Abstract:Steel Structure Materials is one of the main types of building structure, which is commonly used with traditional wood structure, concrete structure and brick concrete structure.
Structural steel materials are structures made up of steel and are one of the main types of building structures.
Structural steel materials have been used reasonably extensively throughout the world, particularly in the field of development and regional building projects.
The steel construction industry is usually divided into five sub-categories: light steel structures, high-rise steel structures, residential steel structures, space steel structures and bridge steel structures.
The main structural materials are beams made of section steel and aluminium, steel trusses, the use of methicone alkyl phosphorus, chemical water column and other enterprises, the use of methicone alkyl phosphorus, water pure and pure process, steel in addition to silicon and other steel materials.
Steel structures are mainly used in bridges, buildings, lighthouses, ships and other fields.
In addition to steel structure, there are wood structure, concrete structure, brick concrete structure and other structures.
The strength index of steel is determined by the elastic limit σ e the yield limit σ y. and the tensile limit σ u. The design is based on the yield strength of the steel.
A high yield strength reduces the dead weight of the structure, saves steel and reduces costs. The tensile strength σ U is the maximum stress that the steel can withstand before it fails.
At this point the structure loses its serviceability due to high plastic deformation.
However, the structure is deformed and does not collapse, meeting the requirements of a structure resistant to rare earthquakes
The plasticity of steel is generally defined as the property of having significant plastic deformation without fracture after the stress exceeds the yield point.
The main indicators of the ability to measure the plastic deformation of steel are elongation δ and section shrinkage ψ.
Cold bending performance of steel is a measure of the steel at room temperature when bending plastic deformation crack resistance.
Cold bending performance of steel is tested by cold bending test to test the bending deformation performance of steel in the specified bending degree.
Impact toughness of steel is the ability of steel to absorb mechanical kinetic energy in the fracture process under the impact load.
It is a measure of the resistance of steel to impact load cutting of a mechanical property, it may lead to brittle fracture due to low temperature and stress concentration.
The general steel impact toughness index is obtained by impact testing of standard specimens.
The weldability of steel refers to the welded joints with good performance under certain welding process conditions.
The weldability can be divided into the weldability in the welding process and the weldability in the use performance.
Weldability in the welding process refers to the sensitivity of the weld and the metal near the weld not to produce thermal cracking or cold shrinkage cracking during the cooling process.
Good welding performance refers to the absence of cracks in the weld metal and the nearby base material under certain welding process conditions.
The welding properties in the use of performance refers to the impact toughness and heat-affected zone ductility at the weld.
The mechanical properties of the weld and heat-affected zone steel are required to be no lower than those of the parent material.
China uses the welding process welding performance test method and availability welding performance test method.
6. Durability
There are a number of factors that affect the durability of steel.
1). One is the poor corrosion resistance of steel, which must be protected against corrosion and rusting.
2). Protective measures include: regular maintenance of steel paint, the use of galvanized steel, in acid, alkali, salt and other strong corrosive media conditions to take special protective measures.
3). If the offshore platform structure uses “anodic protection” measures to prevent jacket corrosion, zinc ingots are fixed to the jacket and the seawater electrolyte will first automatically corrode the zinc ingots, thus achieving functional protection of the steel jacket.
4). Secondly, the enduring strength of steel at high temperatures and long-term loads should be measured, as the strength of steel at high temperatures and long-term loads is much lower than the strength of steel at short-term loads.
5). Steel automatically hardens and becomes brittle over time, i.e. the phenomenon of “ageing”.
The impact toughness of steel should be tested under low temperature loading.
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