Steel for high-rise buildings

High-performance building structural steel is the full name. It has the properties of easy welding, earthquake resistance, and low-temperature impact resistance. It is mainly used in large-scale construction projects such as high-rise buildings, super-high-rise buildings, large-span stadiums, airports, exhibition centers, and steel structure workshops. Compared with ordinary carbon or low-alloy steel plates, high-rise steel plates have an upper limit on yield strength, improved tensile strength, and requirements for carbon equivalent and yield strength ratio. High-rise plates are usually produced by medium and thick plate mills, but it is not ruled out that they are produced by furnace coil mills and hot rolling mills. High-rise plates are mainly some extra-thick plates, thick plates, medium plates, and medium plates. Generally speaking, the thickness of structural steel plates for high-rise buildings is 10-100MM, the width is 1600-3500MM, and the length is 6000-18000MM.

The stress conditions of steel used in high-rise buildings are complex, and it is required to have high safety and reliability, long service life, and be able to withstand the damage of a certain earthquake intensity. This determines that the steel plates used in high-rise building structures are required to have certain special properties, mainly the following:

(1) It must be able to withstand the damage of a certain earthquake force and be earthquake-proof and earthquake-resistant. To this end, the steel plate must not only have sufficient tensile strength and yield strength, but also have a low yield strength ratio. A low yield strength ratio can enable the material to have good cold deformation ability and high plastic deformation work, absorb more earthquake energy, and improve the earthquake resistance of the building.

(2) It must have good welding performance, so that no preheating is required before welding and no heat treatment is required after welding, so as to facilitate on-site welding, thereby reducing labor intensity and improving labor efficiency.

(3) It must have high plasticity and toughness so that the steel plate has good mechanical properties.

(4) It must have a small yield strength fluctuation range. When the yield strength fluctuation range is large, the matching of the yield strength between the various parts of the building may be different from the design requirement value, which is easy to cause local damage and reduce the earthquake resistance of the building. Therefore, the Japanese standard stipulates that the yield strength fluctuation range is not more than 120MPA.

(5) Within the range of the beam and column nodes connected by welding, when the node constraints are strong and bear the tensile force along the plate thickness direction, the steel plate must have a certain level of anti-layer tearing ability.

Product classification

The grades of high-rise building plates are divided into five strength levels: yield point 235MPA, 345MPA, 390MPA, 420MPA and 460MPA. Each strength level is divided into Z-direction and non-Z-direction steel. Z-direction steel has three grades: Z15, Z25 and Z35. Each grade is divided into quality grades according to different impact test requirements. All grades have good welding performance. According to the recommended standards of the Ministry of Metallurgy and the national standards for steel plates for building structures, the main varieties of high-rise building plates in my country are: Q235GJB/C/D and Q345GJB/C/D, and the national standard implemented is GB/T19879-2005 "Steel Plates for Building Structures". The above-mentioned high-rise building plates are gradually developed with the technological progress and development requirements of high-rise building construction in my country.

According to the provisions of GB/T221 "Method for Representing Steel Product Grades" and the representation method of carbon steel and low-alloy high-strength steel for engineering structures, considering the characteristics of steel for building structures and highlighting high-rise buildings, the grade when ordering is composed of the Chinese pinyin letters representing high-performance building structure steel and yield point, the yield point value of the steel plate, and the quality grade symbol. For steel plates with performance in the thickness direction, the performance level in the thickness direction is added after the quality grade symbol, such as Q345GJCZ25, where Q, G, and J are the first Chinese pinyin letters of yield point, high-rise, and building respectively; 345 is the yield point value, unit MPA; Z25 is the performance level in the thickness direction; C is the quality grade, corresponding to the impact test temperature of 0℃

Product Use

Since 1996, Anshan Iron and Steel has started to develop steel plates for high-rise building structures on a large scale. The development and production of steel plates for building structures has reached 120,000 tons, and the yield strength level has reached 460MPA. Steel structure buildings have emerged in Europe since the 1950s. With its special advantages such as superior earthquake resistance, environmental protection, high construction efficiency, and high space utilization, it has now become the development direction of international building structures. In recent years, my country has built a large number of steel structure buildings. Before 1996, steel was basically imported, but now it has been domestically produced on a large scale. The safety of steel structure buildings is very important, and there are special technical requirements for the steel used. The application of high-rise building plates can greatly adapt to and support the development of building structures towards high-rise and large spans, so as to reduce the weight of the structure, reduce the construction cost, reduce the thickness of the steel structure materials, and improve its manufacturing reliability.