1. SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION)
SLUDGE DISPOSAL
SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35
(AN AUTONOMOUS INSTITUTION)
TYPES OF CONNECTIONS
CE312 DESIGN OF STEEL STRUCTURES
PRESENTED BY,
O.R.KAVITHA
ASSOCIATE PROFESSOR
DEPT. OF CIVIL ENGINEERING
SNS COLLEGE OF TECHNOLOGY
9/15/2018
CE 312 / DSS/ Unit I

2. CE 312 / DSS/ Unit I
9/15/2018
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.

3. CE 312 / DSS/ Unit I
9/15/2018
Types of Connectors
Components which make up the complete structure are fastened together by means of:
RIVETS (older version)
BOLTS (newer version)
WELDS

4. Steel rivets are always heated before driving
CE 312 / DSS/ Unit I
9/15/2018
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

5. CE 312 / DSS/ Unit I
9/15/2018
Rivets:
Rivets are generally made from steel conforming to ASTM A502 and comes in 2 grades:
Grade 1(carbon steel)
Grade 2 (carbon-manganese steel)
Round Head Rivet
Countersunk Rivet

6. Grip – It is the distance between the undersides of the two heads
Terms used in Rivets
CE 312 / DSS/ Unit I
9/15/2018
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

7. Different shapes of heads
CE 312 / DSS/ Unit I
9/15/2018
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.
Different shapes of heads
A rivet is made up of a round ductile steel bar piece called shank, with a head at one end.

8. CE 312 / DSS/ Unit I
9/15/2018

9. Patterns of Riveted joints
CE 312 / DSS/ Unit I
9/15/2018
Patterns of Riveted joints

10. Rivets: Riveting processes
CE 312 / DSS/ Unit I
9/15/2018
Rivets: Riveting processes
Rivet Heating Oven
Rivet Heater
Rivet Heating Oven

11. Earlier Riveting Gun Modern Riveting Gun CE 312 / DSS/ Unit I
9/15/2018
Earlier Riveting Gun
Modern Riveting Gun

12. Characteristics of riveted connections
CE 312 / DSS/ Unit I
9/15/2018
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.

13. Disadvantages Riveting required a staff of 4 to 5 experienced riveters
CE 312 / DSS/ Unit I
9/15/2018
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

14. CE 312 / DSS/ Unit I
9/15/2018

15. CE 312 / DSS/ Unit I
9/15/2018
BOLTS
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

16. CE 312 / DSS/ Unit I
Bolt Assembly
9/15/2018

17. CE 312 / DSS/ Unit I
9/15/2018

18. b)High strength bolt (A325,A449,A490).
CE 312 / DSS/ Unit I
9/15/2018
Bolts: Two common types of bolts are
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.

19. CE 312 / DSS/ Unit I
9/15/2018
Unfinished bolts
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.

20. These are made from medium carbon heat treated steel and alloy steel.
CE 312 / DSS/ Unit I
9/15/2018
High strength 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

21. Tightening procedures
CE 312 / DSS/ Unit I
9/15/2018
Tightening procedures
Turn of the nut method
Calibrated-wrench tightening
Installation of alternate design bolts
Direct-tension-indicator tightening

22. Types of bolted joints ( 2Marks Q& A)
CE 312 / DSS/ Unit I
9/15/2018
Types of bolted joints ( 2Marks Q& A)
LAP JOINT
Two members to be connected are overlapped and connected together is called lap joint

23. CE 312 / DSS/ Unit I
9/15/2018

24. Plates provided on both side is called double cover butt joint.
CE 312 / DSS/ Unit I
9/15/2018
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.

25. Load transfer Mechanism
CE 312 / DSS/ Unit I
9/15/2018
Load transfer Mechanism
Depending on types of bolts the load transfer from ne connected part to
another may shear or bearing
Slip-Critical connections
The clamping force applied to the bolt brings the two members close enough so
that appreciable friction is produced between them which is then responsible for
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 bolt or
threaded portion.

26. Type of connection Failures
CE 312 / DSS/ Unit I
9/15/2018
Type of connection Failures
Shearing Failure of Bolts.
Bearing Failure of plate.
Tearing failure at edge of plate.

27. Type of connection Failures
Shearing failure of bolts

28. Type of connection Failures
Bearing Failure of Plate

29. Tearing Failure at edge of Plate
Type of connection Failures
Tearing Failure at edge of Plate
Shearing Failure edge of plate
Transverse Tension Failure

30. Type of connection Failures
CE 312 / DSS/ Unit I
9/15/2018
Type of connection Failures
Failures

31. Eccentricity of Applied Force
Type of connection Failures
Eccentricity of Applied Force
Plates of lap joint tends to bend.
Bending produces non uniform bearing of the fastener on the plates

32. Tearing Failure at edge of Plate
Type of connection Failures
Tearing Failure at edge of Plate
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.

33. Important terminologies
CE 312 / DSS/ Unit I
9/15/2018
Important terminologies
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.
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.

34. 1.3.33 Edge Distance — Distance from the centre of a
CE 312 / DSS/ Unit I
9/15/2018
Pitch — The centre-to-centre distance between individual fasteners in a line, in the direction of load/stress.
End Distance — Distance from the centre of a fastener hole to the edge of an element measured parallel to the direction of load transfer.
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 ( pg 73)
Edge and End Distances ( pg 74)

35. CE 312 / DSS/ Unit I
9/15/2018
Thank you