Steel structure engineering company analyzes steel structure material requirements

Steel structure engineering company analyzes steel structure material requirements

Steel structures are widely used in various engineering constructions, such as steel bridges, steel workshops, steel gates, various Due to the special application field, steel structure engineering companies have certain requirements for steel structure materials.

1. Strength

The strength index of steel consists of elastic limit σe, yield limit σy, and tensile limit σu, The design is based on the yield strength of the steel. High yield strength can reduce the self-weight of the structure, save steel and reduce the cost. The tensile strength σu is the maximum stress that the steel can withstand before it is damaged. At this time, the structure loses its performance due to large plastic deformation, but the structural deformation is large and does not collapse, which meets the requirements of the structure to resist rare earthquakes. The value of 'σu/σy can be regarded as the parameter of steel strength reserve.

2. Plasticity

The plasticity of steel generally means that after the stress exceeds the yield point, there is a significant plastic deformation without nature of fracture. The main indicators to measure the plastic deformation capacity of steel are elongation δ and area shrinkage ψ.

3. Cold bending performance

The cold bending performance of steel is a measure of the bending process of steel at room temperature Resistance to cracking when plastic deformation occurs. The cold bending performance of steel is to use the cold bending test to test the bending deformation performance of the steel under the specified bending degree.

4. Impact toughness

The impact toughness of steel refers to the impact toughness of steel in the process of absorbing mechanical An ability of kinetic energy is a mechanical property that measures the resistance of steel to impact load, which may lead to brittle fracture due to low temperature and stress concentration. Generally, the impact toughness index of steel is obtained through the impact test of standard specimens.

5. Welding Properties welded joints. Welding performance can be divided into welding performance in welding process and welding performance in use performance. Welding performance during welding refers to the sensitivity that the weld and the metal near the weld do not produce hot cracks or cooling shrinkage cracks during the welding process. Good welding performance means that under certain welding process conditions, neither the weld metal nor the nearby base metal cracks. The welding performance in terms of performance refers to the impact toughness at the weld and the ductility in the heat-affected zone. It is required that the mechanical properties of the weld and the steel in the heat-affected zone are not lower than the mechanical properties of the base metal. In my country, the welding performance test method of the welding process is adopted, and the welding performance test method of the usable nature is also adopted.

6. Durability

There are many factors that affect the durability of steel. First of all, the corrosion resistance of steel is poor, and protective measures must be taken to prevent the steel from corroding and rusting. The protective measures include: regular maintenance of the steel paint, the use of galvanized steel, special protective measures in the presence of strong corrosive media such as acid, alkali, salt, etc., such as the use of 'anodic protection' measures for the structure of the offshore platform to prevent the corrosion of the jacket. A zinc ingot is fixed on the jacket, and the seawater electrolyte will automatically corrode the zinc ingot first, thus achieving the function of protecting the steel jacket. Secondly, because the failure strength of steel under high temperature and long-term load is much lower than the short-term strength, the permanent strength of steel under long-term high temperature should be measured. Steel will automatically harden and become brittle over time, a phenomenon known as 'aging'. The impact toughness of steel under low temperature load should be tested.