Instead, snip i 2 construction terminology. Centrally stretched and centrally compressed elements

SNiP II-23-81*
In return
SNiP II-V.3-72;
SNiP II-I.9-62; CH 376-67

STEEL STRUCTURES

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 features of structures and their components, it is necessary to indicate the continuity class of steel when ordering.

1.6*. Steel structures and their calculations must meet the requirements of "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 calculations."

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 should be used according to TU 14-1-4431 – 88.

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 Run 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 should be used that meet the requirements *, GOST 1759.4 – 87* and GOST 1759.5 – 87*, and washers that meet the requirements*.

Bolts should be assigned according to Table 57* and *, *, GOST 7796-70*, GOST 7798-70*, and when limiting the deformation of connections - 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.

Washers should be used: round according to GOST 11371 – 78*, oblique according to GOST 10906 – 78* and spring normal according to GOST 6402 – 70*.

2.5*. The choice of steel grades for foundation bolts should be made according to, and their design and dimensions should be taken according to *.

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 according to GOST 19281 – 73* with an additional requirement for impact strength at a temperature of minus 60 ° C 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 – according to GOST 10605 – 72*.

2.7*. High-strength bolts should be used according to *, * and TU 14-4-1345 – 85; nuts and washers for them – according to GOST 22354 – 77* and *.

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	R y = R yn /g m
compression and bending	According to temporary resistance	R u	R u = R un /g m
		R s	R s = 0.58Ryn/ g m
End surface collapse (if fitted)		Rp	R p = R un /g m
Local crushing in cylindrical hinges (trunnions) upon tight contact		Rlp	Rlp= 0.5Run/ g m
Diametric compression of rollers (with free contact in structures with limited mobility)		R cd	R cd= 0.025Run/ g m
Tension in the direction of rolled product thickness (up to 60 mm)		R th	R th= 0.5Run/ g m
The designation adopted in table. 1*:
g m - 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
(except for steels S590, S590K); TU 14-1-3023 – 80 (for circle, square, stripe)	1,025
(steel S590, S590K); GOST 380 – 71** (for a circle and a square with dimensions not included in TU 14-1-3023 – 80); GOST 19281 – 73* [for a circle and a square with a yield strength of up to 380 MPa (39 kgf/mm 2) and dimensions not included in TU 14-1-3023 – 80]; *; *	1,050
GOST 19281 – 73* [for a circle and a square with a yield strength 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	1,100

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 And Run 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	Voltage state		Symbol	Calculated resistance of welded joints
Butt	Compression. Tension and bending during automatic, semi-automatic or manual welding with physical	By yield strength	Rwy	Rwy=Ry
	seam quality control	According to temporary resistance	Rwu	Rwu= R u
	Tension and bending during automatic, semi-automatic or manual welding	By yield strength	Rwy	Rwy= 0.85Ry
	Shift		Rws	Rws= R s
With corner seams	Slice (conditional)	For weld metal	Rwf
		For metal fusion boundaries	Rwz	Rwz= 0.45Run
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 of R wun should be taken according to table. 4* of these standards. 3. Reliability coefficient values ​​for weld material g wm should be taken equal to: 1.25 – at values R wun no more than 490 MPa (5,000 kgf/cm2); 1.35 – at 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 = 0,45Run. (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 = 0,63Run. (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.

Table 4*

Wire grades (according to GOST 2246 – 70*) for automatic or semi-automatic welding		Powder grades	Standard values
submerged (GOST 9087 – 81*)	in carbon dioxide (according to GOST 8050 – 85) or in its mixture with argon (according to GOST 10157 – 79*)	wires (according to GOST 26271 – 84)	weld metal resistance R wun, MPa (kgf/cm 2)
Sv-08, Sv-08A	–	–	410 (4200)
	–	–	450 (4600)
	Sv-08G2S	PP-AN8, PP-AN3	490 (5000)
Sv-10NMA, Sv-10G2	Sv-08G2S*	–	590 (6000)
Sv-09HN2GMYU	Sv-10ХГ2СМА Sv-08ХГ2ДУ	–	685 (7000)
* When welding with wire Sv-08G2S values R wun should be taken equal to 590 MPa (6000 kgf/cm 2) only for fillet welds with leg kf £ 8 mm in structures made of steel with a yield strength of 440 MPa (4500 kgf/cm2) or more.

Table 5*

		Design resistances of single-bolt connections
Tense state	Symbol	shear and tension of class bolts			collapse of connected steel elements with a yield strength of up to 440 MPa
		4.6; 5.6; 6.6	4.8; 5.8	8.8; 10.9	(4500 kgf/cm 2)
	Rbs	R bs = 0.38R bun	Rbs= 0.4R bun	Rbs= 0.4R bun	–
Stretching	R bt	R bt s = 0.38R bun	R bt = 0.38R bun	R bt = 0.38R bun	–
	Rbp
a) bolts of accuracy class A		–	–	–
b) class B and C bolts		–	–	–
Note. It is allowed to use high-strength bolts without adjustable tension made of steel grade 40X “select”, while the calculated resistance Rbs And R bt should be determined as for bolts of class 10.9, and the design resistance as for bolts of accuracy classes B and C. High-strength bolts according to TU 14-4-1345 – 85 can only be used when working in tension.

4*. ACCOUNTING OPERATING CONDITIONS AND PURPOSE OF STRUCTURES

When calculating structures and connections, the following should be taken into account: reliability coefficients for the intended purpose g n adopted in accordance with the Rules for taking into account the degree of responsibility of buildings and structures when designing structures;

reliability factor g u= 1.3 for structural elements calculated for strength using design resistances R u;

working conditions coefficients g c and connection operating condition coefficients g b , taken according to the table. 6* and 35*, sections of these standards for the design of buildings, structures and structures, as well as app. 4*.

Table 6*

Structural elements	Working conditions coefficients g with
1. Solid beams and compressed elements of floor trusses under the halls of theaters, clubs, cinemas, under stands, under the premises of shops, book depositories and archives, etc. with the weight of the floors equal to or greater than the live load	0,9
2. Columns of public buildings and supports of water towers	0,95
3. Compressed main elements (except for supporting ones) of a composite T-section lattice from the corners of welded covering and ceiling trusses (for example, rafters and similar trusses) with flexibility l ³ 60	0,8
4. Solid beams when calculating general stability at j b 1,0	0,95
5. Tightenings, rods, braces, pendants made of rolled steel	0,9
6. Elements of core structures of coatings and ceilings:
a) compressed (with the exception of closed tubular sections) in stability calculations	0,95
b) stretched in welded structures	0,95
c) tensile, compressed, as well as butt linings in bolted structures (except for structures with high-strength bolts) made of steel with a yield strength of up to 440 MPa (4500 kgf/cm 2), bearing a static load, in strength calculations	1,05
7. Solid composite beams, columns, as well as butt plates made of steel with a yield strength of up to 440 MPa (4500 kgf/cm2), bearing a static load and made using bolted connections (except for connections with high-strength bolts), in strength calculations	1,1
8. Sections of rolled and welded elements, as well as linings made of steel with a yield strength of up to 440 MPa (4500 kgf/cm2) at joints made with bolts (except for joints with high-strength bolts) bearing a static load, in strength calculations:
a) solid beams and columns	1,1
b) core structures and floors	1,05
9. Compressed lattice elements of spatial lattice structures from single equal-flange (attached by a larger flange) corners:
a) attached directly to the belts with one flange using welds or two or more bolts placed along the corner:
braces according to fig. 9*, a	0,9
spacers according to fig. 9*, b, V	0,9
braces according to fig. 9*, in, G, d	0,8
b) attached directly to the belts with one shelf, one bolt (except for those indicated in item 9, in this table), and also attached through a gusset, regardless of the type of connection	0,75
c) with a complex cross grid with single-bolt connections according to Fig. 9*, e	0,7
10. Compressed elements from single angles, attached by one flange (for unequal angles only by a smaller flange), with the exception of the structural elements indicated in pos. 9 of this table, braces according to Fig. 9*, b, attached directly to the chords with welds or two or more bolts placed along the angle, and flat trusses from single angles	0,75
11. Base plates made of steel with a yield strength of up to 285 MPa (2900 kgf/cm2), bearing a static load, thickness, mm:
	1,2
b) over 40 to 60	1,15
c) over 60 to 80	1,1
Notes: 1. Operating conditions coefficients g with 1 should not be taken into account simultaneously when calculating. 2. Coefficients of operating conditions, given respectively in pos. 1 and 6, in; 1 and 7; 1 and 8; 2 and 7; 2 and 8,a; 3 and 6, c, should be taken into account simultaneously in the calculation. 3. Operating conditions coefficients given in pos. 3; 4; 6, a, c; 7; 8; 9 and 10, as well as in pos. 5 and 6, b (except for butt welded joints), the considered elements should not be taken into account when calculating connections. 4. In cases not specified in these standards, the formulas should take g c = 1.

5. CALCULATION OF ELEMENTS OF STEEL STRUCTURES FOR AXIAL FORCES AND BENDING

CENTRALLY EXTENSION AND CENTRALLY COMPRESSED ELEMENTS

5.1. Calculation of the strength of elements subject to central tension or compression by force N except those specified in clause 5.2, should be performed according to the formula

Calculation of the strength of sections in places of fastening of tensile elements from single angles, attached to one flange with bolts, should be performed according to formulas (5) and (6). In this case, the value g with in formula (6) should be taken according to adj. 4* of these standards.

5.2. Calculation of the strength of tensile steel structural elements with the ratio R u/g u > Ry, the operation of which is possible even after the metal reaches the yield point, should be carried out according to the formula

5.3. Calculation of stability of solid-wall elements subject to central compression by force N, should be performed according to the formula

Values j

at 0 £2.5

; (8)

at 2.5 £4.5

at > 4,5

. (10)

Numerical values j are given in table. 72.

5.4*. Rods made from single angles must be designed for central compression in accordance with the requirements set out in clause 5.3. When determining the flexibility of these rods, the radius of gyration of the angle section i and effective length lef should be taken according to paragraphs. 6.1 – 6.7.

When calculating the chords and lattice elements of spatial structures from single corners, the requirements of clause 15.10* of these standards should be met.

5.5. Compressed elements with solid walls of an open U-shaped section with l x 3l y , Where l x And l y – calculated flexibility of the element in planes perpendicular to the axes, respectively x– x And y -y (Fig. 1), it is recommended to strengthen it with slats or gratings, and the requirements of paragraphs must be met. 5.6 and 5.8*.

In the absence of strips or gratings, such elements, in addition to calculations using formula (7), should be checked for stability during flexural-torsional mode of buckling according to the formula

Where j y – buckling coefficient, calculated according to the requirements of clause 5.3;

With

(12)

Where ;

a = a x/ h – relative distance between the center of gravity and the center of bending.

J w – sectorial moment of inertia of the section;

b i And t i – respectively the width and thickness of the rectangular elements making up the section.

For the section shown in Fig. 1, a, values And a must be determined by the formulas:

Where b = b/h.

5.6. For composite compressed rods, the branches of which are connected by strips or gratings, the coefficient j relative to the free axis (perpendicular to the plane of the slats or gratings) should be determined by formulas (8) – (10) with replacement in them by ef. Meaning ef should be determined depending on the values lef given in table. 7.

Table 7

Type			Scheme			Flexibility given lef composite through-section bars
sections			sections			with slats at		with bars
						J s l /( J b b) 5	J s l /( J b b) ³ 5
1						(14)	(17)	(20)
2						(15)	(18)	(21)
3						(16)	(19)	(22)
Designations adopted in table. 7:
b				– distance between the axes of the branches;
l				– distance between the centers of the planks;
l				– the greatest flexibility of the entire rod;
l 1, l 2, l 3				– flexibility of individual branches when bending them in planes perpendicular to the axes, respectively 1 – 1 , 2 – 2 and 3 – 3, in areas between welded strips (in the clear) or between the centers of the outer bolts;
A				– cross-sectional area of ​​the entire rod;
A d1 and A d2				– cross-sectional area of ​​the grid braces (with a cross grid – two braces) lying in planes perpendicular to the axes, respectively 1 – 1 And 2 – 2;
A d				– cross-sectional area of ​​the lattice brace (with a cross lattice – two braces) lying in the plane of one face (for a triangular equilateral rod);
a 1 And a 2				– coefficients determined by the formula
Where				– dimensions determined from Fig. 2;
	n, n 1, n 2, n 3			– coefficients determined accordingly by formulas;
Here			J b1 And J b3		– moments of inertia of the sections of the branches relative to the axes, respectively 1 – 1 and 3 – 3 (for sections of types 1 and 3);
			J b1 And J b2		– the same, two corners relative to the axes, respectively 1 – 1 and 2 – 2 (for section type 2);
					– moment of inertia of the section of one bar relative to its own axis x– x (Fig. 3);
			Js1 And J s2		– moments of inertia of the section of one of the strips lying in planes perpendicular to the axes, respectively 1 – 1 and 2 – 2 (for section type 2).

In composite rods with lattices, in addition to calculating the stability of the rod as a whole, the stability of individual branches in the areas between the nodes should be checked.

Flexibility of individual branches l 1 , l 2 And l 3 in the area between the slats there should be no more than 40.

If there is a solid sheet in one of the planes instead of slats (Fig. 1, b, V) the flexibility of the branch should be calculated by the radius of gyration of the half-section relative to its axis perpendicular to the plane of the slats.

In composite bars with lattices, the flexibility of individual branches between nodes should be no more than 80 and should not exceed the given flexibility lef the rod as a whole. It is allowed to accept higher values ​​of branch flexibility, but not more than 120, provided that the calculation of such rods is carried out according to a deformed scheme.

5.7. Calculation of composite elements made of angles, channels, etc., connected tightly or through spacers, should be performed as solid-walled, provided that the largest distances in the areas between welded strips (in the clear) or between the centers of the outer bolts do not exceed:

for compressed elements 40 i

for tensile elements 80 i

Here the radius of inertia i corner or channel should be taken for T- or I-sections relative to an axis parallel to the plane of the spacers, and for cross sections – minimal.

In this case, at least two spacers should be installed within the length of the compressed element.

5.8*. Calculation of connecting elements (planks, gratings) of compressed composite rods should be carried out for a conditional transverse force Qfic, taken to be constant along the entire length of the rod and determined by the formula

Qfic = 7,15 × 10 -6 (2330 – E/Ry)N/j, (23)*

Where N – longitudinal force in the composite rod;

j – longitudinal bending coefficient accepted for a composite rod in the plane of the connecting elements.

Conditional shear force Qfic should be distributed:

if there are only connecting strips (grids), equally between the strips (grids) lying in planes perpendicular to the axis relative to which the stability is checked;

in the presence of a solid sheet and connecting strips (grids) – in half between the sheet and slats (lattices) lying in planes parallel to the sheet;

when calculating equilateral triangular composite rods, the conditional transverse force exerted on a system of connecting elements located in the same plane should be taken equal to 0.8 Qfic.

5.9. The calculation of connecting strips and their attachment (Fig. 3) should be performed as a calculation of elements of braceless trusses on:

force F, cutting bar, according to the formula

F = Q s l/b; (24)

moment M 1, bending the bar in its plane, according to the formula

M 1 = Q s l/2 (25)

Where Q s – conditional transverse force applied to the bar of one face.

5.10. The calculation of connecting lattices should be carried out as a calculation of truss lattices. When calculating the cross braces of a cross lattice with struts (Fig. 4), the additional force should be taken into account N ad, arising in each brace from compression of the belts and determined by the formula

(26)

Where N – force in one branch of the rod;

A – cross-sectional area of ​​one branch;

A d – cross-sectional area of ​​one brace;

a – coefficient determined by the formula

a = a l 2 /(a 3 =2b 3) (27)

Where a, l And b – dimensions shown in Fig. 4.

5.11. The calculation of rods intended to reduce the design length of compressed elements must be performed for a force equal to the conventional transverse force in the main compressed element, determined by formula (23)*.

BENDING ELEMENTS

5.12. Calculation of the strength of elements (except for beams with a flexible wall, with a perforated wall and crane beams) bent in one of the main planes should be performed according to the formula

(28)

Shear stress value t in sections of bent elements must satisfy the condition

(29)

If the wall is weakened by bolt holes, the values t in formula (29) should be multiplied by the coefficient a , determined by the formula

a = a/(a – d), (30)

Where a – hole pitch;

b – hole diameter.

5.13. To calculate the strength of the beam wall in places where the load is applied to the upper chord, as well as in the support sections of the beam that are not reinforced with stiffeners, the local stress should be determined s loc according to the formula

(31)

Where F – calculated value of load (force);

lef – conditional length of load distribution, determined depending on the support conditions; for the case of support according to Fig. 5.

lef = b + 2t f, (32)

Where t f – thickness of the upper chord of the beam, if the lower beam is welded (Fig. 5, A), or the distance from the outer edge of the flange to the beginning of the internal rounding of the wall, if the lower beam is rolled (Fig. 5, b).

5.14*. For beam walls calculated using formula (28), the following conditions must be met:

Where – normal stresses in the midplane of the wall, parallel to the axis of the beam;

s y – the same, perpendicular to the axis of the beam, including s loc , determined by formula (31);

t xy – tangential stress calculated using formula (29) taking into account formula (30).

Voltages s x And s y , taken in formula (33) with their own signs, as well as t xy should be determined at the same point in the beam.

5.15. Calculation of the stability of I-section beams that are bent in the plane of the wall and meet the requirements of paragraphs. 5.12 and 5.14*, should be performed according to the formula

Where W c – should be determined for a compressed belt;

j b – coefficient determined by adj. 7*.

When determining the value j b for the estimated length of the beam lef the distance between the points of fastening of the compressed belt from transverse displacements (nodes of longitudinal or transverse links, points of fastening of rigid flooring) should be taken; in the absence of connections lef = l(Where l – beam span) the design length of the cantilever should be taken as follows: lef = l in the absence of fastening the compressed belt at the end of the console in the horizontal plane (here l – console length); the distance between the fastening points of the compressed belt in the horizontal plane when fastening the belt at the end and along the length of the console.

5.16*. The stability of the beams does not need to be checked:

a) when transferring the load through a continuous rigid flooring, continuously supported by the compressed belt of the beam and securely connected to it (reinforced concrete slabs made of heavy, light and cellular concrete, flat and profiled metal flooring, corrugated steel, etc.);

b) in relation to the calculated length of the beam lef to the width of the compressed belt b, not exceeding the values ​​determined by the formulas in table. 8* for beams of symmetrical I-section and with a more developed compressed chord, for which the width of the tensioned chord is at least 0.75 of the width of the compressed chord.

Table 8*

Load application location	Largest values lef /b, for which stability calculations for rolled and welded beams are not required (at 1 £ h/b 6 and 15 £ b/t £35)
To the upper belt	(35)
To the lower belt	(36)
Regardless of the level of load application when calculating the beam section between braces or in pure bending	(37)
Designations adopted in table 8*: b And t – respectively the width and thickness of the compressed belt; h – distance (height) between the axes of the belt sheets. Notes: 1. For beams with chord connections on high-strength bolts, the values lef/b, obtained from the formulas in Table 8* should be multiplied by a factor of 1.2. 2. For beams with ratio b/t /t= 15.

The fastening of the compressed belt in the horizontal plane must be designed for actual or conditional lateral force. In this case, the conditional lateral force should be determined:

when fixed at individual points according to formula (23)*, in which j should be determined with flexibility l = lef/i(Here i – radius of inertia of the section of the compressed belt in the horizontal plane), and N should be calculated using the formula

N = (A f + 0,25A W)Ry; (37, a)

with continuous fastening according to the formula

qfic = 3Qfic/l, (37, b)

Where qfic – conditional transverse force per unit length of the beam chord;

Qfic – conditional transverse force, determined by formula (23)*, in which it should be taken j = 1, a N – determined by formula (37,a).

5.17. Calculation of the strength of elements bent in two main planes should be performed according to the formula

(38)

Where x And y – coordinates of the section point under consideration relative to the main axes.

In beams calculated using formula (38), the stress values ​​in the beam web should be checked using formulas (29) and (33) in the two main bending planes.

If the requirements of clause 5.16* are met, A checking the stability of beams bent in two planes is not required.

5.18*. Calculation of the strength of split beams of solid section made of steel with a yield strength of up to 530 MPa (5400 kgf/cm2), bearing a static load, subject to paragraphs. 5.19* – 5.21, 7.5 and 7.24 should be performed taking into account the development of plastic deformations according to the formulas

when bending in one of the main planes under tangential stresses t £0.9 R s(except for support sections)

(39)

when bending in two main planes under tangential stresses t £0.5 R s(except for support sections)

(40)

Here M, M x And M y – absolute values ​​of bending moments;

c 1 – coefficient determined by formulas (42) and (43);

c x And c y – coefficients accepted according to table. 66.

Calculation in the support section of beams (with M = 0; M x= 0 and M y= 0) should be performed according to the formula

In the presence of a zone of pure bending in formulas (39) and (40) instead of the coefficients c 1, c x And with y should be taken accordingly:

from 1m = 0,5(1+c); c xm = 0,5(1+c x); with ym = 0,5(1+c y).

With simultaneous action in the moment section M and shear force Q coefficient from 1 should be determined using the formulas:

at t £0.5 R s c 1 = c; (42)

at 0.5 R s t £0.9 R s c 1 = 1,05b c , (43)

Where (44)

Here With – coefficient accepted according to the table. 66;

t And h – wall thickness and height, respectively;

a – coefficient equal to a = 0.7 for an I-section bent in the plane of the wall; a = 0 – for other types of sections;

from 1 – a coefficient taken to be no less than one and no more than a coefficient With.

In order to optimize beams when calculating them taking into account the requirements of paragraphs. 5.20, 7.5, 7.24 and 13.1 coefficient values With, c x And with y in formulas (39) and (40) it is allowed to take less than the values ​​​​given in table. 66, but not less than 1.0.

If the wall is weakened by bolt holes, the shear stress values t should be multiplied by the coefficient determined by formula (30).

Official publication

STATE COMMITTEE OF THE USSR COUNCIL OF MINISTERS FOR CONSTRUCTION (GOSSTROY USSR)

UDC *27.9.012.61 (083.75)

Chapter SNiP 11-56-77 “Concrete and reinforced concrete structures of hydraulic structures” was developed by VNIIG named after. B. E. Vedeneev, Institute “Gndroproekt* named after. S. Ya. Zhuk of the Ministry of Energy of the USSR and Giprorechtrans of the Ministry of River Fleet of the RSFSR with the participation of GruzNIIEGS of the Ministry of Energy of the USSR. Soyuzmornniproekt Miimorflot, Giprovodchoea Ministry of Water Resources of the USSR and NIIZhB Gosstroy USSR

Chapter SNiP 11-56-77 “Concrete and reinforced concrete structures of hydraulic structures” was developed on the basis of chapter SNiP P-A.10-71 “Building structures and foundations. Basic design principles."

chapter SNiP N-I.14-69 “Concrete reinforced concrete structures of hydraulic structures. Design standards";

changes to the chapter of SNiP N-I.14-69, fine linen by resolution of the USSR State Construction Committee dated March 16, 1972 X* 42.

Editors -iizh. E. A. TROITSKIP (Gosstroy USSR), Ph.D. tech. Sciences A. V. SHVETSOV (VNIIG named after B. E. Vedeneev. Ministry of Energy of the USSR), researcher. S. F. LIVES AND I (Gndroproekt named after S. Ya. Zhuk of the USSR Ministry of Energy), and NNG. S. P. SHIPILOVA (Giprorechtrans Ministry of River Fleet of the RSFSR).

N meter at.-mormat., II km. - I.*-77

© Stroykzdat, 1977

State Committee of the Council of Ministers of the USSR for Construction Affairs (Gosstroy USSR)

I. GENERAL PROVISIONS

1.1. The standards of this chapter must be observed when designing load-bearing concrete and reinforced concrete structures of hydraulic structures that are constantly or periodically exposed to the aquatic environment.

Notes: !. The standards of this chapter should not be applied when designing concrete and reinforced concrete structures of bridges, transport tunnels, as well as pipes located under embankments of roads and railways.

2. Concrete and reinforced concrete structures that are not exposed to the aquatic environment should be designed in accordance with the requirements of chapter SNiP II-2I-75 “Concrete and reinforced concrete structures”.

1.2. When designing concrete and reinforced concrete structures of hydraulic structures, it is necessary to be guided by the chapters of SNiP and other all-Union regulatory documents regulating the requirements for materials, rules for construction work, special construction conditions in seismic areas, in the Northern construction-climatic zone and in the zone of distribution of subsidence soils, and also requirements for protecting structures from corrosion in the presence of aggressive environments.

1.3. When designing, it is necessary to provide for such concrete and reinforced concrete structures (monolithic, prefabricated monolithic, prefabricated, including prestressed), the use of which ensures the industrialization and mechanization of construction work, reducing material consumption, labor intensity, reducing the duration and reducing the cost of construction.

1.4. Types of structures, the main dimensions of their elements, as well as the degree of saturation of reinforced concrete structures with reinforcement should

We are accepted on the basis of a comparison of the technical and economic indicators of the options. In this case, the chosen option must provide optimal performance. reliability, durability and cost-effectiveness of the structure.

1.5. The designs of units and connections of prefabricated elements must ensure reliable transmission of forces, the strength of the elements themselves in the joint area, the connection of concrete additionally laid in the joint with the concrete of the structure, as well as rigidity, water resistance (in some cases, soil permeability) and durability of the connections.

1.6. When designing new designs of hydraulic structures that have not been sufficiently tested in design and construction practice, for complex conditions of static and dynamic operation of structures, when the nature of their stressed and deformed state cannot be determined with the necessary reliability by calculation, experimental studies should be carried out.

1.7. Projects should include technological and design measures. helping to increase the water resistance and frost resistance of concrete and reduce back pressure: laying concrete with increased water resistance and frost resistance on the side of the pressure face and external surfaces (especially in the area of ​​​​variable water levels); the use of special surface-active additives to concrete (air-entraining, plasticizing, etc.); waterproofing and thermal insulation of external surfaces of structures; compression of concrete from pressure faces or external surfaces of structures experiencing tension from operational loads.

1.8. When designing hydraulic structures, it is necessary to provide for

the ice coverage of their construction, the system for cutting them with temporary seams and the mode of their closure, ensuring the most efficient operation of structures during the construction and operational periods.

BASIC CALCULATION REQUIREMENTS

1.9. Concrete and reinforced concrete structures must satisfy the calculation requirements for load-bearing capacity (limit states of the first group) - for all combinations of loads and impacts, and for suitability for normal operation (limit states of the second group) - only for the main combination of loads and impacts.

Concrete structures should be calculated:

in terms of bearing capacity - for strength with checking the stability of the position and shape of the structure;

for cracking - in accordance with Section 5 of these standards.

Reinforced concrete structures should be calculated:

in terms of bearing capacity - for strength with checking the stability of the position and shape of the structure, as well as for the endurance of structures under the influence of repeated loads;

by deformations - in cases where the magnitude of movements may limit the possibility of normal operation of the structure or the mechanisms located on it;

on the formation of cracks - in cases where, under the conditions of normal operation of the structure, the formation of cracks is not allowed, or on the opening of cracks.

1.10. Concrete and reinforced concrete structures in which the conditions for the onset of a limit state cannot be expressed in terms of forces in the section (gravity and arch dams, buttresses, thick slabs, beam-walls, etc.) should be calculated using the methods of continuum mechanics, taking into account, if necessary, inelastic deformations and cracks in concrete.

In some cases, the calculation of the above structures can be carried out using the strength of materials method in accordance with the design standards for certain types of hydraulic structures.

For concrete structures, compressive stresses under design loads should not exceed the values ​​of the corresponding design resistances of concrete; for reinforced concrete structures, compressive stresses in concrete should not exceed the calculation

concrete resistance to compression, and tensile forces in the section at stresses in concrete exceeding the value of its design resistance must be fully absorbed by the reinforcement, if failure of the tensioned concrete zone can lead to loss of the bearing capacity of the element; in this case, coefficients should be taken in accordance with paragraphs. 1.14, 2.12 and 2.18 of these standards.

1.11. Standard loads are determined by calculation in accordance with current regulatory documents, and, if necessary, based on the results of theoretical and experimental studies.

Combinations of loads and impacts, as well as overload factors l must be adopted in accordance with chapter SNiP II-50-74 “River hydraulic structures. Basic principles of design".

When calculating structures for endurance and for limit states of the second group, an overload factor of one should be taken.

1.12. Deformations of reinforced concrete structures and their elements, determined taking into account the long-term action of loads, must not exceed the values ​​​​established by the project, based on the requirements of normal operation of equipment and mechanisms.

Calculation of deformations of structures and their elements of hydraulic structures may not be carried out if, based on operating experience of similar structures, it is established that the rigidity of these structures and their elements is sufficient to ensure normal operation of the structure being designed.

1.13. When calculating prefabricated structures for the forces arising during their lifting, transportation and installation, the load from the element’s own weight should be included in the calculation with a dynamic coefficient equal to

1.3, while the overload coefficient to its own weight is taken equal to unity.

With proper justification, the dynamism coefficient can be taken to be more

1.3, but not more than 1.5.

1.14. In calculations of concrete and reinforced concrete structures of hydraulic structures, including those calculated in accordance with art. 1.10 of these standards, it is necessary to take into account the reliability factors A i n load combinations p s. the values ​​of which should be taken according to clause 3.2 of chapter SNiP 11-50-74.

1.15. The magnitude of water back pressure in the design sections of elements should be determined taking into account actual operating conditions

structures during the operational period, as well as taking into account design and technological measures (clause 1.7 of these

standards) that help increase the water resistance of concrete and reduce back pressure.

In elements of pressure and underwater concrete and reinforced concrete structures of hydraulic structures, calculated in accordance with clause 1.10 of these standards, water back pressure is taken into account as a volumetric force.

In the remaining elements, water back pressure is taken into account as a tensile force applied in the design section under consideration.

Water back pressure is taken into account both when calculating sections coinciding with concreting seams and monolithic sections.

1.16. When calculating the strength of centrally-tensioned and eccentrically-tensioned elements with an unambiguous stress diagram and calculating the strength of sections of reinforced concrete elements inclined to the longitudinal axis of the element, as well as when calculating reinforced concrete elements for the formation of cracks, the back pressure should be assumed to vary according to a linear law within the entire height of the section.

In sections of bending, eccentrically compressed and eccentrically tensile elements with a two-digit stress diagram calculated by strength without taking into account the work of concrete in the tensioned section zone, the back pressure of water should be taken into account within the tensioned zone of the section in the form of total hydrostatic pressure on the side of the tensile face and not take into account within the compressed zone of the section.

In sections of elements with an unambiguous diagram of compressive stresses, back pressure is not taken into account.

The height of the compressed zone of the concrete section is determined based on the hypothesis of flat sections; in this case, in non-crack-resistant elements, the work of tensile concrete is not taken into account, and the shape of the concrete stress diagram in the compressed section zone is assumed to be triangular.

In elements with a cross-section of complex configuration, in elements using structural and technological measures and in elements calculated in accordance with clause 1.10 of these standards, the values ​​of water back pressure forces should be determined based on the results of experimental studies or filtration calculations.

Note. The type of stress state of the element is established based on the hypothesis of flat sections without taking into account the force of water backpressure.

1.17. When determining forces in statically indeterminate reinforced concrete structures caused by temperature effects or settlement of supports, as well as when determining reactive soil pressure, the rigidity of elements should be determined taking into account the formation of cracks in them and the creep of concrete, the requirements for which are provided for in paragraphs. 4.6 and 4.7 of these standards.

In preliminary calculations, it is allowed to take the bending and tensile rigidity of non-crack-resistant elements equal to 0.4 of the bending and tensile rigidity. determined at the initial modulus of elasticity of concrete.

Note. Non-crack-resistant elements include elements calculated by the size of crack opening; to crack-resistant - calculated according to the formation of cracks.

1.18. Calculation of structural elements for endurance must be carried out with a number of load change cycles of 2-10® or more over the entire design life of the structure (flow parts of hydraulic units, spillways, water tank slabs, sub-generator structures, etc.).

1.19. When designing prestressed reinforced concrete structures of hydraulic structures, the requirements of chapter SNiP P-21-75 should be met and the coefficients adopted in these standards should be taken into account.

1.20. When designing prestressed massive structures anchored into the base, along with their calculations, experimental studies should be carried out to determine the load-bearing capacity of anchor devices, stress relaxation values ​​in concrete and anchors, as well as to prescribe measures to protect anchors from corrosion. The design must provide for the possibility of re-tensioning the anchors or replacing them, as well as conducting control observations of the condition of the anchors and concrete.

2. MATERIALS FOR CONCRETE AND REINFORCED CONCRETE STRUCTURES

2.1. For concrete and reinforced concrete structures of hydraulic structures, concrete should be provided that meets the requirements of these standards, as well as the requirements of the relevant GOSTs.

2.2. When designing concrete and reinforced concrete structures of hydraulic structures, depending on their type and design

During the work, the required concrete characteristics, called design grades, are assigned.

Projects must include heavy concrete, the design grades of which must be assigned according to the following criteria:

a) by axial compression strength (cube strength), which is taken to be the axial compression resistance of a reference sample - a cube, tested in accordance with the requirements of the relevant GOSTs. This characteristic is the main one and must be indicated in projects in all cases based on structural calculations. Projects must provide the following grades of concrete in terms of compressive strength (abbreviated as “design grades>): M 75, M 100, M 150, M 200. M 250, M 300. M 350, M 400, M 450, M 500, M 600;

b) by axial tensile strength, which is taken to be the axial tensile resistance of control samples tested in accordance with GOST standards. This characteristic should be assigned in cases where it is of primary importance and is controlled in production, namely, when the performance qualities of the structure or its elements are determined by the work of tensile concrete or the formation of cracks in structural elements is not allowed. Projects must include the following grades of concrete in terms of axial tensile strength: R10, R15, R20, R25, RZO, R35;

c) by frost resistance, which is taken to be the number of cycles of alternating freezing and thawing of samples tested in accordance with the requirements of GOST standards; this characteristic is assigned according to the relevant GOSTs depending on climatic conditions and the number of design cycles of alternating freezing and thawing during the year (according to long-term observations) taking into account operating conditions. Projects must include the following grades of concrete for frost resistance: Mrz 50, Mrz 75, Mrz 100, Mrz 150, Mrz 200, Mrz 300, Mrz 400, Mrz 500;

d) by water resistance, which is taken to be the highest water pressure at which water infiltration is not yet observed when testing samples in accordance with the requirements of GOSTs. This characteristic is assigned depending on the pressure gradient, defined as the ratio of the maximum pressure in meters to the thickness of the cone

structures in meters. Projects must include the following grades of concrete for water resistance: B2, B4, B6, B8, B10, B12. In non-crack-resistant pressure reinforced concrete structures and in non-crack-resistant non-pressure structures of offshore structures, the design grade of concrete for water resistance must be at least B4.

2.3. For massive concrete structures with a concrete volume of more than 1 million m 1 in the project, it is allowed to establish intermediate values ​​of the standard resistance of concrete, which will correspond to the gradation of grades for compressive strength that differs from the gradation of grades for compressive strength established in paragraph 2.2 of these standards.

2.4. Concrete structures of hydraulic structures should be subject to additional requirements established in the project and confirmed by experimental studies for:

extreme elongation;

resistance to aggressive water;

absence of harmful interaction between cement alkalis and aggregates;

resistance to abrasion by flow of water with sediment and suspended sediments;

resistance against cavitation;

chemical exposure to various cargoes;

heat generation during concrete hardening.

2.5. The hardening period (age) of concrete, corresponding to its design grades for compressive strength, axial tensile strength and water resistance, is usually accepted for the structures of river hydraulic structures 180 days, for prefabricated and monolithic structures of marine and prefabricated structures of river transport structures 28 days . The curing period (age) of concrete corresponding to its design grade for frost resistance is assumed to be 28 days.

If the timing of the actual loading of structures, methods of their construction, concrete hardening conditions, type and quality of cement used are known, it is allowed to set the design grade of concrete at a different age.

For prefabricated structures, including prestressed structures, the tempering strength of concrete should be taken as less than 70% of the strength of the corresponding design grade.

2.6. For reinforced concrete elements made of heavy concrete, designed for the action of repeated loads, and reinforced concrete compressed elements of rod structures (embankments such as overpasses on piles, shell piles, etc.) it is necessary

use a design grade of concrete not lower than M 200.

2.7. For prestressed elements, the design grades of concrete for compressive strength should be adopted:

not less than M 200 - for structures with rod reinforcement;

not less than M 250 - for structures with high-strength reinforcing wire;

not less than M 400 - for elements immersed in the ground by driving or vibrating.

2.8. To embed joints of elements of prefabricated structures, which during operation may be exposed to negative temperatures of outside air or aggressive water, concrete of the design grades should be used for frost resistance and water resistance not lower than the accepted elements being joined.

2.9. It is necessary to provide for the widespread use of surfactant additives (SDB, SNV, etc.). as well as the use of fly ash from thermal power plants and other finely dispersed additives that meet the requirements of the relevant regulations as an active mineral additive

documents for the preparation of concrete and mortars.

Note. In areas of structures subject to alternating freezing and thawing, the use of fly ash or other fine mineral additives to concrete is not permitted.

2.10. If, for technical and economic reasons, it is advisable to reduce the load from the dead weight of the structure, it is allowed to use concrete on porous aggregates, the design grades of which are adopted in accordance with Chapter SNiP 11-21-75.

STANDARD AND DESIGN CHARACTERISTICS OF CONCRETE

2.11. The values ​​of the standard and design resistances of concrete, depending on the design grades of concrete for compressive strength and axial tensile strength, should be taken according to table. 1.

2.12. The coefficients of concrete operating conditions for calculating structures based on the limit states of the first group should be taken according to table. 2.

When calculating according to the limit states of the second group, the coefficient of concrete operating conditions is taken equal to unity, for ns-

Table 1

Vmh concrete resistance

Design grade of heavy concrete	standard resistances: design resistances for limit states of the second group, kgf/cm 1		calculated resistances for limit states of the first group, kgf/cm"
	axial compression (primary strength) Jpr "Y"r and	axial tension	axial compression (strength) I V p	axial tension *9
		As strong as a hedgehog
	By tensile strength

Note. Provision of the values ​​of standard resistances indicated in table. 1. is set equal to 0.95 (with a base coefficient of variation of 0.135), except for massive hydraulic structures: gravity. arched, mass-buttress dams, etc.. for which the provision of standard resistance is set to 0.9 (with a basic coefficient of variation of 0.17).

inclusion of calculations under the action of a repeatedly repeated load.

table 2

2.13. Design resistance of concrete when calculating reinforced concrete structures for endurance /? P r and R r are calculated by multiplying the corresponding values ​​of concrete resistance /?pr n /? p on the coefficient of operating conditions of the TV. accepted according to the table 3 of these standards.

2.14. The standard resistance of concrete under all-round compression R& should be determined by the formula

**„, + * d-o,) a and (1)

where A is the coefficient adopted based on the results of experimental studies; in their absence, for concrete of design grades M 200, M 250, M 300, M 350, coefficient A should be determined by the formula

oj - the smallest absolute value of the principal stress, kgf/cm g; ag is the coefficient of effective porosity, determined by experimental studies;

Design resistances are determined according to table. 1 depending on the value by interpolation.

2.15. The value of the initial modulus of elasticity of concrete in compression and tension £ 0 should be taken according to table. 4.

The initial transverse deformation coefficient of concrete c is assumed to be equal to 0.15, and the shear modulus of concrete G is equal to 0.4 of the corresponding values ​​£в-

Table 3

where and a byaks are respectively the smallest and the greatest stresses in concrete within the limits

load change cycle.

Note. The values ​​of the m61 coefficient for concrete, the grade of which is established at the age of 28 days, are adopted in accordance with chapter SNiP 11-21-75.

Table 4

Note. Table values 4 initial modulus of elasticity of concrete for class 1 structures should be clarified based on the results of experimental studies.

The volumetric weight of heavy concrete, in the absence of experimental data, can be taken equal to 2.3-2.5 t/m*.

FITTINGS

2.16. To reinforce reinforced concrete structures of hydraulic structures, reinforcement should be used in accordance with chapters of SNiP P-21-75. SNiP 11-28-73 protection of building structures from corrosion”, current GOST or technical specifications approved in the prescribed manner.

STANDARD AND DESIGN CHARACTERISTICS OF FITTINGS

2.17. Values ​​of standard and design resistances of the main types of reinforcement used in reinforced concrete structures

Table 5

	Regulatory	Design resistance of reinforcement for limit states of the first group, kgf/cm*
	resistance	stretching
Type and class of fittings	Rg and calculated tensile strength for limit states of the second group *a 11 - kgf/cm*	longitudinal, transverse (clamps and bent rods) when calculating inclined sections at this point, I bend the minimum moment “a”	transverse (clamps and BENT rods) when calculating inclined sections and the action of p- pepper si-*a-x
Bar reinforcement class:
Wire fittings class:
B-I diameter
VR-I with a diameter of 3-4 mm
VR-I with a diameter of 5 mm

* In welded frames for clamps made of class A IM reinforcement. the diameter of which is less than */" the diameter of the longitudinal rods, the value of /?".* is taken equal to 2400 kgf/cm*.

Notes: I. The values ​​of L forged are given for the case of using wire reinforcement of classes B-I and Bp I in ayashma frames.

2. In the absence of adhesion between the reinforcement and the concrete, c is taken equal to zero.

3. Reinforcing steel of classes A-IV and A-V is allowed under. change only for prestressed structures

hydraulic structures, depending on the class of reinforcement, should be taken according to table. 5.

Regulatory and design characteristics of other types of fittings must be taken according to the instructions of the chapter of SNiP 11-21-75.

2.18. Coefficients of operating conditions for non-prestressed reinforcement should be taken according to table. 6 of these standards, and prestressed reinforcement according to table. 24 chapters of SNiP 11-21-75.

Table b

Note. In the presence of several factors. operating simultaneously, the product of the corresponding operating conditions coefficients is introduced into the calculation.

The coefficient of operating conditions of the reinforcement for calculations based on the limit states of the second group is taken equal to unity.

2.19. The design resistance of non-prestressed tensile rod reinforcement R when calculating reinforced concrete structures for endurance should be determined by the formula

/? in ■ t a, R t , (3)

where t w\ is the coefficient of working conditions, calculated by the formula

where is the co-factor, taking into account the class of reinforcement, adopted according to the table.

k i - coefficient taking into account the diameter of the reinforcement, taken according to the table. 8;

k c - coefficient taking into account the type of welded joint, adopted according to the table. 9;

p, = cycle asymmetry coefficient,

where a *i*n and a, μs are the minimum and maximum stresses in tensile reinforcement, respectively.

Tensile reinforcement for endurance is not calculated if the value of the coefficient t a1, determined by formula (4), is greater than one.

Table 7

Reinforcement class

Coefficient value * in

Table 8

Diameter of fittings, mm
Coefficient value

Note. For intermediate values ​​of the reinforcement diameter, the value of the coefficient »d is determined by interpolation.

Table 9

Note. For reinforcement that does not have welded butt joints, the value of k e is taken equal to one.

2.20. The design resistance of reinforcement when calculating the endurance of prestressed structures is determined in accordance with chapter SNiP 11-21-75.

2.21. The values ​​of the modulus of elasticity of non-prestressed reinforcement and prestressed rod reinforcement are taken according to table. 10 of these standards; The values ​​of the elastic modulus of reinforcement of other types are taken from the table. Chapter 29 of SNiP P-21-75.

2.22. When calculating reinforced concrete structures for endurance, inelastic deformations in the compressed zone of concrete should be taken into account

Table 10

by reducing the elastic modulus of concrete, taking the coefficients of reduction of reinforcement to concrete n" according to Table 11.

Table II

Design grade of concrete
Reduction factor n"

3. CALCULATION OF ELEMENTS

CONCRETE AND REINFORCED CONCRETE STRUCTURES ACCORDING TO THE LIMITING STATES OF THE FIRST GROUP

CALCULATION OF CONCRETE ELEMENTS BY STRENGTH

3.1. Calculation of the strength of elements of concrete structures should be carried out for sections. normal to their longitudinal axis, and elements calculated in accordance with clause 1.10 of these standards - for areas of action of principal stresses.

Depending on the operating conditions of the elements, they are calculated both without taking into account and taking into account the resistance of concrete in the tensile section zone.

Without taking into account the resistance of concrete in the tensile section zone, eccentrically compressed elements are calculated, in which, according to operating conditions, the formation of cracks is allowed.

Taking into account the resistance of concrete in the tensile section zone, all bending elements are calculated, as well as centrically compressed elements in which, according to operating conditions, the formation of cracks is not allowed.

3.2. Concrete structures, the strength of which is determined by the strength of the concrete

drawn section zone are allowed for use if the formation of cracks in them does not lead to destruction, unacceptable deformations or a violation of the waterproofness of the structure. In this case, it is mandatory to check the crack resistance of elements of such structures, taking into account temperature and humidity influences in accordance with Section 5 of these standards.

3.3. Calculation of externally compressed concrete elements without taking into account the resistance of concrete in the tensile section zone is carried out based on the resistance of concrete to compression, which is conventionally characterized by stresses equal to /? etc. multiplied by the coefficients of concrete operating conditions, those.

3.4. The influence of the deflection of centrically compressed concrete elements on their load-bearing capacity is taken into account by multiplying the magnitude of the maximum force perceived by the section by the coefficient<р, принимаемый по табл. 12.

Table 12

Designations adopted in table. 12:

U-calculated length of the element;

b - the smallest size of a straight section; r - the smallest radius of gyration of the section.

When calculating flexible concrete elements at -->10 or ->35, it should be taken into account

the influence of long-term load on the load-bearing capacity of the structure in accordance with chapter SNiP 11-21-75 with the introduction of design coefficients adopted in these standards.

Bendable elements

3.5. Calculation of concrete bending elements should be made according to the formula

/k M< т А те /?„ 1Г Т, (5)

where t A is a coefficient determined depending on the section height according to the table. 13;

moment of resistance for the tensioned face of the section, determined with

Table 13

taking into account the inelastic properties of concrete according to the formula B\-y1Gr. (6)

where y is a coefficient that takes into account the influence of plastic deformations of concrete depending on the shape and ratio of cross-sectional dimensions, accepted according to lril. 1;

Nop is the moment of resistance for the tensile face of the section, determined as for an elastic material.

For sections of more complex shapes, in contrast to the data given in the appendix. 1, W r should be determined in accordance with clause 3.5 of chapter SNiP 11-21-75.

Eccentrically compressed elements

3.6. Eccentrically compressed concrete elements that are not exposed to aggressive water and do not withstand water pressure should be calculated without taking into account the resistance of concrete in the tensioned section zone, assuming

Rice. 1. Scheme of forces and stress diagram in a section normal to the longitudinal axis of an ancestrally compressed concrete element, calculated without taking into account the resistance of concrete in the tensile zone in -■ assuming a rectangular diagram of compressive stresses; b - ■ assuming a triangular diagram of compressive stresses

Zhenin rectangular diagram of compressive stresses (Fig. 1, a) according to the formula

k n n c N /P<5 Рпр Рб>AND)

where Гс is the cross-sectional area of ​​the compressed zone of concrete, determined from the condition that its center of gravity coincides with the point of application of the resultant external forces.

Note. In sections calculated using formula (7), the value of eccentricity e 0 of the design force relative to the center of gravity of the section should not exceed 0.9 of the distance y from the center of gravity of the section to its most stressed edge.

3.7. Viscentrically compressed elements of concrete structures exposed to aggressive pressure or susceptible to water pressure, without taking into account the resistance of the tensile section zone, should be calculated assuming a triangular diagram of compressive stresses (Fig. 1.6); in this case, the edge compressive stress c must satisfy the condition

<р т<5 /? П р ° < 8)

Rectangular sections are calculated using the formula

3 M0.5A-,o) S " Pm

3.8. When taking into account the resistance of the tensile section zone, centrically compressed elements of concrete structures should be calculated from the condition of limiting the magnitude of marginal tensile and compressive stresses using the formulas:

*vp e y’)<* Y «а "Ь Яр: O0)

"s (°.v -■ +-7)< Ф «в. О»

where and W c are the moments of resistance, respectively, for the stretched and compressed face of the section.

Using formula (11), it is also possible to calculate eccentrically compressed concrete structures with an unambiguous stress diagram.

CALCULATION OF REINFORCED CONCRETE ELEMENTS BY STRENGTH

3.9. Calculation of the strength of elements of reinforced concrete structures should be carried out for sections that are symmetrical relative to the plane of the acting forces M. N and Q, normal to their longitudinal axis, as well as for sections inclined to it in the most dangerous direction.

3.10. When installing reinforcement elements of different types and classes in a section, it is included in the strength calculation with the corresponding design resistances.

3.11. Calculation of elements for torsion with bending and for local action of loads (local compression, pushing, tearing and calculation of embedded parts) can be carried out in accordance with the methodology set out in chapter SNiP P-21-75, taking into account the coefficients adopted in these standards.

CALCULATION BY STRENGTH OF SECTIONS NORMAL TO THE LONGITUDINAL AXIS OF THE ELEMENT

3.12. The determination of the limiting forces in the section normal to the longitudinal axis of the element should be made under the assumption that the tensile zone of concrete has failed, conditionally assuming the stresses in the compressed zone to be distributed along a rectangular diagram and equal to motfnp. and the stresses in the reinforcement are no more than t l I a and t «/? a.s, respectively, for tensile and compressed reinforcement.

3.13. For bent, eccentrically compressed or eccentrically stretched elements with a large eccentricity, the calculation of sections normal to the longitudinal axis of the element, when the external force acts in the plane of the symmetry axis of the section and the reinforcement is concentrated at the edges of the element perpendicular to the specified plane, must be carried out depending on the ratio between the relative height of the compressed zone £=

Determined from the equilibrium condition, and

boundary value of the relative height of the compressed zone Ir. in which the limiting state of the element occurs simultaneously with the achievement of stress in the tensile reinforcement. equal to the calculated resistance m a R t .

Reinforced concrete elements that are bent and eccentrically stretched with large eccentricities, as a rule, must satisfy the condition For elements, sim.

metric relative to the plane of action of the moment and normal force, reinforced with non-prestressing reinforcement, the boundary values ​​|i should be taken according to table. 14.

Table 14

3.14. If the height of the compressed zone, determined without taking into account the compressed reinforcement, is less than 2a", then the compressed reinforcement is not taken into account in the calculation.

Bendable elements

3.15. Calculation of bendable reinforced concrete elements (Fig. 2), subject to the conditions of clause 3.13 of these standards, should be made according to the formulas:

k l p s M ^ /i$ R a r S& 4* i? a I a> c S*; (12)

Rice. 2. Scheme of forces and stress diagram in the section normal to the longitudinal axis of the bending reinforced concrete element, when calculating its strength

3.16. Calculation of bendable elements of rectangular cross-section should be made:

at £^£i according to the formulas:

p s M< те Я„р А х (А 0 - 0.5 х) +

T,/?, e ^(A,-a"); (14)

/ya and/?| - I| I a _ c fj * yage Rnp A x\ (15

for £>£« according to formula (15). taking r «=» «ъпЛо-

Occentrically compressed elements

3.17. Calculation of eccentrically compressed reinforced concrete elements (Fig. 3) at £<|я следует производить по формулам:

l with N e< т 6 R„ ? Se -f т» Я а с S* ; (16)

l s ^ “ t 6 I pr Fa -1- /i, I a- s F" - /i a Ya. F, . (17)

3.18. Calculation of eccentrically compressed elements of rectangular cross-section should be carried out:

for £^|i according to the formulas:

A and I with /V e

T,I,.c^ (A#-o"); (18)

A n p s LG ^tvYaprAdg + t* I a s F" - m t I. F a ; (19)

For £>|i - also according to formula (18) and the formulas:

*N l s A "- t b Yapr A lg ■+ t„ I a s F" - /I, a a I*; (20)

and for elements made of concrete grades higher than M 400, the calculation should be made in accordance with clause 3.20 of Chapter SNiP P-21-75, taking into account the design coefficients adopted in these standards.

3.19. Calculation of eccentrically compressed elements with flexibility ---^35, and elements of rectangular cross-section with -~^10 should be done

be carried out taking into account the deflection both in the plane of eccentricity of the longitudinal force and in the plane normal to it in accordance with paragraphs. 3.24. and 3.25 chapters of SNiP 11-21-75.

Centrally stretched elements

3.20. Calculation of centrally tensioned reinforced concrete elements should be made according to the formula

*.p with AG<т,Я в Г.. (22)

3.21. Calculation of the tensile strength of steel-reinforced concrete shells of round water pipelines under the action of uniform internal water pressure should be carried out according to the formula

A„p with AG<т, (Я./^ + ЛЛ,). (23)

where N is the force in the shell due to hydrostatic pressure, taking into account the hydrodynamic component;

F 0 and R are, respectively, the cross-sectional area and the calculated tensile strength of the steel shell, determined in accordance with chapter SNiP I-V.3-72 “Steel structures. Design standards

Eccentrically stretched elements

Rice. 3- Scheme of forces and diagram of stresses in a section normal to the longitudinal axis of an angularly compressed reinforced concrete element, when calculating its strength

3.22. Calculation of eccentrically tensioned reinforced concrete elements should be carried out: at small eccentricities, if the force N

applied between the resultant forces in the reinforcement (Fig. 4, a), according to the formulas:

^ fn t R t S t ‘, (25)

Rice. 4. Scheme of forces and stress diagram in the section normal to the longitudinal axis of a non-corroded reinforced concrete element, when calculating its strength

a - longitudinal force N is applied between the resultant forces in reinforcement A and L"; 6 - longitudinal force N is applied "within the distance between the resultant forces in reinforcement A and A"

at large eccentricities, if the force N is applied outside the distance between the resultant forces in the reinforcement (Fig. 4.6), according to the formulas:

^pr $$ + i*a I Shsh e ^a * (26)

*■ i e LG ■■ t w Yash F»~~ /i, R t t - fflj /?or ^v (27)

3.23. Calculation of eccentrically tensioned elements of rectangular cross-section should be carried out:

a) if the force N is applied between the resultant forces in the reinforcement, according to the formulas:

* > n c ArB

k a n c Ne"

b) if the force N is applied outside the distance between the resultant forces in the reinforcement:

at K£l according to the formulas:

kuncNt^m^Rap bх (A* - 0.5х) +

+ "b*sh.shK (30)

ku^N Ш| /? # Fj - m, e - nij /? pr b x (31) with 1>Ir no formula (31), taking x=.

CALCULATION BY SECTION STRENGTH. INCLINED TO THE LONGITUDINAL AXIS OF THE ELEMENT.

ON THE ACTION OF TRANSVERSE FORCE AND BENDING MOMENT

3.24. When calculating sections inclined to the longitudinal axis of the element, the condition * and l 0 must be met for the action of transverse force<}< 0,251^3 ЯпрЬ А, . (32)

where b is the minimum width of the element in section.

3.25. The calculation of transverse reinforcement is not carried out for sections of elements within which the condition is met

A, p e<г

where Qc is the lateral force perceived by the concrete of the compressed zone in an inclined section, determined by the formula<2 в = *Яр6АИ8р. (34)

gdr k - coefficient accepted by L - 0.5+ +25-

The relative height of the compressed zone of the section £ is determined by the formulas: for bending elements:

for eccentrically compressed and eccentrically stretched elements with large eccentricity

» Fa Yash, * f36.

BA* /? vr * BA,/?„р * 1 *

where the plus sign is taken for eccentrically compressed elements, and the minus sign for eccentrically stretched elements.

The angle between the inclined section and the longitudinal axis of element 0 is determined by the formula

teP--*7sr~t (37)

where M and Q are, respectively, the bending moment and shear force in the normal section passing through the end of the inclined section in the compressed zone.

For elements with a section height of 60 cm, the value of Qc, determined by formula (34), should be reduced by 1.2 times.

The value of tgP determined by formula (37) must satisfy the condition 1.5^ >W>0.5.

Note. For externally stretched elements with small eccentricities, one should take

3.26. For slab construction, spatially operating and on an elastic foundation, the calculation of transverse reinforcement is not carried out if the condition is met

3.27. Calculation of transverse reinforcement in inclined sections of elements of constant height (Fig. 5) should be made according to the formula

p with Q| % £ m t /? a _ x F\ 4- 2 m t /? a _ X G 0 sin o-tQe. (39)

Rice. 5. Scheme of forces in a section inclined to the longitudinal axis of a reinforced concrete element, when calculating its strength under the action of the load force a - the load is applied from the side of the restriated gr * “and chalked-t”; b - load applied from the side of the compressed memsite face

where Qi is the transverse force acting in the inclined section, i.e. the resultant of all transverse forces from the external load located on one side of the inclined section under consideration;

2m a R ax Fx and Smatfa-xfoSincc - the sum of the transverse forces perceived, respectively, by clamps and bent rods crossing the inclined section; a is the angle of inclination of the bent rods to the longitudinal axis of the element in an inclined section.

If an external load acts on an element from the side of its tensioned edge, as shown in Fig. 5, l, the calculated value of the transverse force Qi is determined by the formula Q.* co* p. (40)

where Q is the magnitude of the shear force in the support section;

Qo is the resultant of the external load acting on the element within the length of the projection of the inclined section c onto the longitudinal axis of the element;

W is the magnitude of the backpressure force acting in the inclined center, determined in accordance with clause 1.16 of these standards.

If an external load is applied to the compressed face of the element, as shown in Fig. 5.6, then the value Q 0 in formula (40) is not taken into account.

3.28. If the ratio of the calculated length of the element to its height is less than 5, the calculation of reinforced concrete elements under the action of transverse force should be carried out in accordance with clause 1.10 of these standards for main tensile stresses.

3.29. Calculation of bending and viscously-compressed elements of constant height, reinforced with clamps, can be carried out in accordance with paragraph 3.34 of Chapter SNNP 11-21-75, taking into account the design coefficients k„. p.s. gp (t i. adopted in these standards.

3.30. The distance between the transverse rods (clamps), between the end of the previous and the beginning of the next bend, as well as between the support and the end of the bend closest to the support, should be no more than the value u*ax. determined by the formula

M

3.31. For elements of variable height with an inclined stretched edge (Fig. 6), an additional transverse force Q* is introduced into the right side of formula (39). equal to the projection of the force in the longitudinal reinforcement located at the inclined face onto the normal to the axis of the element, determined by the formula

Р'с 6. Scheme of forces in an inclined section of a reinforced concrete structural element with an inclined stretched edge when calculating its strength under the action of transverse force

where M is the bending moment in the section normal to the longitudinal axis of the element, passing through the beginning of the inclined section in the tension zone; r is the distance from the resultant force in reinforcement A to the resultant force in the compressed zone of concrete in the same section;

O - angle of inclination of reinforcement A to the axis of the element.

Note. In cases where the height of the element decreases with increasing bending moment, the value

3.32. The calculation of a cantilever, the length of which /* is equal to or less than its height in the reference section L (short cantilever), should be carried out using the method of elasticity theory, as for a homogeneous isotropic body.

The tensile forces determined by calculation in the sections of the console must be fully absorbed by the reinforcement at stresses not exceeding the calculated resistance /? A. taking into account the coefficients adopted in these standards.

For cantilevers with a constant or variable section height at I*^2 m, it is allowed to take the diagram of the main tensile stresses in the support section in the form of a triangle with the orientation of the main stresses at an angle of 45° relative to the support section.

The cross-sectional area of ​​clamps or bends crossing the supporting section should be determined using the formulas:

P* » 0.71 F x , (44)

where P is the resultant external load; a is the distance from the resultant external load to the support section.

3.33. Calculation of sections inclined to the longitudinal axis of the element under the action of a bending moment should be made according to the formula

*in p s M^m t R t F t z + S t, R, F 0 z 0 +2 t l R t F x z x , (45)

where M is the moment of all external forces (taking into account backpressure) located on one side of the inclined section under consideration, relative to the axis. passing through the point of application of the resultant forces in the compressed zone and perpendicular to the plane of action of the moment; m M R x F a z, 2m x R x F o z 0 . Zm a R x F x z x - the sum of moments about the same axis, respectively, from the forces in the longitudinal reinforcement, in bent rods and stirrups crossing the stretched zone of the inclined section; g. g 0 . z x - force shoulders in the longitudinal reinforcement. in bent rods and clamps relative to the same axis (Fig. 7).

Rice. 7. Diagram of forces in a section inclined to the longitudinal axis of a reinforced concrete element, when calculating its strength under the action of a bending moment

The height of the compressed zone in an inclined section, measured normal to the longitudinal axis of the element, is determined in accordance with paragraphs. 3.14-3.23 of these standards.

Calculation using formula (45) should be made for sections tested for strength under the action of transverse forces, as well as:

in sections passing through points of change in the area of ​​longitudinal tensile reinforcement (points of theoretical break of reinforcement or change in its diameter);

in places where there is a sharp change in the cross-sectional dimensions of the element.

3.34. Elements with a constant or smoothly varying section height are not calculated based on the strength of the inclined section under the action of a bending moment in one of the following cases:

a) if all longitudinal reinforcement is brought to the support or to the end of the element and has sufficient anchorage;

b) if reinforced concrete elements are calculated in accordance with clause 1.10 of these standards;

c) in slab, spatially working structures or in structures on an elastic foundation;

d) if longitudinal stretched rods, broken along the length of the element, are inserted beyond the normal section, in which they are not required by calculation, to a length<о, определяемую по формуле

where Q is the transverse force in the normal section passing through the point of theoretical break of the rod;

F 0 . a - respectively, the cross-sectional area and the angle of inclination of bent rods located within a section of length<о;

Yr" is the force in clamps per unit length of the element in a section of length to, determined by the formula

d - diameter of the broken rod, cm.

3.35. In the corner joints of massive reinforced concrete structures (Fig. 8), the required amount of design reinforcement F 0 is determined from the condition of the strength of the inclined section passing along the bisector of the reentrant angle under the action of a bending moment*

Rice. 8. Scheme of reinforcement of corner joints of massive reinforced concrete structures

ta. In this case, the shoulder of the internal pair of forces r in the inclined section should be taken equal to the shoulder of the internal pair of forces of the smallest height A* of the root section of the mating elements.

CALCULATION OF REINFORCED CONCRETE ELEMENTS FOR ENDURANCE

3.36. Calculation of elements of reinforced concrete structures for endurance should be carried out by comparing the edge stresses in concrete and tensile reinforcement with the corresponding calculated # concrete resistances

and reinforcement R%, determined in accordance with paragraphs. 2.13 and 2.19 of these standards. Compressed reinforcement is not calculated for endurance.

3.37. In crack-resistant elements, the edge stresses in concrete and reinforcement are determined by calculation as for an elastic body but for the given sections in accordance with clause 2.22 of these standards.

In stress-resistant elements, the area and moment of resistance of the reduced section should be determined without taking into account the tensile zone of concrete. The stresses in the reinforcement should be determined in accordance with clause 4.5 of these standards.

3.38. In elements of reinforced concrete structures, when calculating the endurance of inclined sections, the main tensile stresses are absorbed by concrete if their value does not exceed R p. If the main

tensile stresses exceed R p, then their resultant must be completely transferred to the transverse reinforcement at stresses in it equal to the design resistance R,.

3.39. The magnitude of the main tensile stresses about g should be determined using the formulas:

4. CALCULATION OF ELEMENTS OF REINFORCED CONCRETE STRUCTURES ACCORDING TO LIMIT STATES OF THE SECOND GROUP

CALCULATION OF REINFORCED CONCRETE ELEMENTS FOR THE FORMATION OF CRACKS

In formulas (48) -(50): o* and m - normal and shear stress in concrete, respectively;

Ia is the moment of inertia of the reduced section relative to its center of gravity;

S n is the static moment of the part of the reduced section lying on one side of the axis, at the level of which the tangential stresses are determined;

y is the distance from the center of gravity of the reduced section to the line at the level of which the stress is determined;

b - section width at the same level.

For elements of rectangular cross-section, the tangential stress t can be determined by the formula

where 2=0.9 Lo-

In formula (48), tensile stresses should be entered with a “plus” sign, and compressive stresses with a “minus” sign.

In formula (49), the minus sign is taken for eccentrically compressed elements, and the plus sign for eccentrically stretched elements.

When taking into account normal stresses acting in the direction perpendicular to the axis of the element, the main tensile stresses are determined in accordance with clause 4.11 of chapter SNiP N-21-75 (formula 137).

4.1. Calculation of reinforced concrete elements for the formation of cracks should be carried out:

for pressure elements located in an area of ​​variable water level and subject to periodic freezing and thawing, as well as for elements that are subject to water tightness requirements taking into account the instructions of the LP. 1.7 and 1.15 of these standards;

if there are special requirements for the design standards of certain types of hydraulic structures.

4.2. Calculation of the formation of cracks normal to the longitudinal axis of the element should be carried out:

a) for centrally stretched elements according to the formula

n c ff

b) for bendable elements according to the formula

"cm<т л у/?рц V, . (53)

where shi and y are coefficients adopted according to the instructions of clause 3.5 of these standards;

Moment of resistance of the reduced section, determined by the formula

here 1 a is the moment of inertia of the reduced section;

y с is the distance from the center of gravity of the reduced section to the compressed face;

c) for eccentrically compressed elements according to the formula

where F a is the reduced cross-sectional area;

d) for eccentrically stretched elements according to the formula

4.3. Calculation of the formation of cracks under the action of a repeatedly repeated load should be made from the condition

n s ** YATs * n (57)

where op is the maximum normal tensile stress in concrete, determined by calculation in accordance with the requirements of clause 3.37 of these standards.

CALCULATION OF REINFORCED CONCRETE ELEMENTS BY CRACK OPENING

4.4. The crack opening width a t. mm normal to the longitudinal axis of the element should be determined by the formula

o t -*S d "1 7 (4-100 c) V"d. (58)

where k is the coefficient taken equal to: for bending and eccentrically compressed elements - 1; for centrally and eccentrically stretched elements - 1,2; with a multi-row arrangement of reinforcement - 1.2;

C d - coefficient taken equal when taking into account:

short-term loads - 1;

permanent and temporary long-term loads - 1.3;

repeatedly repeated load: in an air-dry state of concrete - C a -2-p a. where p* is the cycle asymmetry coefficient;

in the water-saturated state of concrete - 1.1;

1) - coefficient taken equal to: for bar reinforcement: periodic profile - 1; smooth - 1.4.

with wire reinforcement:

periodic profile - 1,2; smooth - 1.5;

<7а - напряжение в растянутой арматуре, определяемое по указаниям п. 4.5 настоящих норм, без учета сопротивления бетона растянутой зоны сечения; Онач - начальное растягивающее напряжение в арматуре от набухания бетона; для конструкций, находящихся в воде,- 0и«ч=2ОО кгс/см 1 ; для конструкций, подверженных длительному высыханию, в том числе во время строительства. - Ои«ч=0; ц-коэффициент армирования сечения,

taken equal to p=.---, but not

more than 0.02; d - diameter of reinforcement bars, mm.

for centrally stretched elements

for eccentrically stretched and eccentrically compressed elements at large eccentricities

N (e ± z) F*z

In formulas (59) and (61): r - the shoulder of the internal pair of forces, taken based on the results of the strength calculation of the section;

e is the distance from the center of gravity of the cross-sectional area of ​​the reinforcement A to the point of application of the longitudinal force JV.

In formula (61), the “plus” sign is taken for eccentric tension, and the “minus” sign for eccentric compression.

For eccentrically stretched elements at small eccentricities, o a should be determined using formula (61) with the value of e-far b replaced

By the amount -- --- for fittings

A and „a _- --- for fittings A".

The crack opening width determined by calculation in the absence of special protective measures given in clause 1.7 of these standards should be no more than the values ​​​​given in table. 15.

USSR STATE COMMITTEE FOR CONSTRUCTION

(GOSSTROY USSR)

CONSTRUCTION

NORMES AND RULES

GENERAL PROVISIONS

CONSTRUCTION

TERMINOLOGY

MOSCOW STROYIZDAT 1980

Chapter SNiP I-2 “Construction Terminology” was developed by the Central Institute of Scientific Information on Construction and Architecture (TSINIS), the Department of Technical Regulation and Standardization and the Department of Estimating Norms and Pricing in Construction of the USSR State Construction Committee with the participation of research and design institutes - the authors of the corresponding chapters of SNiP .

Considering that this chapter, included in the structure of Construction Norms and Rules (SNiP), was developed for the first time, it is issued in the form of a draft with subsequent clarification, approval by the USSR State Construction Committee and reissue in 1983.

Suggestions and comments on individual terms and their definitions that arose when applying the chapter, as well as on the inclusion of additional terms given in the chapters of SNiP, please send to VNIIIS (125047, Moscow, A-47, Gorky St., 38).

Editorial committee: engineers Sychev V.I., Govorovsky B.Ya., Shkinev A.N., Lysogorsky A.A., Bayko V.I., Shlemin F.M., Tishenko V.V., Demin I.D., Denisov N. .AND.(Gosstroy USSR), candidates of technical. sciences Eingorn M.A. And Komarov I.A.(VNIIIS).

1. GENERAL INSTRUCTIONS

1.1 . The terms and their definitions given in this chapter must be used when drawing up regulatory documents, state standards and technical documentation for construction.

The given definitions can, if necessary, be changed in the form of presentation, without violating the boundaries of concepts.

1.2 . This chapter includes the basic terms given in the corresponding chapters I - IV of the Building Codes and Rules (SNiP), for which there are no definitions or different interpretations arise.

1.3 . The terms are arranged in alphabetical order. In compound terms consisting of definitions and defined words, the main meaning-defined word is given first place, with the exception of generally accepted terms denoting the names of documents (Unified regional unit prices - EREP; Building codes and regulations - SNiP; Integrated indicators of construction costs - UPSS ; Enlarged estimate standards - USN), systems (Automated construction management system - ASUS), as well as terms with generally accepted abbreviations (master plan - general plan; construction master plan - construction plan; general contractor - general contractor).

In the Index of Terms, compound terms are presented in the most common form in normative and scientific-technical literature (without changing the word order).

The names of the terms are given primarily in the singular, but sometimes, in accordance with accepted scientific terminology, in the plural.

If a term has several meanings, then they are usually combined in one definition, but each meaning is highlighted within the last one.

2. TERMS AND THEIR DEFINITIONS

AUTOMATED CONTROL SYSTEMCONSTRUCTION(ASUS)- a set of administrative, organizational, economic and mathematical methods, computer equipment, office equipment and communications equipment, interconnected in the process of their functioning, for making appropriate decisions and verifying their implementation.

ADHESION- adhesion of dissimilar solid or liquid bodies touching their surfaces, caused by intermolecular interaction.

ANCHOR- a fastening device embedded in any fixed structure or in the ground.

ANTI-FIRE WOOD - deep or surface impregnation of wood with a solution of chemicals or mixtures (fire retardants) in order to increase its resistance to fire.

ANTISEPTIC- treatment of various non-metallic materials (wood and wood products, plastics, etc.) with chemicals (antiseptics) in order to improve their biostability and increase the service life of structures.

ENTRESOL- a platform that occupies the upper part of the volume of a residential, public or industrial building, intended to increase its area, accommodate auxiliary, storage and other premises.

FITTINGS- 1) elements, reinforcements, organically included in the material of building structures; 2) auxiliary devices and parts that are not part of the main equipment, but necessary to ensure its normal operation (pipeline fittings, electrical fittings, etc.).

REINFORCEMENT FOR REINFORCED CONCRETE STRUCTURES- an integral component (steel rod or wire) of reinforced concrete structures, which, according to its purpose, is divided into:

working (calculation), which perceives mainly tensile (and in some cases compressive) forces arising from external loads and influences, the dead weight of structures, and also intended to create pre-stress;

distribution (structural), securing the rods in the frame by welding or knitting with working reinforcement, ensuring their joint work and facilitating

uniform distribution of load between them;

mounting, which supports individual rods of working reinforcement when assembling frames and facilitates their installation in the design position;

clamps used to prevent oblique cracks in concrete structures (beams, purlins, columns, etc.) and for the manufacture of reinforcement cages from individual rods for the same structures.

INDIRECT FITTINGS- transverse (spiral, ring) reinforcement of centrally compressed elements of reinforced concrete structures, designed to increase their load-bearing capacity.

BEARING FITTINGS - reinforcement of monolithic reinforced concrete structures, capable of withstanding installation and transport loads arising during work, as well as loads from the own weight of concrete and formwork.

FITTINGSPIPELINE - devices that allow the regulation and distribution of liquids and gases transported through pipelines, and are divided into shut-off valves (taps, gate valves), safety valves (valves), regulating valves (valves, pressure regulators), outlet valves (air vents, condensate drains), emergency valves (signaling devices) and etc.

ASUS- see Automated construction management system.

WATER AERATION- saturation of water with air oxygen, carried out: in water treatment plants for the purpose of deferrization, as well as to remove free carbon dioxide and hydrogen sulfide from water; in biological wastewater treatment facilities (aeration tanks, aerofilters, biofilters) to accelerate the process of mineralization of organic substances and other contaminants dissolved in wastewater.

AERATION OF BUILDINGS - organized natural air exchange, carried out due to the difference in densities of external and internal air.

AEROTANK- a structure for the biological treatment of wastewater during its artificial aeration (i.e. when the water is saturated with air oxygen) in a mixture with activated sludge.

AEROTANK-DISPLUSTER - an aeration tank in which wastewater and activated sludge are injected concentratedly from one end side of the corridor, and are also discharged concentratedly from the opposite end side of the corridor.

AEROTANK-SETTENTION TANK - a structure in which an aeration tank and a settling tank are structurally and functionally combined and are in direct technological connection with each other.

AEROTANK-MIXER - an aeration tank in which wastewater and activated sludge are supplied evenly along one long side of the corridor, and discharge along the other side of the corridor.

AIR FILTER- biofilter with devices for forced ventilation.

PRODUCTION BASE CONSTRUCTIONORGANIZATIONS- a complex of enterprises and structures of a construction organization intended for the prompt provision of objects under construction with the necessary material and technical resources, as well as for the manufacture (processing, enrichment) of materials, products and structures used in the construction process on their own.

BYPASS- a bypass pipeline with shut-off valves for removing the transported medium (liquid, gas) from the main pipeline and supplying it to the same pipeline.

EXPANSION TANK - a reservoir in a closed water heating system to receive the excess volume of water generated when it is heated to its maximum operating temperature.

BANQUET- 1) an earthen rampart placed on the upland side of the road excavation to protect it from surface water runoff; 2) a prism filled with stone in the upper and lower parts of the dam, constructed from soil materials.

SPLAY POOL - an open tank with a system of pressure pipelines to lower the temperature of circulating water by spraying it in the air, used in circulating water supply systems of industrial enterprises that use thermal power plants, compressors, etc.

TOWER- a free-standing high-rise structure, the stability of which is ensured by its main structure (without guy wires).

BERM- a ledge arranged on the slopes of earthen (stone) embankments, dams, canals, fortified banks, quarries, etc. or between the base of an embankment (road or railway) and a reserve (drainage ditch) to impart stability to the overlying part of the structure and protect it from erosion by atmospheric water, as well as to improve the operating conditions of the structure.

BIOSTABILITY- the property of materials and products to resist rotting or other destructive biological processes.

IMPROVEMENT- a set of works (on engineering preparation of the territory, construction of roads, development of communication networks and structures for water supply, sewerage, energy supply, etc.) and measures (on clearing, draining and landscaping of the territory, improving the microclimate, protecting against pollution of the air basin, open water bodies and soil , sanitary cleaning, noise reduction, etc.), carried out in order to bring a particular territory into a state suitable for construction and normal use for its intended purpose, creating healthy, comfortable and cultural living conditions for the population.

VOLUMETRIC BLOCK- a prefabricated part of the volume of a building under construction for residential, public or industrial purposes (sanitary cabin, room, apartment, utility room, transformer substation, etc.).

BLOCK SECTION- a volumetric-spatial element of a building, independent in functional terms, which can be used both in combination with other elements of the building and independently.

BLOCK CONSTRUCTION AND TECHNOLOGY- interconnected elements of assembled building structures and equipment, previously combined at an enterprise or construction site into a single unchangeable volumetric-spatial system.

RACE- an open or closed hydraulic structure for connecting free-flow sections of a water pipeline (reservoir), located at different levels, in which the passage of water from the upper section to the lower is carried out at higher (more critical) speeds without separating the flow from the contour of the structure itself.

PIPELINE ENTRY- a pipeline branch from the external network to a unit with shut-off valves located inside the building (structure).

VENTILATION - natural or artificial controlled air exchange in rooms (confined spaces), ensuring the creation of an air environment in accordance with sanitary, hygienic and technological requirements.

VERANDA- an open or glazed unheated room attached to or built into a building, as well as constructed separately from the building in the form of a light pavilion.

LOBBY- a room in front of the entrance to the internal parts of the building, designed to receive and distribute the flow of visitors.

MOISTURE RESISTANCE- the ability of building materials to long-term resist the destructive effects of moisture during periodic wetting and drying of the material.

APRON- an element for fastening the bottom of a watercourse directly behind the spillway (spillway) of the dam in the form of a massive slab designed to absorb the impacts of jets and dampen the energy of the overflowing flow of water, as well as to protect the bed of the watercourse and the soil of the base of the structure from erosion.

WATER POWER- a structure in the form of a tunnel, channel, tray or pipeline for passing (supplying) water under pressure or gravity from a water intake (water intake structure) to the place of its consumption.

WATER INTERCEPTION (WATER INTERCEPTION STRUCTURE)- a hydraulic structure for collecting water from an open watercourse or reservoir (river, lake, reservoir) or underground sources and supplying it to water pipelines for subsequent transportation and use for economic purposes (irrigation, water supply, electricity generation, etc.).

DRAINAGE- a set of measures and devices that ensure the removal of ground and (or) surface water from open excavations (pits), quarries or groundwater from adits, mines and other mine workings.

WATER TREATMENT- a set of technological processes by which the quality of water entering the water supply system from a water supply source is brought to the established standard indicators.

WATER TREATMENT- water treatment (deferrization, desalting, desalination, etc.), making it suitable for powering steam and hot water boilers or for various technological processes.

WATER REDUCTION - a method of lowering the water level in the ground or a reservoir adjacent to a body of soil during the construction period using drainage devices installed in aquifers, deep pumps, wellpoints, etc.

WATER INTERMINER- 1) part of a water intake structure used to directly receive water from an open (river, lake, reservoir) or underground source; 2) a watercourse, reservoir or hollow that receives and discharges water collected by a reclamation drainage system from the adjacent territory.

WATER PIPES- a complex of engineering structures and devices for obtaining water from natural sources, purifying it, transporting it to various consumers in the required quantity and required quality.

SPILLWAY (SPILLOW STRUCTURE)- a hydraulic structure for passing water discharged from the upstream to the downstream in order to avoid exceeding the maximum design water levels in the reservoir, through surface openings (spillways) on the dam crest or through deep holes (spillways) located below the water level in the upstream, or through both at the same time.

Spillway- 1) surface spillway with free (non-pressure) overflow of water over the crest of the barrier; 2) an obstacle, a threshold through which a stream of water flows.

WATER SUPPLY- a set of measures to provide water to various consumers (population, industrial enterprises, transport, agriculture) in the required quantities and required quality.

WATERWAY (WATERWAY STRUCTURE)- deep spillway in the form of holes (pipes) in a hydraulic structure or a separate structure for emptying the reservoir, washing bottom sediments deposited in the upper pool, and for passing (discharging) water into the lower pool.

AQUITTER- see Waterproof soil layer.

IMPACT- a phenomenon that causes internal forces in structural elements (from uneven deformations of the base, from deformations of the earth’s surface in areas influenced by mine workings and in karst areas, from temperature changes, from shrinkage and creep of structural materials, from seismic, explosive, humidity and other similar phenomena ).

DUCT- a pipeline (duct) for moving air, used in ventilation systems, air heating, air conditioning, as well as for transporting air for technological purposes.

AIR EXCHANGE- partial or complete replacement of polluted indoor air with clean air.

AIR TREATMENT - air treatment (removal of dust, harmful gases, impurities, heating, cooling, humidification, dehumidification, etc.) to give it qualities that meet technological or sanitary-hygienic requirements.

MINING WORKING - a cavity in the earth's crust formed as a result of mining operations for the purpose of exploration and extraction of minerals, geotechnical surveys and construction of underground structures.

TRAMPING THE PIT - the process of forming a pit in large-porous subsidence or bulk soil by compaction using mechanical impact compactors with a working body in the form of a stamp.

VISCOSITY IMPACT- a conditional mechanical characteristic of a material that evaluates its resistance to brittle fracture.

SIZE- maximum external outlines or dimensions of structures, buildings, structures, devices, vehicles, etc.

LOADING DIMENSION- the maximum transverse (perpendicular to the axis of the railway track) outline in which the cargo must be placed (taking into account packaging and fastening) on ​​an open rolling stock when it is on a straight horizontal track.

SIZE OF ROLLING STOCK - the maximum transverse (perpendicular to the axis of the track) outline in which rolling stock installed on a straight horizontal track should be placed, both in an empty and loaded state, having maximum normalized tolerances and wear, with the exception of lateral inclination on springs.

UNDER BRIDGE NAVIGABLE- transverse (perpendicular to the direction of flow of the watercourse) outline of the space under the bridge, formed by the bottom of the span, the design navigable horizon and the edges of the supports, into which structural elements of the bridge or devices located under it should not go.

SIZE OF APPROACHING BUILDINGS- limit transverse (perpendicular to the axis of the track) outline, into which, in addition to the rolling stock, no parts of structures and devices, as well as materials, spare parts and equipment, should not go inside, with the exception of parts of devices intended for direct interaction with the rolling stock, provided that the position of these devices in the internal space is linked to the parts of the rolling stock with which they can come into contact, and that they cannot cause contact with other elements of the rolling stock.

GAS CLEANING- technological process of separating solid, liquid or gaseous impurities from industrial gases.

GAS PIPELINE- a set of pipelines, equipment and devices intended for transporting flammable gases from any point to consumers.

MAIN GAS PIPELINE - a gas pipeline for transporting flammable gases from the place of their extraction (or production) to gas distribution stations, where the pressure is reduced to the level necessary to supply consumers.

GAS SUPPLY- organized supply and distribution of gas fuel for the needs of the national economy and population.

GALLERY- 1) above-ground or above-ground, fully or partially closed, horizontal or inclined extended structure connecting the premises of buildings or structures, intended for engineering and technological communications, as well as for the passage of people; 2) the upper tier of the auditorium.

ANTI-CLAVE GALLERY - a structure that protects a section of a railway or highway from mountain landslides.

DEVELOPMENT DAMPENER - a device in a water basin that serves to change the direction of jets and spread (across the width) of the water flow in order to extinguish excess kinetic energy of water and redistribute flow speeds in the downstream of the spillway dam.

GENERAL PLAN (GEN PLAN) - part of the project containing a comprehensive solution to the issues of planning and improvement of the construction site, placement of buildings, structures, transport communications, utility networks, organization of economic and public service systems.

GENERAL CONTRACTOR (GENERAL CONTRACTOR)- a construction organization that, on the basis of a concluded contract agreement with the customer, is responsible for the timely and high-quality implementation of all construction work stipulated by the contract on this facility, involving, if necessary, other organizations as subcontractors.

GENERAL PLAN- see General plan.

GENERAL CONTRACTOR- see General contractor.

SEALANTS- elastic or plastoelastic materials used to ensure the tightness of joints and connections of structural elements of buildings and structures.

COOLING TOWER- a structure for cooling water that removes heat from fuel-generating equipment with atmospheric air in recycling water supply systems of industrial enterprises and in air conditioning devices due to the evaporation of part of the water flowing down the sprinkler.

PRIMING- a generalized name for all types of rocks that are the object of human engineering and construction activities.

PRESSURE- a quantity characterizing the intensity of forces acting on any part of the surface of a body in directions perpendicular to this surface, and determined by the ratio of the force uniformly distributed over the surface normal to it to the area of ​​this surface .

MOUNTAIN PRESSURE- forces acting on the lining (support) of an underground mine from the surrounding rock, the equilibrium state of which is disturbed due to natural (gravity, tectonic phenomena) and production (underground work) processes.

DAM- a hydraulic structure in the form of an embankment for protecting river and sea coastal lowlands from flooding, for embanking canals, connecting pressure hydraulic structures with the banks (pressure dams), for regulating river channels, improving navigation conditions and the operation of culverts and water intake structures (gravity dams).

DERIVATION- a system of structures for draining water from a river, reservoir or other body of water and transporting it to the station node of a hydroelectric power station (inlet D.), as well as for draining water from it (outlet D.).

CONSTRUCTION DETAIL- part of a building structure made of homogeneous material without the use of assembly operations.

DEFORMATIVITY - the property of materials being flexible to change in original shape.

DEFORMATION- change in the shape or size of the body (body part) under the influence of any physical factors (external forces, heating and cooling, changes in humidity and other influences).

DEFORMATION OF A BUILDING (STRUCTURE)- change in shape and size, as well as loss of stability (settlement, shear, roll, etc.) of a building or structure under the influence of various loads and influences.

STRUCTURE DEFORMATION - change in the shape and size of a structure (or part of it) under the influence of loads and influences.

BASE DEFORMATION - deformation resulting from the transfer of forces from a building (structure) to the foundation or changes in the physical state of the foundation soil during the construction and operation of the building (structure).

RESIDUAL DEFORMATION - part of the deformation that does not disappear after the removal of the loads and influences that caused it.

PLASTIC DEFORMATION - residual deformation without microscopic disturbances in the continuity of the material, resulting from the influence of force factors.

ELASTIC DEFORMATION - deformation that disappears after the load that caused it is removed.

DIAPHRAGM DESIGN- a solid or lattice element of a spatial structure that increases its rigidity.

DAM DIAPHRAGM - an anti-filtration device inside the body of a dam constructed from soil materials, made in the form of a wall made of non-soil materials (concrete, reinforced concrete, metal, wood or polymer film materials).

DISPATCHING - a system of centralized operational management of all levels of construction production to ensure the rhythmic and integrated production of construction and installation works by regulating and monitoring the implementation of operational plans and production schedules and to provide it with material and technical resources, coordinating the work of all subcontractors, auxiliary production and service facilities.

DEPARTMENTAL REGULATORY DOCUMENT- a regulatory document establishing requirements on issues specific to the industry and not regulated by all-Union regulatory documents, approved in the prescribed manner by the ministry or department.

NATIONAL UNION REGULATIVE DOCUMENT- a regulatory document containing mandatory requirements for design and construction.

REPUBLICAN NORMATIVE DOCUMENT- a normative document establishing requirements on issues specific to the Union republic and not regulated by all-Union normative documents.

PRODUCTION DOCUMENTATION- a set of documents reflecting the progress of construction and installation work and the technical condition of the construction project (as-built diagrams and drawings, work schedules, acceptance certificates and statements of completed volumes of work, general and special work logs, etc.).

DURABILITY - the ability of a building or structure and its elements to maintain specified qualities over time under certain conditions under an established operating mode without destruction or deformation.

ADMISSION- the difference between the largest and smallest limit sizes, equal to the arithmetic sum of the permissible deviations from the nominal size.

DRAIN- underground artificial device (pipe, well, cavity) for collecting and draining groundwater.

DRAINAGE- a system of pipes (drains), wells and other devices for collecting and draining groundwater in order to lower its level, drain the soil mass near the building (structure), and reduce filtration pressure.

DUKER- a pressure section of a pipeline laid under a river bed (canal), along the slopes or bottom of a deep valley (ravine), under a road located in a excavation.

UNIFORM DISTRICT UNIT RATES (EREP)- unit prices for general construction and special work, centrally developed on the basis of estimate standards of Part IV of the Construction Norms and Rules (SNiP) and approved for regions of the country according to the accepted territorial division.

ENDOVA- the space between two adjacent roof slopes, forming a tray (incoming corner) for collecting water on the roof.

EREP- see Unified regional unit prices.

RIGIDITY- characteristic of a structure that evaluates the ability to resist deformation.

Slaughter- a workplace where soil development takes place in an open or underground manner, moving during the work process.

AIR-THERMAL CURTAIN - a device that prevents the entry of outside cold air into a room through open openings (doors, gates) by pumping heated air with a fan towards the flow trying to penetrate into the room.

ANTI-FILTRATION CURTAIN- an artificial barrier to the filtration flow of water, created in the soil of the base of a retaining hydraulic structure and in its coastal abutments (by injection of solutions, mixtures) to lengthen filtration paths, reduce filtration pressure on the base of the structure, and reduce water loss due to filtration.

BACKGROUND- the volume of unfinished construction in terms of capacity, the volume of capital investments and the volume of construction and installation work, which must be actually completed at start-up facilities and complexes moving into the periods following the planned ones, in order to ensure the systematic commissioning of fixed assets and the rhythm of construction production.

POWER BACKGROUND - the total design capacity of enterprises that should be under construction at the end of the planning period, minus the capacities introduced from the beginning of their construction to the end of the planning period.

BACKGROUND FOR CAPITAL INVESTMENTS- the cost of construction and installation work and other costs included in the estimated cost of objects, which must be absorbed by the end of the planning period at transitional construction sites.

BACKGROUND FOR CONSTRUCTION AND INSTALLATION WORK- part of the backlog for the volume of capital investments, including the cost of construction and installation work that must be completed on transitional construction sites by the end of the planning period.

CUSTOMER(developer) - an organization, enterprise or institution to which funds are allocated in national economic plans for capital construction or which have their own funds for these purposes and, within the limits of the rights granted to them, enter into an agreement for design, survey, construction and installation work with a contractor ( contractor).

PLEDGE- a series of hammer blows on a pile driven into the ground, performed to measure the average value of its failure.

SOAKSOIL- a method of compacting subsidence soils by flooding with water until a given stabilization of subsidence.

FREEZING SOILS- a method of temporarily strengthening weak water-saturated soils with the formation of an ice-soil massif of given dimensions and strength by circulating coolant through pipes immersed in the frozen soil.

WATER SEAL- see Hydraulic shutter.

HYDRAULIC VALVE (WATER VALVE)- a device that prevents the penetration of gases from one space to another (from a pipeline to a room, from one section of a pipeline to another), in which the flow of gases in an undesirable direction is prevented by a layer of water.

HYDRAULIC VALVE - a movable waterproof device for closing and opening the culverts of a hydraulic structure (spillway dam, sluice, pipeline, hydraulic tunnel, fish passage, etc.) in order to control the flow of water passing through them.

DIRECT COSTS- the main component of the estimated cost of construction and installation work, including the cost of all materials, products and structures, energy resources, wages of workers and the cost of operating construction machines and mechanisms.

TIGHTENING- a rod element that absorbs tensile forces in the spacer structure of arches, vaults, rafters, etc. and connecting the end nodes of building structures.

CAPTURE- a section of a building or structure intended for continuous execution of construction and installation work with the composition and scope of work repeated in this and subsequent sections.

CLEANING THE PITCH- removal of a layer of soil from the surface of the bottom and walls of the pit, developed with a shortage.

BUILDING- a building system consisting of load-bearing and enclosing or combined (load-bearing and enclosing) structures forming a closed ground volume intended for residence or stay of people, depending on the functional purpose and for performing various types of production processes.

RESIDENTIAL BUILDINGS- apartment buildings for permanent residence of people and hostels for living during work or study.

BUILDINGS AND STRUCTURES TEMPORARY- specially erected or temporarily adapted (permanent) buildings (residential, cultural, social and other) and structures (industrial and auxiliary purposes) for the period of construction, necessary to serve construction workers, organize and perform construction and installation work.

PUBLIC BUILDINGS AND STRUCTURES- buildings and structures intended for social services to the population and for housing administrative institutions and public organizations.

INDUSTRIAL BUILDINGS- buildings for housing industrial and agricultural production and providing the necessary conditions for people to work and operate technological equipment.

ROAD-CLIMATE ZONE - a conventional part of the country's territory with climatic conditions that are homogeneous in terms of the construction of highways, characterized by a combination of water and thermal conditions, depth, groundwater, depth of soil freezing and the amount of precipitation characteristic only of this area.

SECURITY ZONE- a zone in which a special security regime for placed objects is established.

WORKING AREA- the area where construction and installation work is directly carried out and the necessary materials, finished structures and products, machines and devices are placed.

SANITARY PROTECTION ZONE- a zone separating an industrial enterprise from the residential territory of cities and other populated areas, within which the placement of buildings and structures, as well as landscaping of the territory, are regulated by sanitary standards.

SANITARY PROTECTION ZONE- territory and water area, within certain boundaries of which a special sanitary regime is established, excluding the possibility of infection and contamination of water supplies.

DAM TOOTH- a dam element in the form of a protrusion connected to the foundation and recessed into the base, which serves to lengthen the path of water filtration and increase the stability of the dam.

CONSTRUCTION PRODUCT- a factory-made element supplied for construction in finished form.

ENGINEERING SURVEYS- a set of technical and economic studies of the construction area, allowing to justify its feasibility and location, to collect the necessary data for the design of new or reconstruction of existing facilities.

INDUSTRIALIZATION - organization of construction production using complex mechanized processes for the construction of buildings and structures and progressive construction methods and the widespread use of prefabricated structures, including enlarged ones with high factory readiness.

INSTRUCTIONS- a normative all-Union (SN), republican (RSN) or departmental (VSN) document in the system of building codes and regulations, establishing the norms and rules: design of enterprises in certain industries, as well as buildings and structures for various purposes, structures and engineering equipment; production of certain types of construction and installation works; application of materials, structures and products; on the organization of design and survey work, mechanization of work, labor standardization and development of design and estimate documentation