Specification and model of reinforcement
The specification range of thread is generally 6-50mm, and we usually involve 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, etc. National allowable deviation: 6- 12mm deviation is 7%, 14-20mm deviation is 5%, and 22-50mm deviation is 4%.
Specification and appearance quality
1, steel bar
The grade of hot-rolled ribbed bar consists of HRB and the minimum yield point of this grade. H, r and b are the initials of the words Hotrolled, Ribbbed and Bars respectively. Hot rolled ribbed bars are divided into three brands: HRB335 (old brand name 20MnSi), HRB400 (brand names 20mnsini, 20msinb and 20MnTi) and HRB500.
Steel bars for reinforced concrete refer to straight steel bars or rolled steel bars used to strengthen reinforced concrete. Its shape can be divided into smooth circular reinforcement and deformed reinforcement, and the delivery state is straight and coiled. ? Smooth round steel is actually a small round steel and coil of ordinary low carbon steel. Deformed steel bar is a steel bar with ribs on the surface, which generally has two longitudinal ribs and along? Transverse ribs evenly distributed along the length direction. The shapes of transverse ribs are spiral, herringbone and crescent. Expressed in millimeters of nominal diameter. The nominal diameter of deformed steel bar is equivalent to the nominal diameter of smooth round steel with equal cross section. The nominal diameter of reinforcement is 8-50 mm, and the recommended diameters are 8, 12, 16, 20, 25,? 32,40 mm. Steel grade: 20MnSi, 20MnV, 25MnSi, BS20MnSi. Steel bars mainly bear tensile stress in concrete. Deformed steel bars have great bonding ability with concrete due to the action of ribs, so they can better withstand the action of external forces. Steel bars are widely used in various building structures, especially large, heavy, light thin-walled and high-rise building structures.
Product standard: (GB1499-1991,BS4449: 1988)
Specification: 8, 10, 12, 14, 16,18,20,22,25,28,32,36,40,50 mm.
In the production process, vanadium, niobium, titanium and other alloys are added to the new vanadium-containing third-grade rebar rod (20 MnS uli, 400Mpa). Compared with ordinary grade II rebar, it has the advantages of high strength, good toughness, good weldability and good seismic performance. In the construction market of developed countries such as Europe, grade ⅲ rebar accounts for 80% of the total rebar. 1995, the former Ministry of Metallurgy and the Ministry of Construction jointly issued a document to promote its application, and the Ministry of Construction incorporated the technical conditions of new grade III threaded steel bars into the national standard GBJ 10-89 Code for Design of Concrete Structures.
Advantages of V-bearing Grade Ⅲ rebar
A. Economy: Compared with the second grade rebar, the new third grade rebar can save steel 10- 15% due to its high strength, thus reducing the construction cost of building projects.
B, high strength and good toughness: after microalloying treatment, the yield point is above 400Mpa, and the tensile strength is above 570Mpa, which is 20% higher than that of secondary rebar.
C. Earthquake resistance: Vanadium-containing steel bars have high bending resistance, aging resistance and low cycle fatigue performance, and the earthquake resistance is obviously superior to grade II rebar.
D, easy welding: because the carbon content is less than or equal to 0.54%, it has good welding performance, is suitable for various welding methods, and the process is simple and convenient.
E. Convenient construction: new three-level threaded steel bars are adopted to increase the construction gap and ensure the convenience and quality of construction.
Specification and model of reinforcement
(1) Specification: The specification requirements of steel bars shall be specified in the import and export trade contract. Generally should include the standard brand (type code? ), nominal diameter, nominal weight (mass), specified length and tolerance of the above indicators, etc. China Standard recommends rebar series with nominal diameters of 8, 10, 12, 16, 20 and 40mm. Supply length is divided into fixed length and double length. The selection range of rebar length for export in China is 6 ~ 12m, and that for Japanese rebar is 3.5 ~ 10m.
(2) Appearance quality: ① Surface quality. The surface quality of steel bars is stipulated in relevant standards, requiring that the ends should be cut flat? Straight, the surface must not have cracks, scars, folds, and no harmful defects in use; ② Allowable value of size deviation? . The requirements for the bending degree and geometric shape of steel bars are stipulated in the relevant standards. According to Chinese standards, the bending degree of straight steel bar is not more than 6mm/m, and the total bending degree is not more than 0.6% of the total length of steel bar. ? Standard number? GB 1499- 1998？ GB 700-88 (carbon structural steel); GB/T？ 2 10 1-89 (steel acceptance? General provisions on packaging, marks and quality certificates); GB 1499—9 1 (reinforcement for concrete); JIS？ G3 1 12—87(98) (rebar for reinforced concrete); JIS G3191-66 (94) (shape, size, weight and allowable deviation of hot rolled bars and coils); BS 4449-97 (Hot rolled steel bars for concrete structures). ? Chemical composition? Cards? Number? Chemical composition, 100%? c？ Is it? Mn？ p？ s？ Ceq？ HRB335？ 0.25? 0.80? 1.60? 0.045? 0.045? 0.52? HRB400？ 0.25? 0.80? 1.60? 0.045? 0.045? 0.54? HRB500？ 0.25? 0.80? 1.60? 0.045? 0.045? 0.55
This paper introduces the specifications and models of steel bars for reference. I hope it will help everyone!
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