This presentation gives complete overview of connections used in steel structures.

1. CONNECTIONS IN STEEL
STRUCTURES
Narayan R Chandak
Professor Dept of
Civil Engg.

2. Introduction
 Connections are structural elements used for joining
different members of a structural steel frame work.
 Steel Structure is an assemblage of different member
such as “BEAMS,COLUMNS” which are connected to
one other, usually at member ends fasteners, so that it
shows a single composite unit.

4. Components of a Connections
Rivets
Bolts
 Weld

5. Connecting Plates
 Connecting Angles

6. Classification of Connections
 On the Basis of Connecting Medium.
 According to the type of internal forces.
 According to the type of structural Elements
 According to the type of members joining

7. On the Basis of Connecting Medium
Riveted Connections
Bolted Connections

8. Welded Connections
 Bolted-Welded Connections

9. Riveted Connections
 Used for very long time.
 Made up of:
• Round Ductile steel bar called shank
• A head at one end
The length of the rivet should sufficient to form the second head.
 Design - very similar to bearing type of bolted connection.

10. Installation
 Heating of the rivet
 Inserting it to an oversize hole pressure to the
head.
 Squeezing the plain End by Pneumatic driver
Round head.
 On Cooling Reduces in
Length–Clamping Force

12. Riveting is no longer used…
 The introduction of high strength structural bolts.
 The labour costs associated with large riveting crews
 The cost involved in careful inspection and removal of poorly
installed rivets.
 The high level of noise associated with driving rivets.

13. Bolted Connections
 Fastened Together primarily by Bolts.
 Bolts may be loaded in:
Tension
Shear
Both Tension & Shear
 Threads of bolts under shear force:
Excluded - Increased strength
Included - Decreased strength.

14. Types of Bolts
 Bearing type bolts
 High strength friction grip bolts (HSFG)

15.  The most common type is bearing bolts in clearance holes, often referred to as
1. Black Bolts
 Ordinary, unfinished, rough, or common bolts.
 Least Expensive
 Primarily - Light structures under static load such as small trusses, purlins etc.

16. 2. Turned Bolts
 Similar to unfinished bolts.
 Shanks - Hexagonal Rods
 Primarily - Light structures under static load such as small trusses, purlins etc.
 Expensive – Limited use – Structures with no Slippage Connections

17. 3. Ribbed Bolts
• Round head similar to Rivets.
• Raised ribs parallel to the shank.
• Actual Diameter - slightly Larger than the hole
• Tightly fit into the hole.
• Popular - Economical in Material & Installation

18. High Strength Friction Grip (HSFG)
 Uses when bearing type bolts slips under shear.
 High strength bolts (8G or 10K grade) Pre-tensioned
against the plates to be bolted together so that contact
pressure developed between the plates being joined
 Prevents relative slip when extra shear is applied.
 Higher Shear Resistance.

19. Advantages
1. The bolting operation is very silent
2. Bolting is a cold process hence there is no risk of fire
2. Bolting operation is more quicker than riveting.
3. Less man power is required in making the connections.
Disadvantages
1. If subjected to vibratory loads, results in reduction in strength, get loosened.
2. Unfinished bolts have lesser strength because of non uniform diameter.

20. Welded Connections
 Components are joined together primarily by welds.

21. Types of Weld
Groove ( More reliable than others)
Fillet (Mostly used, Weaker than groove
and others)
Plug (expensive – poor transmission of
tensile forces)
Slot (expensive - poor transmission of
tensile forces)
Plug and Slot welds – stitch different
parts of members together.

22. Positions of the welds
 Horizontal
 Vertical
 Overhead
 Flat

23. Advantages
 Economical – Cost of materials and labours.
 Efficiency is 100% as compared to rivets (75- 90%).
 Fabrication of Complex Structures – Easy – like
Circular Steel pipes.
 Provides Rigid Joints – Modern practice is of Rigid Joints.

24. Disadvantage
 No provision for expansion or contraction therefore greater
chances of cracking.
 Uneven heating and cooling - member may distort - may result
in additional stresses.
 Inspection is difficult and more costlier than rivets.

25. Bolted- Welded Connections
 Most connections are Shop Welded and Field Bolted types.
 More Cost Effective
 Better Strength &
Ductility characteristics –Fully welded.

26. According to the type of internal
 Shear (semi rigid, simple) connections
 Moment (rigid) connections

27. Shear (semi rigid, simple) connections
 Allows the beam end to rotate without a significant restraint.
 Transfers shear out of beam
 Most Common Types:
Double clip
Shear End Plate
Fin Plate

28. Moment (rigid) connections
 Designed to resist both Moment and Shear.
 Often referred - rigid or fully restrained connections
• Provide full continuity between the connected members
• Designed to carry the full factored moments.
 Principal Reason - buildings has to resist the
effect of lateral forces such as wind and
earthquake.

29. Bolted splice Moment Connection
Field Bolted Moment Connection

30. According to the type of structural Elements
 Single plate angle Connections
 Double web angle connections
 Top and seated angle connections
 Seated beam connections

31. Single plate angle Connections
Two Step Process
 A plate is welded to secondary section (beam)
 An Angle is welded to Primary Section (column or Beam)
 single shear plate welded to secondary
beam and bolted to Primary beam or column.

32. Double web angle connections
 Two angles welded or shop bolted to the web
of a secondary beam.
 After erection the angles are bolted or site
welded to the primary member (beam or
column).

33. Top and seated angle connections
 Generally used in case of moment connections.
 Two angles are provided at top and bottom of
the beam to resist moment.
 Generally used for lesser moments where
heavy loads are not acting

34. Seated beam connections
 Generally used in case of shear connections.
 A seating angle - at bottom of secondary
beam - shop welded to the primary member.
 Seating angle resists vertical shear coming
from the beam.

35. According to the type of members joining
 Beam to beam connections
 Column to column connections
(column splices)
 Beam to Column Connections
 Column Base Plate Connections

36. Beam to beam connections
Two Types
 Primary Beam to Secondary Beam Connection
 Beam Splice

37. Column to column connections
(column splices)
 Connects column to column.
 Column splice comes under this category.
 Used to connect column sections of different sizes.
 Splices - designed for both moment and shear unless intended to
utilize the splices as internal hinges.

38. Beam to Column Connections
 Connects Beam to column.
 Very Common
 A wide range of different types
are used:
Fin Plates
End Plates
Web or Flange Cleats
Hunched Connections

39. Beams are normally attached using two or more
bolts through the web.
End plate connections
Single plate welded to the end of the beams
Bolted to the column flange or web - two or
bolts pair.
Fin plate connections
Single Plate welded to the Column.
Beams are normally attached using two or more
bolts through the web.

41. Column Base Plate Connections
 Steel plates placed at the bottom of Columns.
 Function - to transmit column loads to the
concrete pedestal.
 The design of a column base plate:
determining the size of the plate.
determining the thickness of the plate

42.  A layer of grout should be placed between the base plate and its
support for the purpose of levelling.
 Anchor bolts should be provided to stabilize the column during
erection or to prevent uplift.

44. Thank you