1. CONNECTIONS IN STEEL STRUCTURES
SEMINAR ON
CONNECTIONS IN STEEL STRUCTURES

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 fastners,so that it shows a single composite unit.

4. Components Of A Connections
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 Included - Decreased stregth.
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 stregth.

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 Disadvantages 1. The bolting operation is very silent
2. Bolting is a cold process hence there is no risk of fire
3. Bolting operation is more quicker than riveting.
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
whose components are joined together primarily by welds.
Welding Notations were developed by
American Welding Society (AWS).

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 labors.
Efficiency is 100% as compared to rivets ( %)
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. Field Bolted Moment Connection
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 leveling.
Anchor bolts should be
provided to stabilize the
column during erection
or to prevent uplift.

44. R Usually cost of fabrication and erection
constitute as high as 50% of the total cost of
steel structures, per tones of material used