Every superstructure like bridges, railways, aircraft, sheds, etc. is a combination of steel members. These huge structural members are held together with the help of rivets or bolts.
In the present day, the use of rivets is more common. Rivets are bolts like structures, which are fixed in the pre-drilled holes of the joining members or steel plates. They are made up of ductile materials. Rivets are permanently fixed whereas bolts are temporarily held fast with the help of nut and bolt combination.
The parts of rivet are head, shank and tail. The shank is also known as the grip length.
The installation process of a rivet is as shown in the fig. below –
Types of Rivet Joints
Let’s see the type of joints commonly used in steel structures.
- Lap joint
It is the least efficient joint because the line of action of two forces (P) is not the same. These two forces form a couple which produces additional bending stresses. As per IS 300:2000, the effect of bending stress can be neglected if grip length/shank < 5d. In a lap, joint bolts are subjected to angle shear and bending and the rivets/bolt are in single shear as shown in fig below.
- Single cover butt joint
The line of action of two forces (P) is the same but the connection is not symmetrical to the x-axis. A single cover butt joint is more efficient than lap joint as rivets/bolts are in single shear as shown in fig below.
- Double cover butt joint
The line of action of two forces (P) is the same and symmetric along the x-axis. In the double cover butt, joint rivets/bolt are in double shear as shown in fig below.