Designations adopted in table. 50*:

a) shaped steel with a thickness of up to 11 mm, and upon agreement with the manufacturer - up to 20 mm; sheet - all thicknesses;

b) the requirement to limit the carbon equivalent according to GOST 27772-88 for thicknesses over 20 mm;

c) the requirement to limit the carbon equivalent according to GOST 27772-88 for all thicknesses;

d) for region II 4, for unheated buildings and structures operated at outdoor temperatures, use rolled products with a thickness of no more than 10 mm;

e) with a rolled product thickness of no more than 11 mm, category 3 steel may be used;

f) except for the supports of overhead lines, outdoor switchgear and KS;

g) rolled products up to 10 mm thick and taking into account the requirements of section. 10;

i) except for region II 4 for unheated buildings and structures operated at outside air temperature.

The "+" sign means that this steel should be used; the sign “—” means that this steel should not be used in the specified climatic region.

Notes: 1. The requirements of this table do not apply to steel structures of special structures: main and process pipelines, special-purpose tanks, casings of blast furnaces and air heaters, etc. Steels for these structures are established by the relevant SNiP or other regulatory documents.

2. The requirements of this table apply to sheet metal with a thickness of 2 mm and shaped steel with a thickness of 4 mm in accordance with GOST 27772-88, long products (round, square, strip) in accordance with TU 14-1-3023-80, GOST 380-71* * (since 1990 GOST 535-88) and GOST 19281-73*. The specified steel categories refer to rolled products with a thickness of at least 5 mm. With a thickness of less than 5 mm, the steels listed in the table are used without requirements for impact strength.

For structures of all groups, except for group 1 and supports of overhead lines and outdoor switchgear, in all climatic regions except I 1, it is allowed to use rolled products with a thickness of less than 5 mm from steel C235 in accordance with GOST 27772-88.

3. Climatic areas of construction are established in accordance with GOST 16350-80 "Climate of the USSR. Zoning and statistical parameters of climatic factors for technical purposes." The calculated temperatures indicated in the head of the table in brackets correspond to the outside air temperature of the corresponding area, which is taken to be the average temperature of the coldest five-day period in accordance with the instructions of SNiP for construction climatology and geophysics.

4. Structures that are directly exposed to dynamic, vibration or moving loads include structures or their elements that are subject to endurance calculations or calculated taking into account dynamic coefficients.

5. With an appropriate feasibility study, steels S345, S375, S440, S590, S590K, 16G2AF can be ordered as steels with increased corrosion resistance (with copper) - S345D, S375D, S440D, S590D, S590KD, 16G2AFD.

6. The use of heat-strengthened shaped bars made from steel S345T and S375T by rolling heating, supplied according to GOST 27772-88 as steel S345 and S375, is not allowed in structures that are subject to metallization or plastic deformation during manufacture at temperatures above 700°C.

7. Seamless hot-deformed pipes in accordance with GOST 8731-87 may be used only for elements of special supports of large transitions of power lines with a height of more than 60 m, for antenna communication structures and other special structures, and the following steel grades should be used:

in all climatic regions, except I 1, I 2, II 2 and II 3, grade 20 according to GOST 8731-87, but with an additional requirement for impact strength at a temperature of minus 20°C of at least 30 J/cm² (3 kgs×m/ cm²);

in climatic regions I 2, II 2 and II 3 - grade 09G2S according to GOST 8731-87, but with an additional requirement for impact strength at a temperature of minus 40°C of at least 40 J/cm² (4 kgf×m/cm²) for wall thickness up to 9 mm and 35 J/cm² (3.5 kgf×m/cm²) with a wall thickness of 10 mm or more.

It is not allowed to use seamless hot-deformed pipes made from ingots marked with the letter “L” that have not been tested by non-destructive methods.

8. For long products (round, square, strip) according to TU 14-1-3023-80, GOST 380-71* (since 1990 GOST 535-88) and GOST 19281-73* the same requirements are imposed as for shaped rolled products of the same thickness according to GOST 27772-88. The correspondence of steel grades according to TU 14-1-3023-80, GOST 380-71*, GOST 19281-73* and GOST 19282-73* to steels according to GOST 27772-88 should be determined from the table. 51, b.

STEEL STRUCTURES

SNiP II-23-81*

__________________

Introduced by TsNIISK them. Kucherenko Gosstroy USSR

Instead of SNiP II-V.3-72; SNiP II-I.9-62; CH 376-67

These standards were developed as a development of GOST 27751-88 “Reliability of building structures and foundations. Basic provisions for calculations" and ST SEV 3972-83 "Reliability of building structures and foundations. Steel structures. Basic provisions for calculation."

With the entry into force of these building codes and regulations, the following become invalid:

SNiP II-V.3-72 “Steel structures. Design standards";

changes to SNiP II-B.3-72 “Steel structures. Design standards” approved by the resolutions of the USSR State Construction Committee:

SNiP II-I.9-62 “Power transmission lines with voltage above 1 kV. Design standards" (section "Design of steel structures for overhead power transmission line supports");

changes to SNiP II-I.9-62 “Power transmission lines with voltage above 1 kV. Design standards”, approved by the Decree of the USSR State Construction Committee dated April 10, 1975;

“Guidelines for the design of metal structures of antenna structures of communication facilities” (SN 376-67).

Amendments were made to SNiP II-23-81*, approved by resolutions of the USSR State Construction Committee No. 120 of July 25, 1984, No. 218 of December 11, 1985, No. 69 of December 29, 1986, No. 132 of July 8, 1988. , No. 121 of July 12, 1989

The main letter designations are given in the appendix. 9*.

Sections, paragraphs, tables, formulas, appendices and captions to drawings to which changes have been made are marked in these building codes and regulations with an asterisk.

Editors - engineers F.M. Shlemin, IN.P. Poddubny(Gosstroy USSR), Doctor of Engineering. science prof. IN.A. Baldin, Ph.D. tech. sciences G.E. Velsky(TsNIISK Gosstroy USSR), engineer. E.M. Bukharin(“Energosetproekt” Ministry of Energy of the USSR), engineer. N.IN. Shevelev(SKB "Mosgidrostal" Ministry of Energy of the USSR).

When using a regulatory document, one should take into account the approved changes to building codes and regulations and state standards published in the journal “Bulletin of Construction Equipment”, “Collection of Amendments to Construction Codes and Rules” of the USSR State Construction Committee and the information index “USSR State Standards” of the USSR State Standard.

1. GENERAL PROVISIONS

1.1. These standards must be observed when designing steel building structures of buildings and structures for various purposes.

The standards do not apply to the design of steel structures for bridges, transport tunnels and pipes under embankments.

When designing steel structures under special operating conditions (for example, structures of blast furnaces, main and process pipelines, special-purpose tanks, structures of buildings exposed to seismic, intense temperature effects or exposure to aggressive environments, structures of offshore hydraulic structures), structures of unique buildings and structures, as well as special types of structures (for example, prestressed, spatial, hanging), additional requirements must be observed that reflect the operating features of these structures, provided for by the relevant regulatory documents approved or agreed upon by the USSR State Construction Committee.

1.2. When designing steel structures, one must comply with SNiP standards for the protection of building structures from corrosion and fire safety standards for the design of buildings and structures. Increasing the thickness of rolled products and pipe walls in order to protect structures from corrosion and increase the fire resistance of structures is not allowed.

All structures must be accessible for observation, cleaning, painting, and must not retain moisture or impede ventilation. Closed profiles must be sealed.

1.3*. When designing steel structures you should:

select optimal technical and economic schemes of structures and cross-sections of elements;

use economical rolled profiles and efficient steels;

use, as a rule, unified standard or standard designs for buildings and structures;

use progressive structures (spatial systems made of standard elements; structures combining load-bearing and enclosing functions; prestressed, cable-stayed, thin-sheet and combined structures made of different steels);

provide for the manufacturability of manufacturing and installation of structures;

use designs that ensure the least labor intensity of their manufacture, transportation and installation;

provide, as a rule, for the in-line production of structures and their conveyor or large-block installation;

provide for the use of progressive types of factory connections (automatic and semi-automatic welding, flanged connections, with milled ends, bolted connections, including high-strength ones, etc.);

provide, as a rule, mounting connections with bolts, including high-strength ones; welded installation connections are allowed with appropriate justification;

comply with the requirements of state standards for structures of the corresponding type.

1.4. When designing buildings and structures, it is necessary to adopt structural schemes that ensure the strength, stability and spatial immutability of buildings and structures as a whole, as well as their individual elements during transportation, installation and operation.

1.5*. Steels and connection materials, restrictions on the use of S345T and S375T steels, as well as additional requirements for the supplied steel provided for by state standards and CMEA standards or technical specifications, should be indicated in working (DM) and detailing (DMC) drawings of steel structures and in the documentation for ordering materials.

Depending on the characteristics of the structures and their components, it is necessary to indicate the continuity class in accordance with GOST 27772-88 when ordering steel.

1.6*. Steel structures and their calculations must meet the requirements of GOST 27751-88 "Reliability of building structures and foundations. Basic provisions for calculation" and ST SEV 3972-83 "Reliability of building structures and foundations. Steel structures. Basic provisions for calculation."

1.7. Design schemes and basic calculation assumptions must reflect the actual operating conditions of steel structures.

Steel structures should generally be designed as unified spatial systems.

When dividing unified spatial systems into separate flat structures, the interaction of the elements with each other and with the base should be taken into account.

The choice of design schemes, as well as methods for calculating steel structures, must be made taking into account the effective use of computers.

1.8. Calculations of steel structures should, as a rule, be carried out taking into account inelastic deformations of steel.

For statically indeterminate structures, the calculation method for which taking into account inelastic deformations of steel has not been developed, the design forces (bending and torsional moments, longitudinal and transverse forces) should be determined under the assumption of elastic deformations of steel according to an undeformed scheme.

With an appropriate feasibility study, the calculation can be carried out using a deformed scheme that takes into account the influence of structural movements under load.

1.9. Elements of steel structures must have minimum cross-sections that meet the requirements of these standards, taking into account the range of rolled products and pipes. In composite sections established by calculation, the undervoltage should not exceed 5%.

2. MATERIALS FOR STRUCTURES AND CONNECTIONS

2.1*. Depending on the degree of responsibility of the structures of buildings and structures, as well as on the conditions of their operation, all structures are divided into four groups. Steels for steel structures of buildings and structures should be taken according to table. 50*.

Steel for structures erected in climatic regions I 1, I 2, II 2 and II 3, but operated in heated rooms, should be taken as for climatic region II 4 according to Table. 50*, with the exception of steel C245 and C275 for group 2 construction.

For flange connections and frame assemblies, rolled products according to TU 14-1-4431-88 should be used.

2.2*. For welding steel structures, the following should be used: electrodes for manual arc welding in accordance with GOST 9467-75*; welding wire according to GOST 2246-70*; fluxes according to GOST 9087-81*; carbon dioxide according to GOST 8050-85.

The welding materials and welding technology used must ensure that the tensile strength of the weld metal is not lower than the standard tensile strength value R un base metal, as well as the values ​​of hardness, impact strength and relative elongation of the metal of welded joints, established by the relevant regulatory documents.

2.3*. Castings (supporting parts, etc.) for steel structures should be designed from carbon steel grades 15L, 25L, 35L and 45L, meeting the requirements for casting groups II or III according to GOST 977-75*, as well as from gray cast iron grades SCh15, SCh20, SCh25 and SCh30, meeting the requirements of GOST 1412-85.

2.4*. For bolted connections, steel bolts and nuts that meet the requirements of GOST 1759.0-87*, GOST 1759.4-87* and GOST 1759.5-87*, and washers that meet the requirements of GOST 18123-82* should be used.

Bolts should be assigned according to the table. 57* and GOST 15589-70*, GOST 15591-70*, GOST 7796-70*, GOST 7798-70*, and when limiting joint deformations - according to GOST 7805-70*.

Nuts should be used in accordance with GOST 5915-70*: for bolts of strength classes 4.6, 4.8, 5.6 and 5.8 - nuts of strength class 4; for bolts of strength classes 6.6 and 8.8 - nuts of strength classes 5 and 6, respectively, for bolts of strength class 10.9 - nuts of strength class 8.

The following washers should be used: round washers in accordance with GOST 11371-78*, oblique washers in accordance with GOST 10906-78* and normal spring washers in accordance with GOST 6402-70*.

2.5*. The choice of steel grades for foundation bolts should be made in accordance with GOST 24379.0-80, and their design and dimensions should be taken in accordance with GOST 24379.1-80*.

Bolts (U-shaped) for fastening guy wires of antenna communication structures, as well as U-shaped and foundation bolts for supports of overhead power lines and distribution devices should be used from steel grades: 09G2S-8 and 10G2S1-8 in accordance with GOST 19281-73* with an additional requirement for impact strength at a temperature of minus 60°C is not less than 30 J/cm 2 (3 kgf × m/cm 2) in climatic region I 1; 09G2S-6 and 10G2S1-6 according to GOST 19281-73* in climatic regions I 2, II 2 and II 3; VSt3sp2 according to GOST 380-71* (since 1990 St3sp2-1 according to GOST 535-88) in all other climatic regions.

2.6*. Nuts for foundation and U-bolts should be used:

for bolts made of steel grades VSt3sp2 and 20 - strength class 4 according to GOST 1759.5-87*;

for bolts made of steel grades 09G2S and 10G2S1 - strength class not lower than 5 according to GOST 1759.5-87*. It is allowed to use nuts made of steel grades accepted for bolts.

Nuts for foundation and U-bolts with a diameter of less than 48 mm should be used in accordance with GOST 5915-70*, for bolts with a diameter of more than 48 mm - in accordance with GOST 10605-72*.

2.7*. High-strength bolts should be used in accordance with GOST 22353-77*, GOST 22356-77* and TU 14-4-1345-85; nuts and washers for them - in accordance with GOST 22354-77* and GOST 22355-77*.

2.8*. For load-bearing elements of suspended coverings, guy wires for overhead lines and outdoor switchgears, masts and towers, as well as prestressing elements in prestressed structures, the following should be used:

spiral ropes according to GOST 3062-80*; GOST 3063-80*, GOST 3064-80*;

double lay ropes according to GOST 3066-80*; GOST 3067-74*; GOST 3068-74*; GOST 3081-80*; GOST 7669-80*; GOST 14954-80*;

closed load-bearing ropes according to GOST 3090-73*; GOST 18900-73* GOST 18901-73*; GOST 18902-73*; GOST 7675-73*; GOST 7676-73*;

bundles and strands of parallel wires formed from rope wire that meets the requirements of GOST 7372-79*.

2.9. The physical characteristics of materials used for steel structures should be taken in accordance with App. 3.

3. DESIGN CHARACTERISTICS OF MATERIALS AND CONNECTIONS

3.1*. The calculated resistances of rolled products, bent sections and pipes for various types of stress states should be determined using the formulas given in Table. 1*.

Table 1*

Tense state		Symbol	Calculated resistance of rolled products and pipes
stretching,	By yield strength		Ry = Ryn/gm
compression and bending	According to temporary resistance		R u = R un /gm
			R s = 0,58Ryn/gm
End surface collapse (if fitted)			Rp = R un /gm
Local crushing in cylindrical hinges (trunnions) upon tight contact			Rlp = 0,5R un /gm
Diametric compression of rollers (with free contact in structures with limited mobility)			Rcd = 0,025R un /gm
Tension in the direction of rolled product thickness (up to 60 mm)			R th = 0,5R un /gm
The designation adopted in table. 1*:
gm- reliability coefficient for the material, determined in accordance with clause 3.2*.

3.2*. The values ​​of reliability coefficients for rolled material, bent sections and pipes should be taken according to table. 2*.

Table 2*

State standard or technical conditions for rental	Reliability factor by material g m
GOST 27772-88 (except for steels S590, S590K); TU 14-1-3023-80 (for circle, square, strip)
GOST 27772-88 (steel S590, S590K); GOST 380-71** (for circles and squares with dimensions not included in TU 14-1-3023-80); GOST 19281-73* [for circles and squares with a yield strength of up to 380 MPa (39 kgf/mm 2) and dimensions not included in TU 14-1-3023-80];
GOST 10705-80*; GOST 10706-76*

GOST 19281-73* [for a circle and a square with a yield strength of over 380 MPa (39 kgf/mm 2) and dimensions not included in TU 14-1-3023-80]; GOST 8731-87; TU 14-3-567-76

The calculated resistances in tension, compression and bending of sheet, wide-band universal and shaped rolled products are given in table. 51*, pipes - in table. 51, a. The calculated resistances of bent profiles should be taken equal to the calculated resistances of the rolled sheets from which they are made, while it is possible to take into account the hardening of the rolled sheet steel in the bending zone. The design resistances of round, square and strip products should be determined according to table. 1*, taking values Ryn R un And

equal, respectively, to the yield strength and tensile strength according to TU 14-1-3023-80, GOST 380-71** (since 1990 GOST 535-88) and GOST 19281-73*.

The calculated resistance of rolled products to crushing of the end surface, local crushing in cylindrical hinges and diametric compression of the rollers are given in Table. 52*.

3.3. The calculated resistances of castings made of carbon steel and gray cast iron should be taken according to table. 53 and 54.

3.4. The calculated resistances of welded joints for various types of joints and stress states should be determined using the formulas given in Table. 3.

Table 3	Welded joints		Symbol	Voltage status
Calculated resistance of welded joints	Butt	By yield strength		Compression. Stretching and bending during automatic, semi-automatic or manual welding with physical quality control of seams = Ry
		According to temporary resistance		Rwy = R u
	Rwu	By yield strength		Compression. Stretching and bending during automatic, semi-automatic or manual welding with physical quality control of seams = 0,85Ry
				Stretching and bending during automatic, semi-automatic or manual welding = R s
Rws	With corner seams Slice (conditional) = 0,45R un
Notes: 1. For seams made by hand welding, the values R wun should be taken equal to the values ​​of the tensile strength of the weld metal specified in GOST 9467-75*. 2. For seams made by automatic or semi-automatic welding, the value R wun should be taken according to the table. 4* of these standards. 3. Reliability coefficient values ​​for weld material gwm should be taken equal to: 1.25 - with values R wun no more than 490 MPa (5,000 kgf/cm2); 1.35 - with values R wun 590 MPa (6,000 kgf/cm2) or more.

The calculated resistances of butt joints of elements made of steel with different standard resistances should be taken as for butt joints made of steel with a lower value of standard resistance.

The calculated resistances of the weld metal of welded joints with fillet welds are given in Table. 56.

3.5. The calculated resistances of single-bolt connections should be determined using the formulas given in table. 5*.

The calculated shear and tensile strengths of the bolts are given in Table. 58*, collapse of elements connected by bolts - in table. 59*.

3.6*. Design tensile strength of foundation bolts Rba

Rba = 0,5R. (1)

Design Tensile Strength of U-Bolts R bv, specified in clause 2.5*, should be determined by the formula

R bv = 0,45R un. (2)

The calculated tensile strength of foundation bolts is given in table. 60*.

3.7. Design tensile strength of high strength bolts Rbh should be determined by the formula

Rbh = 0,7Rbun, (3)

Where Rbun- the smallest temporary tensile strength of the bolt, taken according to the table. 61*.

3.8. Design tensile strength of high tensile steel wire Rdh, used in the form of bundles or strands, should be determined by the formula

Rdh = 0,63R un. (4)

3.9. The value of the calculated resistance (force) to tension of a steel rope should be taken equal to the value of the breaking force of the rope as a whole, established by state standards or technical specifications for steel ropes, divided by the reliability coefficient g m = 1,6.

Free download SNiP II-23-81 * - Steel structures

SNiP II-23-81 *

1. GENERAL PROVISIONS

1.1. These standards must be observed when designing steel building structures of buildings and structures for various purposes.
The standards do not apply to the design of steel structures for bridges, transport tunnels and pipes under embankments.
When designing steel structures under special operating conditions (for example, structures of blast furnaces, main and process pipelines, special-purpose tanks, structures of buildings exposed to seismic, intense temperature effects or exposure to aggressive environments, structures of offshore hydraulic structures), structures of unique buildings and structures, as well as special types of structures (for example, prestressed, spatial, hanging), additional requirements must be observed that reflect the operating features of these structures, provided for by the relevant regulatory documents approved or agreed upon by the USSR State Construction Committee.
1.2. When designing steel structures, one must comply with SNiP standards for the protection of building structures from corrosion and fire safety standards for the design of buildings and structures. Increasing the thickness of rolled products and pipe walls in order to protect structures from corrosion and increase the fire resistance of structures is not allowed.
All structures must be accessible for observation, cleaning, painting, and must not retain moisture or impede ventilation. Closed profiles must be sealed.