Basic knowledge of steel structure

1. The steel structure system has the comprehensive advantages of light weight, easy installation, short construction period, good seismic performance, fast investment recovery, less environmental pollution, good plasticity and toughness, and good impact resistance.

2. The types of steel include: thin plate (thickness of thin steel plate<14mm), medium plate (thickness of medium plate 14-20mm) and thick plate (thickness of 20-60mm) greater than 60, which are classified as extra thick. The steel strip is included in the steel plate category.

3. What is the difference between ordinary bolts and high-strength bolts?

Ordinary bolts are generally made of ordinary carbon structural steel without heat treatment. High strength bolts are generally made of high-quality carbon structural steel or alloy structural steel, which requires quenching and tempering heat treatment to improve the comprehensive mechanical properties. High strength is divided into 8.8S, 10.9S and 12.9S.

From the strength grade: high-strength bolts are generally used in 8.8S and 10.9S strength grades. Ordinary bolts generally have grade 4.4, 4.8, 5.6 and 8.8.

High strength bolts exert pre tension and transfer external force by friction force according to the stress characteristics, while ordinary bolts transfer shear force by bolt rod shear resistance and hole wall bearing.

4. It can be divided into friction type and pressure bearing type according to stress characteristics

Friction type high-strength bolt transfers the external force according to the friction between the connected parts. When the shear force is equal to the friction force, it is the design limit load of extremely friction type high-strength bolt connection. At this time, the members of Lianzhong will not slip, the bolt rods will not be sheared, and the bolt hole wall will not bear pressure.

The bearing type high-strength bolt is similar to the ordinary bolt. The shear force can exceed the friction force. At this time, there will be relative slip between the connected components. The bolt rod contacts the hole wall. The connection relies on the friction force and the shear and bearing force of the bolt rod to transmit the force together.

The deformation of bearing type high-strength bolt is large, and it is not suitable for the connection of structures directly bearing dynamic load.

5. Types of welding rods

There are about a dozen kinds: carbon steel electrode, low alloy steel electrode, molybdenum and chromium molybdenum heat-resistant steel electrode, low temperature steel electrode, stainless steel electrode, surfacing electrode, cast iron electrode, nickel and nickel alloy electrode, copper and copper alloy electrode, aluminum and aluminum alloy electrode and special purpose electrode.

6. Procedures for parts processing: preparation, correction, setting out, cutting, bending, hole making, assembly, welding, detection, rust removal and painting.

7. There are four rust removal methods for metal surface: manual treatment, mechanical treatment, chemical treatment and flame treatment.