3
Semi-Compact
Cross Sectional Classification (Clause 3.7, Table 2)

83. Load and Load Combinations
 Dead loads – [IS:875 (Part-1)]
 Imposed loads (i.e. Live loads, Crane loads etc) – [IS:875 (Part 2)]
 Wind loads – [IS:875 (Part-3)]
 Snow loads - [IS:875 (Part-4)]
 Temperature, Hydrostatic, Soil pressure, Fatigue, Accidental,
Impact, Explosions etc and load combinations [IS:875 (Part-5)]
 Earthquake load – [IS:1893-2002 (Part-1)]
 Erection loads – [IS:800-2007 Cl. 3.3]
 Other secondary effects such as temperature change, differential
settlement, eccentric connections etc.

84.  In IS:800-2007 (Cl. 5.3.1) the loads/actions acting on a structural
system has been classified in three groups, these are as follows:
 Permanent actions (Qp) – Action due to self-weight of the structural
components, basically the dead loads.
 Variable actions (Qv) – Action due to loads at construction and
service stage such as all type of imposed loads, wind and earthquake
loads etc.
 Accidental actions (Qa) – Action due to accidental loads acting on
the structure such as due to explosion, due to sudden impact etc.
 While designing the steel structure following load combination
must be considered along with partial safety factors
• Dead loads + Imposed loads
 Dead loads + Imposed loads + Wind / Earthquake loads

85.  Dead loads + Wind / Earthquake loads
 Dead loads + Erection loads

86. Wind Load Calculation
Cl. 5.3, IS 875 (Part 3) 1987
The design wind speed (m/s) at any height z is
𝑉𝑧= 𝑘1𝑘2𝑘3𝑉𝑏
Where, 𝑉𝑏 = Basic wind speed (Figure 1)
𝑘1 = Probability factor (risk coefficient)
(Table 1)
𝑘2 = Terrain, height and structure size
factor (Table 2)
Basic
wind
speed, m/s
Zone
55 I
50 II
47 III
44 IV
39 V
33 VI

87. 𝑘3 = Topography factor (Clause 5.3.3 )

88. 𝑧
Design Wind Pressure
(cl. 5.4; IS 875 part 3)
Design wind pressure at any height above mean ground level
is obtained by
𝑝𝑧 = 0.6𝑉2
The wind pressure at any height of a structure
depends on following.
Velocity and density of the air
Height above ground level
Shape and aspect ratio of the building
Topography of the surrounding ground surface
Angle of wind attack

89. Solidity ratio or openings in the structure

90. Design Wind Force:
1. The total wind load for a building as a whole is given by
𝐹 = 𝐶𝑓𝐴𝑒𝑝𝑧 [cl. 6.3 of IS 875 part-3 ]
Where, 𝐶𝑓 =Force coefficient of the building
𝐴𝑒 = Effective frontal area
𝑝𝑧 = design wind pressure
2. Wind force on roof and walls is given by
𝐹 = 𝐴𝑝𝑧 [cl. 6.2.1 of IS 875 part-3]
Where, 𝐶𝑝𝑒 = External pressure coefficient (cl. 6.2.2 of IS 875 part-3)
𝐶𝑝𝑖 = Internal pressure coefficient (cl. 6.2.3 of IS 875 part-3)
𝐶𝑝𝑒 − 𝐶𝑝𝑖

91. A = Surface area of structural element

92. INTRODUCTION TO
CONNECTIONS

93. 1

94. Fabrication of structures between following
members:
• Beam & column
• Beam & beam
• Beam & cross beam
• Column & column
• Column & brackets
• Column & caps
• Base plate of trusses
• Truss member connections through gussets
• Purlins & rafter
• Wind braces and columns

95. • Rails & columns
2

96. • Stiffenersin plate girders
• Diaphragms in plate girders
• Flange and web connections in plate girders
• Stiffenerplates in column joints
Methods of Fabrications:
Rivet Joints
Bolt Joints
Weld Joints
The combinations of two or three of the above

97. 3

98. Requirements of good connection
1. It should be rigid enough to avoid fluctuating
stresses which may cause fatigue failure.
2. It should be such that there is the least possible
weakening of the parts to be joined.
3. It should be such that it can be easily installed,
inspected, & maintained.

99. 4

100. RIVET CONNECTION
Rivet Head
Head
Shank

101. Diameter
Nominal Diameter
5

102. Advantages of Riveted connections
 Ease of riveting process.
 Rivet connection is permanent in nature
 Cheaper fabrication cost.
 Low maintenance cost.
 Dissimilar metals can also be joined, even non-metallic joints
are possible with riveted joints.
 Rivet connection is possible without electricity in remote area

103. Disadvantages of Rivet Connection:
(i) Necessity of pre-heating the rivets prior to driving
(ii) High level of noise
(iii)Skilled work necessary for inspection of connection
(iv)Cost involved in careful inspection and removal of poorly
installed rivets
(v)Labor cost is high

104. 7

105. Rivet
Power driven riveting
or Hot rivet
Hand driven riveting
or Cold rivet
Power driven shop
rivet(PDS)
Power driven
field rivet(PDF)
Hand driven
shop rivet(HDS)
Hand driven field
rivet(HDF)

106. 8

107. Commonly used rivet head
1.6d
0.7d
2d
0.25d
Length Length
Snap Head
d
Flat head
d

108. 9

109. Assumption:
1. Friction between the plates is neglected.
2. The shear stress is uniform on the cross section of
the rivet.
3. The distribution of direct stress on the portion of the
plates between the rivet holes is uniform.
4. Rivets in group subjected to direct loads share the
load equally.
5. Bending stress in the rivet is neglected.
6. Rivets fill completely the holes in which they are
driven
7. Bearing stress distribution is uniform and contact

110. area is d × t
10

111. BOLT CONNECTION
Clause 2.4: Bolts, nuts
and washers shall
conform as
appropriate to:
IS 1363-1967, IS 1364-
1967, IS 1367-1967, IS
3640-1967, IS 3757-
1972, IS 6623-1972 and
IS 6639-1972

112. Advantages:
• Less Manpower
• High strength bolts are much stronger than
rivet. Hence, bolted connections need less
fasteners than rivet joints
• Bolting operation is much faster
• Bolting operation is very silent in contrast to
hammering noise in riveting
• Bolting is a cold process; No risk of fire
• Bolt can be removed, replaced or retightened
easily in the event of faulty bolting or
damaged bolts due to accidents/hazards

113. Disadvantages:
• Bolted connections have lesser strength in
axial tension as the net area at the root of
the threads is less
• Under vibratory loads, the strength is reduced
if the connections get loosened
• Unfinished bolts have lesser strength because
of non uniform diameter
• Architectural look

114. TYPES OF BOLT
• According to material and strength
(i) Ordinary structural bolt
(ii) High strength steel bolt
• According to Type of Shank
(i) Unfinished or black bolt
(ii) Turned bolt
(iii) High strength friction grip (HSFG) bolt
• According to pitch and fit of thread
(i) Standard pitch bolt
(ii) Fine pitch bolt
(iii) Coarse pitch bolt
• According to shape of head and nut
(i) Square bolt

115. (ii) Hexagonal bolt

117. Terminology
Pitch, p  Pitch is the centre to centre distance of adjacent rivets or bolt holes
measured in the direction of stress.
Minimum pitch: 2.5 d (clause 10.2.2)

118. To prevent bearing failure between two bolts
Sufficient space to tighten bolts
16

119. Terminology
Maximum pitch: Desirable to place boltssufficiently closed (clause 10.2.3)
(1) To reduce length of connectionand gusset plate
(2) To have uniform stress
(Distance between two consecutive bolts) < 16 t or 200 mm in tension
< 12 t or 200 mm in compression
(Distance between two adjacent bolts) < 32 t or 300 mm
Gauge, g  A row of rivets which is parallel to the direction of stress is called
gauge line. The normal distance between two adjacent gauge lines is called
gauge.
Edge distance, e  The distance between the edge of a member or cover plate
from the centre of the nearest rivet/bolt hole.

120. Minimum edge distance for rivet: 1.5 d
17

121. Nominal diameter, d It is the diameter of the shank of the
rivet. For bolts the diameter of the unthreaded portion of the
shank is called its nominal diameter.
Gross diameter, D The diameter of the rivet hole or bolt
hole is called its gross diameter.
For rivet:
As per clause 3.6.1.1 of IS 800:1984
D = d + 1.5 mm for d < 25mm
= d + 2 mm for d 25mm

122. 18

123. For Bolt:
Minimum and maximum edge distance and end distance are given in
clause 10.2.4.2 and 10.2.4.3
The minimum edge/end distances > 1.7 times the hole diameter
(In case of sheared or hand-flame cut edges)
> 1.5 times the hole diameter
(In case of rolled, machine-flame cut, sawn and planed edges.)
The maximum edge distance < 12tε where ε = (250/fy)1/2
(t is the thickness of the thinner plate)

124. Bolt holes:
Bolt holes are required to facilitate the insertion of bolts to make
connection between steel members. Bolt holes are usually made
larger than the nominal diameter of bolt to smooth the progress of
erection and accommodate minor discrepancies.
Bolt hole = bolt diameter + clearances of hole (Clause 10.2.1, Table 19)
Diameter, d Standard clearance Over size Short slot Long short
12-14 1 3 4 2.5 d
16-22 2 4 6 2.5 d
24 2 6 8 2.5 d
>24 3 8 10 2.5 d

125. INTRODUCTION TO
BOLT CONNECTIONS

126. 1

127. TYPES OF JOINTS
(i)Depending upon arrangement of bolts& plates
(ii) Depending upon mode of load transmission
(iii)Depending upon nature and location of load

128. 2

129. TYPES OF BOLT JOINTS
(i) Depending upon arrangement of bolts and plates
Lap Joint
Butt Joint
Single line bolting
Chain bolting
Staggered or zig-zag bolting
Single bolting
Chain bolting
Staggered or zig-zag bolting

130. 3

131. Bolting pattern
Chain bolting
Zig-Zag bolting
Diamond bolting

132. (i) Depending upon arrangement of bolts and plates
Single bolted Lap Joint:
Triple bolted lap joint:
Single bolted single cover butt joint:
Single bolted double cover butt joint
Double bolted double cover butt joint

133. 5

134. TYPES OF BOLT JOINTS
(ii) Depending upon the mode of load transmission
(a)Single shear
(b) Double shear
(c) Multiple shear

135. 6

136. (ii) Depending upon the mode of load transmission
(a)Single shear
(b)Double shear
(c)Multiple shear

137. 7

138. TYPES OF BOLT JOINTS
(iii) Depending upon nature and location of load
(a) Direct shear connection
(b)Eccentric connection
(c) Pure moment connection
(d) Moment shear connection

139. 8

140. (a) Direct shear connection

141. 9

142. (b) Eccentric connection

143. 10

144. (c) Pure moment connection

145. 11

146. (d) Moment shear connection

147. 12

148. The following are the failure modes of a bolted joint:
•Shear failure of the bolt
•Bearing failure of the bolt
•Tensile failure of bolt
•Shear failure of the plate
•Bearing failure of the plate
•Tensile failure of plate

149. Shear Failure of Bolt
(a) Single shear
(b) Double shear

150. 14

151. Things to remember for bolted connections:
•Stress concentration results in a considerable decrement
in the tensile strength.
•Loose fit of the joint can reduce the stiffness which may
result in excessive deflections.
•Vibrations can cause loosening of nuts which can
jeopardize the safety of structure.

152. • The length of joint should be as small as possible to
save material on cover plates and gusset plates.
• The center line of all the members meeting at a joint
should coincide at one point only. Otherwise the joint will
twist out of position.
• The number of bolts should be increased gradually
towards the joint for uniform stress distribution in bolts .
Criteria for designing bolted joints with
axially loaded members

153. • The arrangement should satisfy the pitch, gauge and edge
distance requirements.
• The strength of joint reduces due to the bolt holes. The
reduction in area due to bolt holes can be minimized by
arranging in a zig-zag form.
Criteria for designing bolted joints with
axially loaded members

154. B
D E
C
A