TYPES OF CONNECTIONS (STEEL STRUCTURE DESIGN)

PRESENTED BY,
O.R.KAVITHA
ASSOCIATE PROFESSOR
DEPT. OF CIVIL ENGINEERING
SNS COLLEGE OF TECHNOLOGY
06/16/25
CE 312 / DSS/ Unit I
SNS COLLEGE OF TECHNOLOGY, COIMBATORE-
35
(AN AUTONOMOUS INSTITUTION)
CE312 DESIGN OF STEEL STRUCTURES

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*The various elements of steel structure like tension
member, compression member and flexural member are
connected by fasteners or connectors.
*Built-up sections are provided to meet the requirement of
heavy loads &long spans , such connections need to be
connected together to act in union as one unit
*The forces exerted by one element on another are
transferred through these connectors, and it should be
adequate to transmit the forces safely.

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Types of Connectors
*Components which make up the
complete structure are fastened together
by means of:
1.RIVETS (older version)
2.BOLTS (newer version)
3.WELDS

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1. Rivets:
* They are made from rivet bar stock in a machine
which forms one head and shears the rivet to
desired length.
* Steel rivets are always heated before driving
* Most rivets are driven by pressure-type riveters
which complete riveting in one stroke.
Typical Round Head Rivet

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*Rivets:
*Rivets are generally made from steel conforming to
ASTM A502 and comes in 2 grades:
i. Grade 1(carbon steel)
ii. Grade 2 (carbon-manganese steel)
Countersunk Rivet
Round Head Rivet

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Terms used in Rivets
Shank – It is made of the length to extend through
the parts to be connected & with sufficient extra
length for a second head to be made at the other
end.
Grip – It is the distance between the undersides of
the two heads
( shank length inside the connectors).
Nominal diameter – The diameter of the shank

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Types of Rivets
•When rivets are heated before driving is called hot
driven field or hot driven shop rivets.
• When rivets are not heated before driving is cold
driven rivets.
A rivet is made up of a round ductile
steel bar piece called shank, with a
head at one end.
Different shapes of
heads

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Patterns of Riveted joints

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1. Rivets: Riveting processes
Rivet Heating Oven
Rivet Heater
Rivet Heating Oven

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Earlier Riveting Gun Modern Riveting Gun

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Characteristics of riveted connections
• In riveted connections magnitude of clamping is function of
length of rivet and magnitude of shrinkage after the head is
formed.
• Magnitude of slip depends on the extent to which rivet fills the
hole.

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Disadvantages
*Riveting required a staff of 4 to 5 experienced riveters
*Bolt installation is less labor intensive
*Riveting is time consuming operation requiring preheating, driving
and finishing
*Rivet strength is low compared to high strength bolts
*High strength bolts are now economical
*Riveting is still used in some industries and applications such as
aircraft industry

Definition - It may be defined as a metal pin with a head at one
end a shank threaded at the other and to receive a nut.
Advantages – 1. The erection can be speeded up
2. Less skilled persons required
3. The overall cost is cheaper.
Disadvantages-
1.When members subjected to vibrations or shock it may get loose
2. Normally these are of loose fit excepting turned bolts and hence
their strength is reduced.
3. The tensile strength of the bolts is reduced because area
reduction at the root of the thread and due to stress concentration
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Bolt Assembly

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Bolts: Two common types of bolts are
a) Unfinished bolt (A307)
•A307 is known by names unfinished, rough, common,
ordinary and machine.
•They are made of low carbon steel having tensile
strength .
b)High strength bolt (A325,A449,A490).
•A325 is made of medium carbon steel whose tensile
strength decreases with increase in dia.
•High strength bolts can be tightened to large tensions.

• These are called ordinary, common, rough or block bolts.
• Used for light structures subjected to static & secondry
members such as purlins & bracings,roof trusses.
• Size of bolts available- 5 to 36mm and it is designated as M5
to M36.
• In this type of bolted joint the force is transferred through
interlocking & bearing of bolts and the joint is called bearing-
type joint.
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Unfinished bolts

• These are called friction type bolts or non-slip connection or
friction type connection.
• These are made from medium carbon heat treated steel and
alloy steel.
• High strength is achieved by quenching & tempering process.
• In this type of bolted joint the force is transferred through
friction between inter faces formed between the load carrying
elements jointed as figure b.
• Due to this friction slip is eliminated (which is in ordinary
bolt).
• This friction is developed by applying a load normal to the
joint by tightening these bolts to proof load
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Tightening procedures
1.Turn of the nut method
2.Calibrated-wrench tightening
3.Installation of alternate design bolts
4.Direct-tension-indicator tightening

Types of bolted joints ( 2Marks Q& A)
•LAP JOINT
Two members to be connected are overlapped and
connected together is called lap joint
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 LAP JOINT
 Two members to be connected are overlapped and
connected together is called lap joint
BUTT JOINT
 Two members to be connected are placed end to end is
called butt joint.
COVER PLATE
 Additional plates are provided on either one or both
sides called cover plates.Plates provided on one side is
called single cover butt joint.
 Plates provided on both side is called double cover butt
joint.
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Load transfer Mechanism
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Depending on types of bolts the load transfer from ne connected part
another may shear or bearing
Slip-Critical connections
The clamping force applied to the bolt brings the two members close enoug
that appreciable friction is produced between them which is then responsib
resisting the load. The more the clamping force the
more is the friction and strong is the connection but the
clamping force need not to be greater than tensile strength of the bolt.
Bearing type connections
Load is transferred by shearing and bearing on the bolt.
Capacity in shear depends on whether shear plane intersects the body of bo
threaded portion.

Type of connection Failures
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1. Shearing Failure of Bolts.
2. Bearing Failure of plate.
3. Tearing failure at edge of plate.

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1. Shearing failure of bolts

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2. Bearing Failure of Plate

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2. Tearing Failure at edge of Plate
Shearing Failure edge of plate Transverse Tension Failure

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https://unacademy.com/lesson/failure-of-bolted-joints/8GRU2WZY
Failures

 Plates of lap joint tends to bend.
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 Bending produces non uniform bearing of
the fastener on the plates

 Tests showed, failure by tearing through free edge of material will
not occur if Le measured parallel to line of applied force is not
less diameter of bolt multiplied by ratio of bearing stress to
tensile strength of connected part.
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3. Tearing Failure at edge of Plate

 1.3.55 Gauge — The spacing between adjacent parallel
lines of fasteners, transverse to the direction of
load/stress.
 1,3.57 Gusset Plate — The plate to which the members
intersecting at a joint are connected.
 1.3.88 Shear Lag — The in plane shear deformation
effect by which concentrated forces tangential to the
surface of a plate gets distributed over the entire
section perpendicular to the load over a finite length of
the plate along the direction of the load.
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 1.3.72 Pitch — The centre-to-centre distance between
individual fasteners in a line, in the direction of
load/stress.
 1.3.40 End Distance — Distance from the centre of a
fastener hole to the edge of an element measured
parallel to the direction of load transfer.
 1.3.33 Edge Distance — Distance from the centre of a
fastener hole to the nearest edge of an element measured
perpendicular to the direction of load transfer.
Minimum & Maximum pitch (10.2.2 pg 73)
Edge and End Distances (10.2.4 pg 74)
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TYPES OF CONNECTIONS (STEEL STRUCTURE DESIGN)

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