Steel varieties and specifications for building steel structure

1. The main plate and strip steel for structure are: hot steel plate and steel strip, cold rolled steel plate and steel strip. The application range of the thickness of the hot rolled steel plate is 4~200mm, and the application range of the thickness of the hot steel strip is 4~ 25mm. The application range of cold rolled steel plate thickness is 0.2~5 mm, and the application range of cold rolled steel strip thickness is not more than 3 mm.

2. Hot rolled H-beams and welded H-beams. Widely used in building steel structure. Hot rolled H-shaped steel is divided into wide flange, middle flange and narrow flange two specifications.

3. Ordinary profiles (I-steel, channel steel, Angle steel). I-beam steel, channel steel and Angle steel are the earliest used section steel in steel structure. The type of I-beam and channel steel is expressed by the number of centimeters of the height of the section, and its length is usually 5 to 19 m. Angle steel is the most widely used rolled profile in the traditional lattice steel structure members, there are equal Angle steel and unequal Angle steel two categories, the length is usually 4~19 m.

4. Cold formed steel. Cold-formed steel is the cold-processed profile generated by thin steel plate (steel strip) on the continuous silver cold-formed unit, which can be processed with a wall thickness of 1.5~6 mm. With the development of the production process, cold-formed steel with a thickness of more than 12 mm can now be produced. The section forms are equal Angle steel, rolled equal Angle steel, Z steel, rolled Z steel, C steel, rolled C steel and other open sections as well as square and rectangular closed section of the pipe.

5. Thickness direction performance steel plate. With the increase of the thickness of steel plate used in welding structure, a new content of steel material properties is put forward - the steel plate is required to have good laminar tear resistance in the thickness direction. The performance requirements for building steel structure and bridge steel structure are proposed in the direction of plate thickness. There are three levels of thickness direction performance, respectively denoted by Z15, Z25 and Z35, respectively denoting section shrinkage of 215, 25 and 35.

6. Steel pipe for structure. Structural steel pipes have two categories: hot-rolled seamless steel pipes and welded steel pipes. Welded steel pipe is made of steel strip coil welding, and according to the diameter of the pipe, it is divided into straight seam welding and spiral welding. The structure is divided into two kinds of seamless steel pipes: hot and cold drawn.

7. Other steel products of building steel structures include patterned steel plates, steel grating plates and mesh ball nodes

The patterned steel plate is a diamond shaped, lentil shaped, or round bean shaped steel product made of carbon structural steel, hull structural steel and high weather resistance structural steel.

The pressure welded steel grid plate is a steel grid plate made of loaded flat steel as a longitudinal bar and twisted square steel as a transverse bar, which is pressed and welded to the longitudinal bar in the orthogonal direction and has a wrapped edge and a guard plate.

Steel grid ball joints are divided into two categories: bolt ball joints and welded ball joints. 1. The grade of steel should generally be selected from the carbon structural steel Q235 and low-alloy high-strength steel Q345 recommended by the design specification, and when there is a reasonable basis, the low-alloy high-strength steel Q390 or Q420 with higher strength can also be selected.

"Steel structure design Code" GB 50017-2003 in 3.3,1 provisions, bearing structure steel should be used 0235 steel, 0345, 390 steel and 0420 steel, the amount should be in line with the current national standard "carbon structural steel" GB/T700 and "low alloy high strength structural steel" GB/T1591 provisions. When using other grades of steel, it should meet the provisions and requirements of the corresponding relevant standards

JGJ99-98, the "Technical Regulations for Civil Steel structures in high-rise Buildings", stipulates that the steel of steel structures in high-rise buildings should be carbon structural steel of Q235 grade B, C and D, and low-alloy high-strength structural steel of Q345 grade B, C, D and E. Its quality standards should be in line with China's current national standard "carbon structural steel" (GB/T700), "low alloy high strength structural steel" GB/T1591, when there is a reliable basis for the use of other grades of steel

Technical Regulations for Steel Structure of light housing with Portal Steel Frame CECS102!

For the cold-formed thin-wall steel, light hot-rolled steel and steel plates used for load-bearing, Q235 steel specified in GB/T700 of the current national standard "Carbon structural steel" and Q345 steel specified in GB/T1591 of "low alloy high-strength structural steel" should be adopted.

2 Gantry rigid frame, crane beam, welded brown bar, wall beam and other components should be Q235B or Q345A and above grade steel. Non-welded brown strips and wall beams can be made of Q235A steel. When there is evidence, portal frame, brown strip and wall beam can be made of other grades of steel.

The "Cold-formed thin-wall steel structure Technical Specification" GB50018 stipulates that the strip or steel plate of cold-formed thin-wall steel used for load-bearing structures should be Q235 steel in line with the current national standard "Carbon structural steel" GB/T700 and "alloy high-strength structural steel" GB/T1591 Q345 steel. Other grades of steel can be used when there is a reliable basis, but it should meet the requirements of the relevant national standards

2. The performance and quality requirements of the steel used in the steel structure members should consider the importance of the structure, load characteristics (whether to bear dynamic load), connection method (welded or non-welded structure), ambient temperature (whether to work at low temperature) and steel thickness and other factors, and the correct and reasonable selection

3. Q235-A steel should not be used for welding load-bearing structures

4. For load-bearing steel structures with seismic fortification calculations, the steel properties shall meet the following requirements:

1) The yield ratio of steel, that is, the ratio of tensile strength to yield strength should not be less than 1.2:

2) The steel should have an obvious yield step, and the elongation (65) should be greater than 20%

3) It has good weldability and qualified impact toughness

(5) The design of industrial and civil building steel structures with a safety level and a class of earthquake-resistant building steel structures, and the quality grade of the main load-bearing structure (frame, girder, main frame) steel should not be lower than C, and carbon equivalent (Ceq) additional guarantees can be required if necessary

6. Important bearing steel structure (high-rise or multi-layer steel structure frame, etc.) welding joints, when the thickness of the section plate t240mm, and withstand the thickness of the plate direction tension (tearing), the part or member of the steel should be in accordance with the "thickness direction performance steel plate" GB5313 provisions. Additional guaranteed section shrinkage (Z15, Z25, Z35 levels), generally can be selected according to Z15 or Z25 two levels

7. For the main load-bearing welded components of high-rise structures or large-span steel structures, the plates should be made of Q235GJZ steel or Q345GJZ steel conforming to the GB/T19879-2005 standard of "Steel Plates for Building Structures". When the thickness of the plates used is greater than or equal to 40mm and the performance requirements of the tear resistance direction, The steel in this part should use Q235GJZ steel or Q345GJZ steel in the standard to ensure directional performance

8. In the outdoor corrosive environment, the load-bearing steel structure members can be selected as the weathering steel required by GB4172 for Welding structure. When weathering steel is selected for the bearing steel structure, the surface should still be treated with rust removal and coating.

These are the main steel used in building steel structures. The structure made mainly of steel is one of the main building structure types. Steel is characterized by high strength, light weight, stiffness, so the steel structure is especially suitable for the construction of large span and high height, large load structure is also most suitable for mobile, disassembly requirements of the structure, the material plasticity and toughness is good, in the case of overload will not break, withstand large deformation, can withstand the dynamic load, material homogeneity and isotropy good, ideal elastomer, Most in line with the basic assumptions of general engineering mechanics; The highest degree of industrial production, high manufacturing precision, convenient construction, short cycle, its disadvantage is that the fire resistance and corrosion resistance is poor. It is mainly used for load-bearing skeleton of heavy workshop, powerhouse structure under dynamic load, plate and shell structure, tall TV tower and mast structure, bridge and library and other long-span structure, high-rise and super high-rise building. Steel structure in the future should study high-strength steel, greatly improve its yield point strength, because of these characteristics of steel structure, it will occupy a very important position in construction.