What are the connection methods of steel structures?

★ Welding

Advantages: strong adaptability to geometric shapes; Simple structure; Without weakening the section, automatic operation can be realized; The tightness of the connection is good, and the structural stiffness is large

Disadvantages: high material requirements; In the heat affected zone, it is easy to cause local material change; Welding residual stress and residual deformation reduce the bearing capacity of the member. The welded structure is sensitive to cracks. The problem of low temperature and brittleness is more prominent

★ Riveting

Advantages: reliable force transmission, good toughness and plasticity, easy to check quality, good anti-dynamic load performance

Disadvantages: complex structure, waste steel labor

★ Ordinary bolt connection

Advantages: convenient loading and unloading, simple equipment

Disadvantages: low precision bolt should not be cut; When the precision of bolts is high, the processing and installation are complicated and the price is high

★ High strength bolted connection

Advantages: friction shear deformation is small, good elastic properties, especially suitable for the structure of dynamic load. The bearing capacity of the pressure type is higher than that of the friction type and the connection is compact

Disadvantages: friction surface treatment, installation process is slightly complex, the cost is slightly higher; The shear deformation of the bearing type connection is large, and it should not be used in the structure under dynamic load.

Second, the characteristics of welding connections and welding structures

1, the advantages and disadvantages of welding connections

Compared with rivets and bolts, welded connections have the following advantages:

1) No need to punch, save labor and time;

2) Any shape of the component can be directly connected, the connection structure is convenient;

3) Good air tightness and water tightness, large structural stiffness and good integrity.

Cons:

1) There is a heat affected zone near the welding, and the material becomes brittle;

2) The residual stress of welding makes the structure prone to brittle damage, and the residual deformation changes the shape and size of the structure;

3) Once the welding crack occurs, it is easy to expand.

2. Common welding defects:

Cracks, pores, incomplete welding, slag inclusion, edge biting, burning through, pits, collapse, incomplete welding.

3, welding quality inspection:

Weld quality inspection methods: appearance inspection, ultrasonic inspection, X-ray inspection.

Weld quality classification: the first grade weld should pass the appearance inspection, ultrasonic inspection and X-ray inspection; Secondary welds shall be qualified by appearance inspection and ultrasonic inspection; The third grade weld must pass the appearance inspection.