Different types of joints used in steel structure.

In steel structures, various types of joints are used to connect structural members together. These joints are designed to provide stability, strength, and flexibility to the overall structure. Here are some commonly used types of joints in steel structures:

1. Bolted Joints: Bolted joints involve connecting steel members using bolts and nuts. Holes are drilled through the members, and bolts are inserted and tightened to create a connection. Bolted joints offer ease of installation, disassembly, and potential for future modifications or repairs. They can be either permanent or temporary.
2. Welded Joints: Welding is a commonly used method for joining steel members in structural applications. It involves melting the edges of the members and fusing them together to create a strong and permanent connection. Welded joints provide excellent strength and rigidity, but they require skilled labor and specialized equipment. Various types of welding techniques can be used, such as arc welding, MIG welding, TIG welding, and more.
3. Riveted Joints: Riveting was widely used in the past, but it has been largely replaced by bolted and welded joints. However, in some historical or specialized applications, riveted joints may still be found. Rivets are cylindrical metal pins that are inserted through pre-drilled holes in the steel members. They are then hammered or pressed to form a permanent connection. Riveted joints offer high strength but require more time and labor compared to bolted or welded joints.
4. Pinned Joints: Pinned joints allow rotational movement between connected members while preventing translation or sliding. These joints are typically used in truss structures or other systems where flexibility is required. Pinned joints can be achieved by using pins, bolts with shear connections, or other methods that allow rotation.
5. Moment-Resisting Joints: Moment-resisting joints, also known as rigid joints, are designed to transfer bending moments between members, providing continuity and rigidity to the structure. These joints are commonly used in frames subjected to lateral loads, such as wind or seismic forces. Welding is typically employed to create moment-resisting connections.
6. Slip-Critical Joints: Slip-critical joints are used when the connected members are subjected to shear forces or loads that tend to slide the joint surfaces relative to each other. These joints rely on the friction between the surfaces to resist slipping. Bolted connections with high-strength bolts are often used in slip-critical joints, and the bolts are tightened to specific torque values to achieve the required friction.
7. Flange Joints: Flange joints are used to connect steel sections with flanges, such as I-beams, channels, or H-sections. The flanges of the members are brought into contact, and bolts or welds are used to create a connection. Flange joints are commonly employed in the construction of beams, columns, and beam-column connections.

These are some of the key types of joints used in steel structures. The selection of the appropriate joint type depends on factors such as the structural design, load requirements, construction methods, and the desired level of flexibility or rigidity in the structure.