Connections....
Steel structures are formed by connecting available standard section.Connection form an important part of any structure and are designed more conservatively than the individual members.
The connections provided in steel- structures can be classified as follows
(1)- Riveted connection.
(2)- Bolted Connection.
(3)- Welded Connection.
(4)- Pinned Connection.
(1)- Riveted connection.
Riveted connection is old and at this time not in use ,but for rehabilitation of older structure an understanding of its behaviour and design is essential.
A rivet is made up of a round ductile steel bar piece called shank with a head one end.
Shank- A rivet is made up of a round ductile steel bar called shank as shown in fig.
The grip length should not be more than 4d.
Nominal Diameter- The diameter of shank is called the nominal Diameter
Pattern of riveted joint
(1) Chain riveting.
(2) Diamond riveting.
(3)- Staggered Chain riveting.
(4)- Staggered diamond riveting.
Process of riveting
Riveting can be done either hot riveting or cold riveting
Cold riveting
Cold riveting is not adopted for dia greater than 10mm.
Hot riveting
In hot riveting rivet is heated to 500-600°C and is inserted inside the hole in the members to be connected and hammering is done from the opposite side making head on the other side
Riveting can be classified as
Power driven
Hand driven
Shop riveting
Field rivetin
Thus the various type of riveting
Power driven shop riveting
Power driven field riveing
Hand driven shop riveting
Hand driven field riveing
Nominal diameter of rivet (d):
It means the dia of rivet shank or we can say that dia of the cold shank.
Gross diameter of rivet (D):
.The dia of the hole made on the plate should be slightly grater than the dia of rivet
Dia of hole = nominal dia of rivet (d)+1.5 mm ( when d≤ 25mm )
Dia of hole = Nominal dia if rivet (d)+2 mm
(when d> 25mm)
Where d= nominal dia of rivet
Diameter of rivet
The diameter of rivet can be determined by using the following formula.
(1)-Unwins’s formula d=6.05√ t
(2)- French formula d=1.5 t + 4
(3)- German formula d=√(50 t – 2)
Where t = minimum thickness of plate
Assumptions of rivet connection
(1) Friction between the plates is neglected
In case of hot riveting due to shrinkage tendency of rivet gripping takes places between the plates which leads to development of friction between the plates this friction will resist some part of external loading but we dont know exactly how much amount of friction will be resisted.
If we neglect this friction and we will design the rivet for compelete external force then we will be on the safer side.
(2)-Shear stress distribution is assumed uniformed over the cross sections.
(3) Distribution of direct stress on the position of plates between the rivet hole is assumed uniform.
(4)-Rivet in group subjected to direct load shear the load equally.
(5) Bending stress in the rivet is neglected.
Disadvantages of Riveted connection.
(1) Removing poorly installed rivet is costly.
(2) Installation cost is high.
(3) It is associated with high level of noise Pollution.
(4) It needs heating the rivet to red hot
(5) Inspection of connection requires a skilled person.
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