Bolted connections design and calculation. Measures to prevent loosening of bolts

CJSC "TsNIIPSK im. Melnikov
OAO NIPI Promstalkonstruktsiya
ORGANIZATION STANDARD

Steel building structures

BOLT CONNECTIONS

Design and calculation

STO 0041-2004

(02494680, 01408401)

Moscow 2004

Ccontent

Foreword

1 DEVELOPED CJSC Central Order of the Red Banner of Labor Research and Design Institute of Building Metal Structures. Melnikova (CJSC "TsNIIPSK named after Melnikov")

OJSC Research and Design Institute "Promstalkonstruktsiya"

2 INTRODUCED by the organizations developing the Standard

3 ADOPTED at the Scientific and Technical Council TsNIIPSK them. Melnikov dated November 25, 2004 with the participation of representatives of the organization that developed the Standard

4 INTRODUCED for the first time

5 REVISION November 2005

6 Development, approval, approval, publication (replication), updating (change or revision) and cancellation of this standard are carried out by developing organizations

Introduction

This standard was developed in accordance with the Federal Law "On Technical Regulation" No. 184-FZ and is intended for use by all departments of ZAO TsNIIPSK im. Melnikov" and JSC NIPI "Promstalkonstruktsiya", specializing in the development of projects of KM and KMD, diagnostics, repair and reconstruction of industrial buildings and structures for various purposes.

The standard can be applied by other organizations if these organizations have certificates of conformity issued by the Certification Bodies in the voluntary certification system created by the standard development organizations.

Organizations-developers do not bear any responsibility for the use of this standard by organizations that do not have certificates of conformity.

The need to develop a standard is dictated by the fact that the experience gained by the organizations developing the standard, as well as domestic enterprises and organizations in the field of design, manufacture and implementation of steel structures with bolted field connections, is contained in various regulatory documents, recommendations, departmental rules and others, in part obsolete and not generally covering the problem of safe operation of industrial buildings and structures for various purposes.

The main purpose of developing the standard is to create a modern regulatory framework for the design and calculation of steel structures with bolted connections.

ORGANIZATION STANDARD

Approved and put into effect:

Introduction date 2005-01-01

1 area of use

1.1 This standard applies to the design and calculation of steel structures with bolted field connections, including high-strength ones, designed for load-bearing and enclosing structures of buildings and structures for various purposes, perceiving permanent, temporary and special loads in climatic regions with a design temperature of up to -65 ° With and seismicity up to 9 points, operated both in slightly aggressive and in medium aggressive and aggressive environments with the use of protective metal coatings.

1.2 The standard sets out the main provisions for the design and calculation of bolted connections, working in shear and tension, shows the areas of rational use of bolts of various diameters and strength classes.

2 Normative references

This standard uses references to the following normative documents:

Federal Law "On Technical Regulation" dated December 27, 2002 No. 184-FZ

for crushing, taking into account friction

Nbp- design force on crushing, determined by the formula

Qbh- design force perceived by friction forces, determined by the formula;

Tou- coefficient that takes into account the reduction in the preload of the bolts after a total shear in the joint, taken equal to:

0.9 - differences in the nominal diameters of holes and bolts δ ≤ 0.3 mm;

0.85 - at δ = 1.0 mm;

0.80 - at δ = 2.0 mm;

0.75 - at δ = 3.0 mm;

nf- the number of friction surfaces of the connected elements.

7.5 Quantity nbolts in the joint under the action of a longitudinal force N should be determined by the formula

Nmin- the smaller of the design forcesNbs and NbhFor one bolt, calculated by the formulas and .

7.6 The strength of elements weakened for bolts should be checked taking into account the complete weakening of the sections by bolt holes.

7.7 In single shear connections, the number of bolts should be increased by 10% against the calculation.

7.8 Endurance calculation of friction shear joints should be performed in accordance with the requirements of clause 9.2 of SNiP II-23-81 *, classifying joints with steel elements with a tensile strength of more than 420 MPa to the 2nd group of structures, less than 420 MPa - to the 3rd group.

8 Flange connections

8.1 The recommendations of this section should be observed when designing, manufacturing and mounting assembly of flanged joints of open profile elements (I-beams, T-beams, channels, etc.) of steel structures of industrial buildings subject to tension, tension with bending with an unambiguous diagram of tensile stresses σ min/σ check≥ 0.5), as well as the action of local transverse forces.

The recommendations do not apply to flange connections: perceiving alternating loads, as well as repeatedly acting movable, vibrational or other types of loads with a number of cycles over 10 5 with a stress asymmetry factor in the connected elements R= σ min/σ check ≤ 0,8;

operated in a highly aggressive environment.

8.2 Flange connections should only be made with prestressed high strength bolts. Bolt preload value At 0 for calculations should be taken equal to

B 0 \u003d 0.9Bp=0.9RbhA bn,(11)

where In r- design tensile force of the bolt;

Rbh = 0.7 Rbun- design tensile strength of bolts;

Rbun- normative resistance of steel bolts;

A bn - net cross-sectional area of the bolt.

8.3 For flange connections, high-strength bolts M20, M24 and M27 made of steel 40X "select" of KhL execution with standard tensile strength should be usedR bunnot more than 1080 MPa (110 kgf / mm 2), as well as high-strength nuts and washers for them according toGOST 22353-77- GOST 22356-77.

8.4 For flanges, sheet steel should be used in accordance with GOST 19903-74 * grade 09G2S-15 in accordance with GOST 19281-89 and 14G2AF-15 in accordance with TU 14-105-465-82 with guaranteed mechanical properties in the direction of the rolled thickness.

8.5 Flanges can be made of other grades of low-alloy steels according to GOST 19281-89, intended for building steel structures, while:

steel must be at least category 12;

temporary resistance and relative narrowing of steel in the direction of the thickness of the rolled products must beσ bz≥ 0,8 σ b, ψ z ≥ 20% (where σ b- normative value of temporary resistance for the base metal, taken according to standards or specifications).

a- from wide-shelf brands; b- from paired equal corners

8.10 When calculating the strength of bolts and a flange related to the outer zone, sections of the flange are distinguished, which are considered as T-shaped flange connections with a widthw(cm. ).

,(14)

where Nj- design forcej-th bolt of the outer zone, equal to

;(15)

here Nbj- design force onj-th bolt, determined from the condition of the strength of the connection by bolts

,(16)

a, β - coefficients taken according to the table. eight;

x j- bolt stiffness parameter, determined by the formula

;(17)

b j- axle distancej-th bolt to the edge of the weld;

Steel structures at the construction site are almost always connected using bolted connection and it has many advantages over other connection methods and, above all, welded connection - this is the ease of installation and quality control of the connection.

Among the shortcomings, one can note a large metal consumption compared to a welded joint, because. in most cases, overlays are needed. In addition, the bolt hole weakens the section.

There are a great many types of bolted connections, but in this article we will consider the classic connection used in building structures.

SNiP II-23-81 Steel structures

SP 16.13330.2011 Steel structures (Updated version of SNiP II-23-81)

SNiP 3.03.01-87 Bearing and enclosing structures

SP 70.13330.2011 Bearing and enclosing structures (Updated version of SNiP 3.03.01-87)

STO 0031-2004 Bolted connections. Product range and applications

STO 0041-2004 Bolted connections. Design and calculation

STO 0051-2006 Bolted connections. Manufacturing and installation

Types of bolted connections

According to the number of bolts: single-bolt and multi-bolt. I don't think it needs to be explained.

By the nature of the transfer of force from one element to another:

Not shear-resistant and shear-resistant (friction). To understand the meaning of this classification, let's consider how a bolted connection works in the general case when working in shear.

As you can see, the bolt compresses the 2nd plates and part of the effort is perceived by friction forces. If the bolts do not compress the plates strongly enough, then the plates slip and the force Q is perceived by the bolt.

The calculation of non-shear connections implies that the tightening force of the bolts is not controlled and the entire load is transmitted only through the bolt without taking into account the resulting friction forces. Such a connection is called a connection without controlled tension of the bolts.

Shear or friction joints use high-strength bolts that tighten the plates with such a force that the load Q is transferred through frictional forces between the 2 plates. Such a connection can be friction or friction-shear, in the first case, only friction forces are taken into account in the calculation, in the second, friction forces and the shear strength of the bolt are taken into account. Although the friction-shear connection is more economical, it is very difficult to implement it in practice in a multi-bolt connection - there is no certainty that all the bolts can simultaneously bear the load on the shear, therefore it is better to calculate the friction connection without taking into account the shear.

At high shear loads, a friction connection is more preferable. the metal content of this compound is less.

Types of bolts by accuracy class and their application

Accuracy class A bolts - these bolts are installed in holes drilled to the design diameter (i.e. the bolt fits into the hole without clearance). Initially, the holes are made of a smaller diameter and gradually reamed to the desired diameter. The diameter of the hole in such connections should not exceed the diameter of the bolt by more than 0.3 mm. It is extremely difficult to make such a connection, so they are practically not used in building structures.

Bolts of accuracy class B (normal accuracy) and C (coarse accuracy) are installed in holes 2-3 mm larger than the diameters of the bolts. The difference between these bolts is the bolt diameter error. For bolts of accuracy class B, the actual diameter may deviate by no more than 0.52 mm, for bolts of accuracy class C up to 1 mm (for bolts with a diameter of up to 30 mm).

For building structures, as a rule, bolts of accuracy class B are used. in the realities of installation on a construction site, it is almost impossible to achieve high accuracy.

Types of bolts by strength and their application

For carbon steels, the strength class is indicated by two numbers through a dot.

There are the following bolt strength classes: 3.6; 3.8; 4.6; 4.8; 5.6; 5.8; 6.6; 8.8; 9.8; 10.9; 12.9.

The first digit in the classification of bolt tensile strength indicates the tensile strength of the bolt - one unit indicates a tensile strength of 100 MPa, i.e. the ultimate strength of a bolt of strength class 9.8 is 9x100=900 MPa (90 kg/mm²).

The second digit in the classification of the strength class indicates the ratio of the yield strength to the tensile strength in tens of percent - for a bolt of strength class 9.8, the yield strength is 80% of the tensile strength, i.e. the yield strength is 900 x 0.8 = 720 MPa.

What do these numbers mean? Let's look at the following diagram:

Here is a general case of steel tensile testing. The horizontal axis indicates the change in the length of the test specimen, and the vertical axis indicates the applied force. As you can see from the diagram, with an increase in force, the length of the bolt changes linearly only in the area from 0 to point A, the stress at this point is the yield point, then with a slight increase in load, the bolt stretches more, at point D the bolt breaks - this is the tensile strength . In building structures, it is necessary to ensure the operation of a bolted connection within the yield strength.

The strength class of the bolt must be indicated on the end or side surface of the bolt head.

If there is no marking on the bolts, then most likely these are bolts of a strength class below 4.6 (their marking is not required according to GOST). The use of bolts and nuts without marking is prohibited in accordance with SNiP 3.03.01.

On high-strength bolts, the melting symbol is additionally indicated.

For the bolts used, it is required to use nuts corresponding to their strength class: for bolts 4.6, 4.8 nuts of strength class 4 are used, for bolts 5.6, 5.8 nuts of strength class 5, etc. It is possible to replace nuts of one strength class with higher ones (for example, if it is more convenient to complete nuts of one strength class for an object).

When bolts are used only for shear, it is allowed to use the strength class of nuts with the strength class of bolts: 4 - at 5.6 and 5.8; 5 - at 8.8; 8 - at 10.9; 10 - at 12.9.

Stainless steel bolts are also marked on the bolt head. Steel class - A2 or A4 and tensile strength in kg / mm² - 50, 70, 80. For example A4-80: steel grade A4, strength 80 kg / mm² \u003d 800 MPa.

The strength class of bolts in building structures should be determined in accordance with Table D.3 of SP 16.13330.2011

Choice of bolt steel grade

The bolt steel grade should be assigned according to Table D.4 of SP 16.13330.2011

Selection of bolt diameter for constructionstructures

For connections of building metal structures, bolts with a hexagonal head of normal accuracy according to GOST 7798 or increased accuracy according to GOST 7805 with a coarse thread pitch of diameters from 12 to 48 mm of strength classes 5.6, 5.8, 8.8 and 10.9 according to GOST 1759.4, hex nuts of normal accuracy according to GOST 5915 or increased accuracy according to GOST 5927 strength classes 5, 8 and 10 according to GOST 1759.5, round washers for them according to GOST 11371 execution of 1 accuracy class A, as well as high-strength bolts, nuts and washers according to GOST 22353 - GOST 22356 diameters 16, 20 , 22, 24, 27, 30, 36, 42 and 48 mm.

The diameter and number of bolts are selected so as to provide the necessary strength of the assembly.

If significant loads are not transmitted through the connection, then M12 bolts can be used. To connect loaded elements, it is recommended to use bolts from M16, for foundations from M20.

for M12 bolts - 40 mm;

for M16 bolts - 50 mm;

for M20 bolts - 60 mm;

for M24 bolts - 100 mm;

for M27 bolts - 140 mm.

Bolt hole diameter

For bolts of accuracy class A, the holes are made without clearance, but the use of such a connection is not recommended due to the great complexity of its manufacture. In building structures, as a rule, bolts of accuracy class B are used.

For bolts of accuracy class B, the hole diameter can be determined from the following table:

Bolt spacing

Distances when placing bolts should be taken in accordance with Table 40 of SP 16.13330.2011

In joints and nodes, bolts must be located closer to each other, and structural connecting bolts (used to connect parts without transferring significant loads) at maximum distances.

It is allowed to fasten parts with one bolt.

Choice of bolt length

We determine the length of the bolt as follows: add up the thicknesses of the elements to be joined, the thicknesses of the washers and nuts, and add 0.3d (30% of the bolt diameter) and then look at the assortment and select the nearest length (rounded up). According to building codes, the bolt must protrude from the nut by at least one turn. A bolt that is too long cannot be used. there is a thread only at the end of the bolt.

For convenience, you can use the following table (from the Soviet reference book)

In shear bolted connections, with an outer element thickness of up to 8 mm, the thread must be outside the package of connected elements; in other cases, the bolt thread should not go deeper into the hole by more than half the thickness of the extreme element on the side of the nut or more than 5 mm. If the selected bolt length does not meet this requirement, then the bolt length must be increased to meet this requirement.

Here's an example:

The bolt works in shear, the thickness of the fastened elements is 2x12 mm, according to the calculation, a bolt with a diameter of 20 mm, a washer thickness of 3 mm, a spring washer thickness of 5 mm, and a nut thickness of 16 mm are accepted.

The minimum length of the bolt is: 2x12 + 3 + 5 + 16 + 0.3x20 = 54 mm, according to GOST 7798-70, we select the M20x55 bolt. The length of the threaded part of the bolt is 46 mm, i.e. the condition is not satisfied because the thread should go deep into the hole by no more than 5 mm, so we increase the length of the bolt to 2x12 + 46-5 = 65 mm. According to the norms, an M20x65 bolt can be accepted, but it is better to use an M20x70 bolt, then all the threads will be outside the hole. The spring washer can be replaced with a regular one and another nut can be added (very often this is done because the use of spring washers is limited).

Measures to prevent loosening of bolts

To ensure that the fastening does not loosen over time, it is required to use a 2nd nut or lock washers to prevent unscrewing of the bolts and nuts. If the bolt is in tension, then a 2nd bolt must be used.

There are also special nuts with a retaining ring or flange.

Do not use spring washers for oval holes.

Washer installation

No more than one washer should be installed under the nut. It is also allowed to install one washer under the bolt head.

Strength calculation of a bolted connection

Bolted connection can be divided into the following categories:

1) connection working in tension;

2) shear connection;

3) connection working on shear and tension;

4) friction connection (working in shear, but with a strong bolt tension)

Calculation of a bolted connection in tension

In the first case, the strength of the bolt is checked according to the formula 188 SP 16.13330.2011

where Nbt is the tensile strength of one bolt;

Rbt is the design tensile strength of the bolt;

Calculation of a bolted shear connection

If the connection works on a slice, then you need to check 2 conditions:

shear calculation according to formula 186 SP 16.13330.2011

where Nbs is the bearing capacity of one bolt per shear;

Rbs is the design shear strength of the bolt;

Ab is the gross sectional area of the bolt (accepted in accordance with Table D.9 of SP 16.13330.2011);

ns is the number of cuts of one bolt (if the bolt connects 2 plates, then the number of cuts is one, if 3, then 2, etc.);

γb is the operating condition coefficient of the bolted connection, taken in accordance with Table 41 of SP 16.13330.2011 (but not more than 1.0);

γc is the coefficient of working conditions, taken according to Table 1 of SP 16.13330.2011.

and calculation for collapse according to the formula 187 SP 16.13330.2011

where Nbp is the bearing capacity of one bolt in collapse;

Rbp is the design bearing strength of the bolt;

db is the outside diameter of the bolt shank;

∑t - the smallest total thickness of the connected elements, crushed in one direction (if the bolt connects the 2nd plates, then the thickness of one of the thinnest plates is taken, if the bolt connects 3 plates, then the sum of the thicknesses for the plates that transmit the load in one direction and compared with the thickness of the plate that transfers the load in the other direction and takes the smallest value);

γb is the coefficient of the working condition of the bolted connection, taken in accordance with Table 41 of SP 16.13330.2011 (but not more than 1.0)

γc is the coefficient of working conditions, taken according to Table 1 of SP 16.13330.2011.

Design resistance of bolts can be determined according to Table D.5 of SP 16.13330.2011

The design resistance Rbp can be determined from Table D.6 of SP 16.13330.2011

The calculated cross-sectional areas of the bolts can be determined from Table D.9 of SP 16.13330.2011

Calculation of a connection working in shear and tension

With the simultaneous action on the bolted connection of forces that cause shear and tension of the bolts, the most stressed bolt, along with the check according to the formula (188), should be checked according to the formula 190 SP 16.13330.2011

where Ns, Nt are the forces acting on the bolt, shearing and tensile, respectively;

Nbs, Nbt - design forces determined by formulas 186 and 188 of SP 16.13330.2011

Friction connection calculation

Friction joints, in which forces are transmitted through friction that occurs on the contacting surfaces of the elements to be joined due to the tension of high-strength bolts, should be used: in steel structures with a yield strength of more than 375 N / mm² and directly perceiving moving, vibrational and other dynamic loads; in multi-bolt connections, which are subject to increased requirements in terms of limiting deformability.

The design force that can be taken by each friction plane of elements tightened by one high-strength bolt should be determined by formula 191 SP 16.13330.2011

where Rbh is the design tensile strength of a high-strength bolt, determined in accordance with the requirements of 6.7 of SP 16.13330.2011;

Abn is the net cross-sectional area (accepted in accordance with Table D.9 of SP 16.13330.2011);

μ is the coefficient of friction between the surfaces of the parts to be joined (accepted according to Table 42 of SP 16.13330.2011);

γh is the coefficient taken according to Table 42 of SP 16.13330.2011

The number of required bolts for friction connection can be determined by the formula 192 SP 16.13330.2011

where n is the required number of bolts;

Qbh is the design force that one bolt takes (calculated according to the formula 191 SP 16.13330.2011, described a little higher);

k is the number of friction planes of the connected elements (usually 2 elements are connected through 2 overhead plates located on different sides, in this case k = 2);

γc is the coefficient of working conditions, taken in accordance with Table 1 of SP 16.13330.2011;

γb - coefficient of working conditions, taken depending on the number of bolts required to absorb the force and taken equal to:

0.8 at n< 5;

0.9 for 5 ≤ n< 10;

1.0 for n ≤ 10.

Designation of a bolted connection in the drawings

12.1*. When designing steel structures, it is necessary:

Provide connections that ensure the stability and spatial immutability of the structure as a whole and its elements during installation and operation, assigning them depending on the main parameters of the structure and its operation mode (design scheme, spans, types of cranes and their operating modes, temperature effects, etc.). P.);

Take into account the production capabilities and capacity of technological and crane equipment of enterprises - manufacturers of steel structures, as well as lifting and transport and other equipment of installation organizations;

Carry out a breakdown of structures into shipping elements, taking into account the type of transport and dimensions of vehicles, rational and economical transportation of structures for construction and performing the maximum amount of work at the manufacturing plant;

Use the possibility of end milling for powerful compressed and eccentrically compressed elements (in the absence of significant edge tensile stresses) if the manufacturer has the appropriate equipment;

Provide for mounting fastenings of elements (arrangement of mounting tables, etc.);

In bolted mounting joints, use bolts of accuracy class B and C, as well as high-strength bolts, while in joints that perceive significant vertical forces (truss fastenings, crossbars, frames, etc.), tables should be provided; in the presence of bending moments in the joints, bolts of accuracy class B and C, working in tension, should be used.

12.2. When designing steel welded structures, the possibility of the harmful effects of residual deformations and stresses, including welding stresses, as well as stress concentration, should be excluded, providing for appropriate design solutions (with the most uniform distribution of stresses in elements and parts, without entering corners, sharp changes in cross section and other concentrators stresses) and technological measures (assembly and welding procedure, preliminary bending, machining of the corresponding zones by planing, milling, cleaning with an abrasive wheel, etc.).

12.3. In welded joints of steel structures, the possibility of brittle fracture of structures during their installation and operation as a result of an unfavorable combination of the following factors should be excluded:

high local stresses caused by concentrated loads or deformations of joint parts, as well as residual stresses;

sharp stress concentrators in areas with high local stresses and oriented across the direction of the acting tensile stresses;

low temperature at which a given steel grade, depending on its chemical composition, structure and thickness of rolled products, passes into a brittle state.

When designing welded structures, it should be taken into account that solid wall structures have fewer stress concentrators and are less sensitive to eccentricities compared to lattice structures.

12.4*. Steel structures should be protected from corrosion in accordance with SNiP for the protection of building structures from corrosion.

Protection of structures intended for operation in a tropical climate must be carried out in accordance with GOST 15150-69*.

12.5. Structures that can be exposed to molten metal (in the form of splashes when pouring metal, when metal breaks out of furnaces or ladles) should be protected by facing or enclosing walls made of refractory bricks or refractory concrete, protected from mechanical damage.

Structures exposed to prolonged exposure to radiant or convective heat or short-term exposure to fire during accidents of thermal units should be protected by suspended metal screens or brick or refractory concrete lining.

Welded joints

12.6. In structures with welded joints, you should:

Provide for the use of high-performance mechanized welding methods;

Provide free access to the places where welded joints are made, taking into account the chosen welding method and technology.

12.7. Cutting edges for welding should be taken in accordance with GOST 8713-79*, GOST 11533-75, GOST 14771-76*, GOST 23518-79, GOST 5264-80 and GOST 11534-75.

12.8. The dimensions and shape of welded fillet welds should be taken taking into account the following conditions:

a) fillet weld legs kf must be no more than 1.2t, where t is the smallest thickness of the elements to be joined;

b) the legs of the fillet welds kf should be taken according to the calculation, but not less than those indicated in Table. 38*;

c) the calculated length of the fillet weld must be at least 4kf and at least 40 mm;

d) the estimated length of the flank seam should be no more than 85? fkf (? f - coefficient taken according to Table 34 *), with the exception of seams in which the force acts throughout the seam;

e) the size of the overlap must be at least 5 thicknesses of the thinnest of the welded elements;

f) the ratio of the dimensions of the legs of the fillet welds should be taken, as a rule, 1:1. With different thicknesses of the elements to be welded, it is allowed to accept seams with unequal legs, while the leg adjacent to the thinner element must comply with the requirements of clause 12.8, a, and adjacent to the thicker element - the requirements of clause 12.8, b;

g) in structures that perceive dynamic and vibration loads, as well as those erected in climatic regions I1, I2, II2 and II3, fillet welds should be made with a smooth transition to the base metal, justified by the calculation of endurance or strength, taking into account brittle fracture.

12.9*. For attaching stiffeners, diaphragms and belts of welded I-beams according to paragraphs. 7.2*, 7.3, 13.12*, 13.26 and structures of group 4, it is allowed to use one-sided fillet welds, the legs of which kf - should be taken according to the calculation, but not less than those indicated in Table. 38*.

The use of these one-sided fillet welds is not allowed in structures:

* operated in medium-aggressive and highly aggressive environments (classification according to SNiP for the protection of building structures from corrosion);

* erected in climatic regions I1, I2, II2 and II3.

12.10. For design and structural fillet welds, the design must specify the type of welding, electrodes or welding wire, and the position of the weld during welding.

12.11. Welded butt joints of sheet parts should, as a rule, be made straight with full penetration and using lead plates.

Under installation conditions, one-sided welding with root welding and welding on the remaining steel backing is allowed.

12.12. The use of combined joints, in which part of the force is perceived by welds, and part by bolts, is not allowed.

12.13. The use of intermittent seams, as well as electric rivets, performed by manual welding with preliminary drilling of holes, is allowed only in group 4 structures.

Bolted connections and connections on high-strength bolts

12.14. Holes in the details of steel structures should be made in accordance with the requirements of SNiP according to the rules for the production and acceptance of work for metal structures.

12.15*. Accuracy class A bolts should be used for connections in which holes are drilled to the design diameter in assembled elements or along conductors in individual elements and parts, drilled or driven to a smaller diameter in separate parts, followed by reaming to the design diameter in assembled elements.

Bolts of accuracy class B and C in multi-bolt connections should be used for structures made of steel with a yield strength of up to 380 MPa (3900 kgf / cm2).

12.16. Elements in the node can be fixed with one bolt.

12.17. Bolts having sections with different diameters along the length of the uncut part are not allowed to be used in joints in which these bolts work in shear.

12.18*. Round washers according to GOST 11371-78* should be installed under the nuts of the bolts, washers should be installed under the nuts and heads of high-strength bolts according to GOST 22355-77*. For high-strength bolts in accordance with GOST 22353-77 * with increased sizes of heads and nuts and with a difference in the nominal diameters of the hole and bolt not exceeding 3 mm, and in structures made of steel with a tensile strength of at least 440 MPa (4500 kgf / cm2), not exceeding 4 mm, it is allowed to install one washer under the nut.

The thread of the shear bolt should not be more than half the thickness of the element adjacent to the nut, or more than 5 mm, except for structural structures, power transmission towers and open switchgear and transport contact lines, where the thread must be outside the package of connected elements.

Distance characteristic	Bolt spacing
1. Distances between bolt centers in any direction:
a) minimum
b) maximum in the extreme rows in the absence of bordering corners in tension and compression
c) the maximum in the middle rows, as well as in the extreme rows in the presence of bordering corners:
in tension

2. Distances from the center of the bolt to the edge of the element:
a) minimum along effort
b) the same, across the effort:
with cut edges
« rolling
c) maximum
d) minimum for high-strength bolts with any edge and any direction of force

Connecting bolts should be placed, as a rule, at maximum distances; at joints and nodes, bolts should be placed at minimum distances.

When placing bolts in a checkerboard pattern, the distance between their centers along the force should be taken at least a + 1.5d, where a is the distance between rows across the force, d is the diameter of the bolt hole. With this placement, the section of the element An is determined taking into account its weakening by holes located only in one section across the force (not along the “zigzag”).

When attaching a corner with one shelf, the hole farthest from its end should be placed at the risk closest to the butt.

12.20*. In connections with bolts of accuracy classes A, B and C (with the exception of fastening secondary structures and connections on high-strength bolts), measures must be taken against unscrewing the nuts (setting spring washers or lock nuts).

Table 35*

Characteristic connections	Connection service factor gb
1. Multi-bolt in calculations for shear and collapse with bolts:
accuracy class A
accuracy class B and C, high-strength with non-adjustable tension
2. Single-bolt and multi-bolt in terms of crushing at a = 1.5 d and b\u003d 2d in steel structural elements with a yield strength, MPa (kgf / cm 2):

St. 285 (2900) to 380 (3900)
Designations adopted in table 35*: a – distance along the force from the edge of the element to the center of the nearest hole; b - the same, between the centers of the holes; d is the diameter of the bolt hole. Notes: 1. Coefficients set in pos. 1 and 2 should be taken into account at the same time. 2. For distances a and b, intermediate between those indicated in pos. 2 in table. 39, ratio gb should be determined by linear interpolation.

For single-bolt connections, service factors must be taken into account g c in accordance with the requirements of clause 11.8.

11.8. The number n of bolts in the connection under the action of a longitudinal force N should be determined by the formula

where Nmin - the smaller of the values of the design force for one bolt, calculated in accordance with the requirements of clause 11.7* of these standards.

11.9. When a moment acts on the connection, causing a shift of the connected elements, the distribution of forces on the bolts should be taken in proportion to the distances from the center of gravity of the connection to the bolt in question.

11.10. Bolts that work simultaneously in shear and tension should be checked separately for shear and tension.

Bolts working in shear from the simultaneous action of the longitudinal force and moment should be checked for the resultant force.

11.11. In fastenings of one element to another through spacers or other intermediate elements, as well as in fastenings with a one-sided lining, the number of bolts must be increased by 10% against the calculation.

When fastening protruding shelves of corners or channels with the help of short stacks, the number of bolts attaching one of the shelves of the short stack should be increased by 50% against the calculation.

Connections on high-strength bolts

11.12. Connections on high-strength bolts should be calculated on the assumption that the forces acting in the joints and attachments are transferred through friction that occurs along the contacting planes of the connected elements from the tension of high-strength bolts. In this case, the distribution of the longitudinal force between the bolts should be taken uniform.

11.13*. Estimated force Qbh, which can be perceived by each friction surface of the connected elements, tightened by one high-strength bolt, should be determined by the formula

, (131)*

where Rbh - design tensile strength of a high-strength bolt;

m - coefficient of friction, taken according to table. 36*;

g h - reliability coefficient, taken according to Table. 36*;

A bn - net bolt cross-sectional area, determined according to Table. 62*;

gb - coefficient of connection working conditions, depending on the number n bolts necessary for the perception of the design force, and taken equal to:

0.8 at n 5;

0.9 at 5 £ n 10;

1.0 at n ³ 10.

Quantity n high-strength bolts in a joint under the action of a longitudinal force should be determined by the formula

where k

The tension of a high-strength bolt should be done with an axial force P = R bh A bn.

Table 36

Processing method	regulated	Coefficient	Odds g h under load and with a difference in the nominal diameters of holes and bolts d, mm
(cleaning) connected surfaces	tension	friction m	dynamic and d=3 – 6; static and d = 5– 6	dynamic and d=1; static and d = 1– 4
1. Shot blasting or shot blasting of two surfaces without conservation	By a
2. The same, with conservation (zinc or aluminum spray plating)	By a
3. Shot of one surface with preservation with polymer glue and sprinkling with carborundum powder, steel brushes without preservation - another surface	By a
4. Gas-plasma two surfaces without conservation	By a
5. Steel brushed two surfaces without preservation	By a
6. Without processing	By a
Notes. 1. The method of adjusting the tension of the bolts according to M means control by torque, and by a - by the angle of rotation of the nut. 2. Other methods of processing the surfaces to be joined are allowed, providing the values of the coefficients of friction m not lower than indicated in the table.

11.14. The strength calculation of the connected elements, weakened by holes for high-strength bolts, should be carried out taking into account the fact that half of the force per each bolt in the considered section has already been transferred by friction forces. In this case, the weakened sections should be checked: under dynamic loads – by net sectional area by gross sectional area BUT at An ³ 0.85A or according to the nominal area A c = 1,18A n at An 0.85A.

Connections with milled ends

11.15. In connections of elements with milled ends (at joints and bases of columns, etc.), the compressive force should be considered to be completely transmitted through the ends.

In eccentrically compressed and compressed-bent elements, welds and bolts, including high-strength ones, of these joints should be calculated for the maximum tensile force from the action of the moment and the longitudinal force with the most unfavorable combination of them, as well as for the shear force from the action of the transverse force.

Belt connections in composite beams.

11.16. Welds and high-strength bolts connecting the walls and chords of composite I-beams should be calculated according to Table. 37*.

Table 37*

Character loads	connections	Formulas for calculating belt connections in composite beams
motionless	Corner seams: bilateral	T/(2b f k f ) £ Rwfgwf g c ; (133) T/(2b z k f ) £ Rwzgwz g c (134)
	unilateral	T/(b f k f ) £ Rwfgwf g c ; (135) T/(b z k f ) £ Rwzgwz g c (136)
	High strength bolts	aT £ Q bh kg c (137)*
Movable	Fillet welds double-sided
	High strength bolts
Designations adopted in Table 37: is the shearing belt force per unit length, caused by the transverse force Q, where S is the static moment of the beam chord gross relative to the neutral axis; - pressure from a concentrated load F(for crane beams from the pressure of the crane wheel, taken without a dynamic coefficient), where g f - coefficient accepted in accordance with the requirements of SNiP for loads and impacts, lef* - the conditional length of the distribution of the concentrated load, taken according to paragraphs. 5.13 and 13.34* of these rules; a - coefficient taken at the load on the upper chord of the beam, in which the web is attached to the upper chord, a = 0.4, and in the absence of wall attachment or under load along the lower chord a = 1; a – step of belt high-strength bolts; Qbh - the design force of one high-strength bolt, determined by the formula (131) *; k is the number of friction surfaces of the connected elements.

In the absence of stiffeners for the transmission of large stationary concentrated loads, the calculation of the attachment of the upper chord should be performed as for a moving concentrated load.

When applying a stationary concentrated load to the bottom chord of the beam, welds and high-strength bolts that attach this chord to the web should be calculated using the formulas (138) - (140) * tab. 37* regardless of the presence of stiffeners in the places where the loads are applied.

Welded girdle seams, made with penetration through the entire thickness of the wall, should be considered equal strength with the wall.

11.17. In beams with connections on high-strength bolts with multi-sheet belt packages, the attachment of each of the sheets behind the place of its theoretical break should be calculated at half the force that can be perceived by the sheet section. The attachment of each sheet in the area between the actual place of its break and the place of break of the previous sheet should be calculated on the total force that can be perceived by the section of the sheet.

12. General requirements for the design of steel structures

Basic provisions

12.1*. When designing steel structures, it is necessary:

provide for connections that ensure stability and spatial immutability of the structure as a whole and its elements during installation and operation, assigning them depending on the main parameters of the structure and its operation mode (structural scheme, spans, types of cranes and their operating modes, temperature effects, etc.); P.);

take into account the production capabilities and capacity of technological and crane equipment of enterprises - manufacturers of steel structures, as well as handling and other equipment of installation organizations;

break down structures into shipping elements, taking into account the type of transport and dimensions of vehicles, rational and economical transportation of structures for construction and the implementation of the maximum amount of work at the manufacturer;

use the possibility of end milling for powerful compressed and eccentrically compressed elements (in the absence of significant edge tensile stresses) if the manufacturer has the appropriate equipment;

provide for mounting fastenings of elements (arrangement of mounting tables, etc.);

in bolted mounting joints, use bolts of accuracy class B and C, as well as high-strength ones, while in joints that perceive significant vertical forces (truss fastenings, crossbars, frames, etc.), tables should be provided; in the presence of bending moments in the joints, bolts of accuracy class B and C, working in tension, should be used.

high local stresses caused by concentrated loads or deformations of joint parts, as well as residual stresses;

sharp stress concentrators in areas with high local stresses and oriented across the direction of the acting tensile stresses;

low temperature at which a given steel grade, depending on its chemical composition, structure and thickness of rolled products, passes into a brittle state.

When designing welded structures, it should be taken into account that solid wall structures have fewer stress concentrators and are less sensitive to eccentricities compared to lattice structures.

12.4*. Steel structures should be protected from corrosion in accordance with SNiP for the protection of building structures from corrosion.

Protection of structures intended for operation in a tropical climate must be carried out according to *.

Welded joints

12.6. In structures with welded joints, you should:

provide for the use of high-performance mechanized welding methods;

provide free access to the places where welded joints are made, taking into account the selected welding method and technology.

12.7. Cutting edges for welding should be taken in accordance with GOST 8713 – 79*, GOST 11533 - 75, *, and GOST 11534 – 75.

12.8. The dimensions and shape of welded fillet welds should be taken taking into account the following conditions:

a) legs of fillet welds kf should be no more than 1.2 t, where t - the smallest thickness of the connected elements;

b) legs of fillet welds kf should be taken according to the calculation, but not less than those indicated in Table. 38*;

c) the calculated length of the fillet weld must be at least 4 kf and not less than 40 mm;

d) the estimated length of the flank seam should be no more than 85 b f k f (b f - the coefficient taken according to the table. 34 *), with the exception of seams in which the force acts throughout the seam;

e) the size of the overlap must be at least 5 thicknesses of the thinnest of the welded elements;

g) in structures that perceive dynamic and vibration loads, as well as those built in climatic regions I 1, I 2, II 2 and II 3, fillet welds should be made with a smooth transition to the base metal when justified by the calculation of endurance or strength, taking into account brittle destruction.

Table 38*

Connection type		yield strength of steel,	Minimum leg seams kf, mm, with the thickness of the thicker of the welded elements t, mm
		MPa (kgf / cm 2)	4– 6	6– 10	11– 16	17– 22	23– 32	33– 40	41– 80
Tavrovoe with two hundred
front corner seams; overlap-		St. 430 (4400)
precise and angular	Automatic and
	semi-automatic	St. 430 (4400)
Tavrovoe with
one-sided fillet welds	Automatic and semi-automatic
Notes: 1. In structures made of steel with a yield strength of more than 530 MPa (5400 kgf / cm 2), as well as of all steels with an element thickness of more than 80 mm, minimum fillet weld legs are accepted according to special specifications. 2. In group 4 structures, the minimum legs of one-sided fillet welds should be reduced by 1 mm for the thickness of the welded elements up to 40 mm inclusive. and 2 mm – with the thickness of the elements over 40 mm.

12.9*. For attaching stiffeners, diaphragms and belts of welded I-beams according to paragraphs. 7.2*, 7.3, 13.12*, 13.26 and structures of group 4, it is allowed to use one-sided fillet welds, the legs of which kf should be taken according to the calculation, but not less than those indicated in Table. 38*.

The use of these one-sided fillet welds is not allowed in structures:

operated in medium-aggressive and highly aggressive environments (classification according to SNiP for the protection of building structures from corrosion);

erected in climatic regions I 1 , I 2 , II 2 and II 3 .

12.10. For design and structural fillet welds, the design must specify the type of welding, electrodes or welding wire, and the position of the weld during welding.

12.11. Welded butt joints of sheet parts should, as a rule, be made straight with full penetration and using lead plates.

Under installation conditions, one-sided welding with root welding and welding on the remaining steel backing is allowed.

12.12. The use of combined joints, in which part of the force is perceived by welds, and part – bolts, not allowed.

12.13. The use of intermittent seams, as well as electric rivets, performed by manual welding with preliminary drilling of holes, is allowed only in group 4 structures.

Bolted connections and connections on high-strength bolts

12.14. Holes in the details of steel structures should be made in accordance with the requirements of SNiP according to the rules for the production and acceptance of work for metal structures.

Bolts of accuracy class B and C in multi-bolt connections should be used for structures made of steel with a yield strength of up to 380 MPa (3900 kgf / cm 2).

12.16. Elements in the node can be fixed with one bolt.

12.17. Bolts having sections with different diameters along the length of the uncut part are not allowed to be used in joints in which these bolts work in shear.

12.18*. Under the nuts of the bolts, round washers should be installed in accordance with GOST 11371 – 78*, under nuts and heads of high-strength bolts, washers should be installed according to *. For high-strength bolts * with increased sizes of heads and nuts and with a difference in the nominal diameters of the hole and the bolt not exceeding 3 mm, and in structures made of steel with a tensile strength of at least 440 MPa (4500 kgf / cm 2), not exceeding 4 mm, it is allowed to install one washer under the nut.

12.19*. Bolts (including high-strength ones) should be placed in accordance with Table. 39.

Table 39

Distance characteristic	Bolt spacing
1. Distances between bolt centers in any direction: a) minimum
b) maximum in the extreme rows in the absence of bordering corners in tension and compression	8d or 12 t
c) the maximum in the middle rows, as well as in the extreme rows in the presence of bordering corners:
in tension	16d or 24 t
under compression	12d or 18 t
2. Distances from the center of the bolt to the edge of the element:
a) minimum along effort
b) the same, across the effort:
with cut edges
with rolling edges
c) maximum	4d or 8 t
d) minimum for high-strength bolts with any edge and any direction of force
* In connected elements made of steel with a yield strength of more than 380 MPa (3900 kgf / cm 2), the minimum distance between the bolts should be taken equal to 3 d. Designations adopted in table 39: d - diameter of the hole for the bolt; t is the thickness of the thinnest outer element. Note. In connected elements made of steel with a yield strength of up to 380 MPa (3900 kgf / cm 2), it is allowed to reduce the distance from the center of the bolt to the edge of the element along the force and the minimum distance between the centers of the bolts in cases of calculation taking into account the relevant coefficients of the operating conditions of the joints in accordance with paragraphs. 11.7* and 15.14*.

Connecting bolts should be placed, as a rule, at maximum distances, at joints and nodes, bolts should be placed at minimum distances.

When placing bolts in a checkerboard pattern, the distance between their centers along the force should be taken at least a + 1,5d, where a - distance between rows across the force, d is the diameter of the bolt hole. With this arrangement, the section of the element A n is determined taking into account its weakening by holes located only in one section across the force (not along the "zigzag").

When attaching a corner with one shelf, the hole farthest from its end should be placed at the risk closest to the butt.

13. Additional requirements for the design of industrial buildings and structures 1

Relative deflections and deviations of structures

13.1*. Deflections and displacements of structural elements should not exceed the limit values established by SNiP for loads and impacts.

Tab. 40* is excluded.

13.2– 13.4 and Table 41* are excluded.

1 It is allowed to apply to other types of buildings and structures.

Distances between expansion joints

13.5. The greatest distances between the expansion joints of steel frames of one-story buildings and structures should be taken according to Table. 42.

When exceeding more than 5% of those indicated in Table. 42 distances, as well as with an increase in the rigidity of the frame by walls or other structures, the calculation should take into account climatic temperature effects, inelastic deformations of structures and compliance of nodes.

Table 42

	The greatest distances, m
	expansion joints				from the expansion joint or the end of the building to the axis of the nearest
Building characteristics and facilities	along the length of the block (along the building)		by block width		vertical connection
	in climatic areas of construction
		I 1 , I 2 , II 2 and II 3	all except I 1 , I 2 , II 2 and II 3	I 1 , I 2 , II 2 and II 3	all except I 1 , I 2 , II 2 and II 3	I 1 , I 2 , II 2 and II 3
Heated buildings
Unheated buildings and hot shops
Open flyovers			–	–
Note. If there are two vertical connections between the expansion joints of a building or structure, the distance between the latter in the axes should not exceed: for buildings – 40– 50 m and for open flyovers – 25- 30 m, while for buildings and structures erected in climatic regions I 1, I 2, II 2 and II 3, the smaller of the indicated distances should be taken.

Farms and structural

coating slabs

13.6. The axes of the bars of trusses and structures should, as a rule, be centered at all nodes. The centering of the rods should be carried out in welded trusses according to the centers of gravity of the sections (with rounding up to 5 mm), and in bolted - according to the risks of the corners closest to the butt.

The displacement of the axes of the truss chords when changing the sections may not be taken into account if it does not exceed 1.5% of the height of the chord.

In the presence of eccentricities at the nodes, the elements of trusses and structures should be calculated taking into account the corresponding bending moments.

When loads are applied outside the truss nodes, the chords must be designed for the combined action of longitudinal forces and bending moments.

13.7. When spanning roof trusses over 36 m, a construction lift equal to the deflection from constant and long-term loads should be provided. For flat roofs, construction lifting should be provided regardless of the span, taking it equal to the deflection from the total standard load plus 1/200 of the span.

13.8. When calculating trusses with elements from corners or tees, the connections of elements in the truss nodes can be taken as hinged. With I-beam, H-shaped and tubular sections of elements, the calculation of trusses according to the hinged scheme is allowed when the ratio of the height of the section to the length of the elements does not exceed: 1/10 - for structures operated in all climatic regions, except for I 1, I 2, II 2 and II 3; 1/15 – in regions I 1 , I 2 , II 2 and II 3 .

If these ratios are exceeded, additional bending moments in the elements due to the rigidity of the nodes should be taken into account. It is allowed to take into account the stiffness of nodes in trusses by approximate methods; axial forces are allowed to be determined according to the hinged scheme.

13.9*. The distance between the edges of the elements of the lattice and the belt in the nodes of welded trusses with gussets should be taken at least a = 6t – 20 mm, but not more than 80 mm (here t – gusset thickness, mm).

A gap of at least 50 mm should be left between the ends of the joined elements of the truss belts, overlapped by overlays.

The welds that attach the elements of the truss lattice to the gussets should be brought to the end of the element to a length of 20 mm.

13.10. In truss nodes with belts made of T-beams, I-beams and single corners, fastening of gussets to the shelves of the belts end-to-end should be carried out with penetration through the entire thickness of the gusset. In designs of group 1, as well as those operated in climatic regions I 1, I 2, II 2 and II 3, the junction of nodal gussets to the belts should be performed in accordance with pos. 7 table 83*.

columns

13.11. The sending elements of through columns with gratings in two planes should be reinforced with diaphragms located at the ends of the sending element.

In through columns with a connecting grid in the same plane, the diaphragms should be located at least 4 m apart.

13.12*. In centrally compressed columns and racks with one-sided girdle seams in accordance with clause 12.9 * in the attachment points of braces, beams, struts and other elements in the force transfer zone, two-sided girdle seams should be used that extend beyond the contours of the attached element (node) by a length of 30 kf from each side.

13.13. Fillet welds attaching the gussets of the connecting grid to the overlapping columns should be assigned according to the calculation and placed on both sides of the gusset along the column in the form of separate sections in a checkerboard pattern, while the distance between the ends of such seams should not exceed 15 gusset thicknesses.

In structures erected in climatic regions I 1, I 2, II 2 and II 3, as well as when using manual arc welding, the seams must be continuous along the entire length of the gusset.

13.14. Assembly joints of columns should be made with milled ends, butt-welded, on overlays with welded seams or bolts, including high-strength ones. When welding overlays, the seams should not be brought to the joint by 30 mm on each side. It is allowed to use flange connections with the transfer of compressive forces through a tight touch, and tensile - bolts.

Connections

13.15. In each temperature block of the building, an independent system of connections should be provided.

13.16. The lower chords of crane beams and trusses with a span of more than 12 m should be reinforced with horizontal braces.

13.17. Vertical connections between the main columns below the level of crane beams with two-branch columns should be located in the plane of each of the branches of the column.

The branches of two-branch connections, as a rule, should be interconnected by connecting grids.

13.18. Transverse horizontal connections should be provided at the level of the upper or lower chords of roof trusses in each span of the building along the ends of the temperature blocks. If the length of the temperature block is more than 144 m, intermediate transverse horizontal braces should be provided.

Rafter trusses that are not directly adjacent to the cross braces should be braced in the plane of the location of these braces with spacers and stretch marks.

At the locations of the cross-links, vertical links between the trusses should be provided.

In the presence of a hard disk of the roof at the level of the upper chords, removable inventory ties should be provided to align the structures and ensure their stability during installation.

In the coatings of buildings and structures operated in climatic regions I 1, I 2, II 2 and II 3, as a rule, vertical ties should be provided (in addition to those usually used) in the middle of each span along the entire building.

13.19*. Longitudinal horizontal connections in the plane of the lower chords of roof trusses should be provided along the extreme rows of columns in buildings with cranes of operating mode groups 6K - 8K by ; in coverings with truss trusses; in one- and two-span buildings with overhead cranes with a lifting capacity of 10 tons or more, and with a mark of the bottom of the truss structures over 18 m – regardless of the lifting capacity of the cranes.

In buildings with more than three spans, horizontal longitudinal ties should also be placed along the middle rows of columns at least through the span in buildings with cranes of operating mode groups 6K – 8K over and over two spans in other buildings.

13.20. Horizontal connections along the upper and lower chords of split trusses of spans of conveyor galleries should be designed separately for each span.

13.21. When using a cross lattice of coating ties, calculation is allowed according to a conditional scheme on the assumption that the braces perceive only tensile forces.

When determining the forces in the elements of the connections, the compression of the truss chords, as a rule, should not be taken into account.

13.22. When installing a membrane deck in the plane of the lower chords of trusses, it is allowed to take into account the operation of the membrane.

13.23. In hanging pavements with planar bearing systems (double-zone, flexural-rigid guys, etc.), vertical and horizontal connections between the bearing systems should be provided.

beams

13.24. The use of sheet packs for chords of welded I-beams is generally not allowed.

For beam chords on high-strength bolts, it is allowed to use packages consisting of no more than three sheets, while the area of the waist corners should be taken equal to at least 30% of the entire area of the chord.

13.25. Belt seams of welded beams, as well as seams that attach auxiliary elements to the main beam section (for example, stiffeners), must be continuous.

13.26. When using one-sided belt welds in welded I-beams bearing a static load, the following requirements must be met:

design load must be applied symmetrically with respect to the cross section of the beam;

the stability of the compressed beam chord must be ensured in accordance with clause 5.16*, a;

in places where concentrated loads are applied to the beam chord, including loads from ribbed reinforced concrete slabs, transverse stiffeners should be installed.

In the crossbars of frame structures at the support nodes, two-sided waist seams should be used.

In beams calculated in accordance with the requirements of paragraphs. 5.18* - 5.23 of these standards, the use of one-sided waist seams is not allowed.

13.27. The stiffeners of welded beams must be removed from the wall joints at a distance of at least 10 wall thicknesses. At the intersection of the butt welds of the beam web with a longitudinal stiffener, the seams attaching the rib to the web should not be extended to the butt weld by 40 mm.

13.28. In welded I-beams of structures of groups 2 - 4, as a rule, one-sided stiffeners should be used with their location on one side of the beam.

In beams with one-sided waist welds, stiffeners should be located on the side of the web opposite to the location of one-sided waist welds.

Crane beams

13.29. The strength analysis of crane beams should be performed in accordance with the requirements of clause 5.17 for the effect of vertical and horizontal loads.

13.30*. The calculation of the strength of the walls of crane beams (with the exception of beams calculated for endurance, for cranes of the operating mode groups 7K in the shops of metallurgical production and 8K according to ) should be performed according to formula (33), in which, when calculating the sections on the supports of continuous beams, instead of the coefficient 1, 15 should take the coefficient 1.3.

13.31. Calculation for the stability of crane beams should be carried out in accordance with paragraph 5.15.

13.32. Checking the stability of the walls and belt sheets of crane beams should be carried out in accordance with the requirements of Sec. 7 of these rules.

13.33*. Crane beams should be calculated for endurance in accordance with Sec. 9 of these standards, while taking into account a = 0.77 with cranes of operating mode groups 7K (in metallurgical production shops) and 8K according to and a = 1.1 in other cases.

In crane beams for cranes of operating mode groups 7K (in metallurgical plants) and 8K along the walls, additionally, strength should be calculated in accordance with clause 13.34* and endurance in accordance with clause 13.35*.

Accordingly, the bending moment and the transverse force in the beam section from the design load;

g f 1 - coefficient of increase in the vertical concentrated load on an individual crane wheel, taken in accordance with the requirements of SNiP for loads and impacts;

F - design pressure of the crane wheel without taking into account the dynamic factor;

lef - conditional length, determined by the formula

where with - coefficient accepted for welded and rolled beams 3.25, for beams on high-strength bolts – 4,5;

J 1f - the sum of the own moments of inertia of the chord of the beam and the crane rail or the total moment of inertia of the rail and chord in the case of welding the rail with seams that ensure the joint operation of the rail and the chord;

M t - local torque, determined by the formula

M t = Fe + 0,75 Q t h r, (147)

where e - conditional eccentricity, taken equal to 15 mm;

Q t - transverse design horizontal load caused by distortions of the overhead crane and non-parallelism of crane tracks, taken in accordance with the requirements of SNiP for loads and impacts;

hr – crane rail height;

is the sum of the own moments of inertia of torsion of the rail and belt, where t f and b f are the thickness and width of the upper (compressed) chord of the beam, respectively.

All stresses in formulas (141) – (145)* should be taken with a plus sign.

13.35*. The calculation for endurance of the upper zone of the wall of a composite crane beam should be performed according to the formula

where Rn - design fatigue resistance for all steels, taken equal, respectively, for welded beams and high-strength bolts: Rn \u003d 75 MPa (765 kgf / cm 2) and 95 MPa (930 kgf / cm 2) for the compressed upper zone of the wall (section in the span of the beam); Rn \u003d 65 MPa (665 kgf / cm 2) and 89 MPa (875 kgf / cm 2) for the tensioned upper zone of the wall (supporting sections of continuous beams).

The stress values in formula (148) should be determined according to clause 13.34 * from crane loads, established in accordance with the requirements of SNiP for loads and effects.

The upper waist seams in the crane beams for cranes of the operating mode groups 7K (in the shops of metallurgical production) and 8K must be made with penetration through the entire thickness of the wall.

13.36. The free edges of the stretched chords of crane beams and beams of working platforms that directly perceive the load from rolling stock must be rolled, planed or cut by machine oxygen or plasma-arc cutting.

13.37*. The dimensions of the stiffeners of the crane beams must meet the requirements of clause 7.10, while the width of the protruding part of the double-sided rib must be at least 90 mm. Bilateral transverse stiffeners must not be welded to beam chords. The ends of the stiffeners must be tightly fitted to the upper chord of the beam; at the same time, in the beams under the cranes of the operating mode groups 7K (in the shops of metallurgical production) and 8K, it is necessary to plan the ends adjacent to the upper belt.

In beams for cranes of groups of operating modes 1K - 5K, it is allowed to use one-sided transverse stiffeners with their welding to the wall and to the upper chord and location in accordance with clause 13.28.

13.38. The strength calculation of suspension beams of crane rails (monorails) should be performed taking into account local normal stresses at the site of application of pressure from the crane wheel, directed along and across the axis of the beam.

Sheet structures

13.39. The contour of the transverse stiffeners of shells should be designed closed.

13.40. The transfer of concentrated loads to sheet structures should, as a rule, be provided through stiffeners.

13.41. In places where shells of various shapes are joined, as a rule, smooth transitions should be used in order to reduce local stresses.

13.42. All butt welds should be provided either by double-sided welding, or by one-sided welding with root or backing welding.

The project should indicate the need to ensure the tightness of the joints of structures in which this tightness is required.

13.43. In sheet structures, as a rule, butt welded joints should be used. Joints of sheets with a thickness of 5 mm or less, as well as field joints, may be overlapped.

13.44. When designing sheet structures, it is necessary to provide for industrial methods for their manufacture and installation by using:

sheets and tapes of large sizes;

method of rolling, manufacturing blanks in the form of shells, etc.;

cutting, providing the least amount of waste;

automatic welding;

the minimum number of welds performed on installation.

13.45. When designing rectangular or square in terms of flat membranes, at the corners of the supporting contours, as a rule, smooth conjugation of the contour elements should be used. For membrane structures, as a rule, steels with increased resistance to corrosion should be used.

Mounting fasteners

13.46*. Mounting fastenings of structures of buildings and structures with crane beams calculated for endurance, as well as structures for railway trains, should be carried out on welding or high-strength bolts.

Bolts of accuracy classes B and C in field connections of these structures can be used:

for fastening purlins, elements of a lantern structure, ties along the upper chords of trusses (if there are ties along the lower chords or a rigid roof), vertical ties along trusses and lanterns, as well as fachwerk elements;

for fastening ties along the lower chords of trusses in the presence of a rigid roof (reinforced concrete or reinforced slabs made of cellular concrete, steel profiled flooring, etc.);

for fastening truss and truss trusses to columns and truss trusses to truss trusses, provided that the vertical support pressure is transmitted through the table;

for attaching split crane beams to each other, as well as for attaching their lower chord to columns to which vertical connections are not attached;

for fixing beams of working platforms that are not exposed to dynamic loads;

for fastening secondary structures.

14. Additional requirements for the design of residential and public buildings and structures

Frame buildings

14.1- 14.3 and tab. 43 are excluded.

14.4*. To redistribute bending moments in the elements of frame systems, it is allowed to use steel plates in the joints of crossbars with columns, working in the plastic stage.

Linings should be made of steels with a yield strength of up to 345 MPa (3500 kgf / cm 2).

The forces in the pads should be determined at a minimum yield strength s y,min = Ryn and maximum yield strength s y,max = Ryn+ 100 MPa (1000 kgf / cm 2).

Linings working in the plastic stage must have planed or milled longitudinal edges.

Hanging covers

14.5. For filament structures, as a rule, ropes, strands and high-strength wire should be used. rental is allowed.

14.6. The roof of a hanging covering, as a rule, should be located directly on the bearing threads and repeat the shape they form. It is allowed to raise the roof above the threads, leaning on a special superstructure, or hang it from below to the threads. In this case, the shape of the roof may differ from the shape of the sagging threads.

14.7. The outlines of the support contours should be assigned taking into account the pressure curves from the forces in the threads attached to them under design loads.

14.8. Hanging roofs should be relied upon for form stability against temporary loads, including from wind suction, which should ensure the tightness of the adopted roof structure. In this case, it is necessary to check the change in the curvature of the coating in two directions - along and across the threads. The necessary stability is achieved with the help of constructive measures: increasing the tension of the thread due to the weight of the coating or prestressing; creation of a special stabilizing structure; the use of flexurally rigid threads; the transformation of the system of threads and roofing slabs into a single structure.

14.9. The cross section of the thread should be calculated according to the greatest force that occurs at the design load, taking into account changes in the specified coating geometry. In mesh systems, in addition, the cross section of the thread must be checked for force from the action of a live load located only along this thread.

14.10. The vertical and horizontal movements of the threads and the forces in them should be determined taking into account the nonlinearity of the coating structures.

14.11. The coefficients of the operating conditions of threads from ropes and their fastenings should be taken in accordance with Sec. 16. For stabilizing ropes, if they are not puffs for the support loop, the service factor g c = 1.

14.12. The support knots of threads from rolled profiles should be made, as a rule, hinged.

fifteen*. Additional requirements for the design of supports for overhead power lines, structures of open switchgear and lines of contact networks of transport

15.1*. For supports of overhead power lines (VL) and structures of open switchgears (OSG) and lines of contact networks of transport (CS), as a rule, steels should be used in accordance with Table. 50* (except for steels С390, С390К, С440, С590, С590К) and tab. 51, a.

15.2*. Bolts of accuracy classes A, B and C for overhead line supports and outdoor switchgear structures up to 100 m high should be taken as for structures that are not designed for endurance, and for supports more than 100 m high - as for structures designed for endurance.

15.3. Cast parts should be designed from carbon steel grades 35L and 45L of casting groups II and III in accordance with GOST 977 – 75*.

15.4*. When calculating the supports of overhead lines and the structures of outdoor switchgear and CS, the coefficients of working conditions established by Sec. 4* and 11, as well as according to the table. 44*, para. 15.14* and adj. 4* of these standards.

The strength calculation of the support elements, with the exception of the calculation of sections in the places of fastening of tensioned elements from single corners, attached by one shelf with bolts, according to clause 5.2 is not allowed.

Table 44*

Structural elements	Working conditions coefficients g with
1. Compressed belts from single corners of racks of free-standing supports in the first two panels from the shoe at nodal connections
a) welding
b) on bolts
2. Compressed elements of flat lattice traverses from single equal-shelf corners attached by one shelf (Fig. 21):
a) belts attached to the support post directly with two or more bolts
b) belts attached to the support post with one bolt or through a gusset
c) braces and struts
3. Guys from steel ropes and bundles of high-strength wire:
a) for intermediate supports in normal operating modes
b) for anchor, anchor-angle and corner supports:
in normal operating conditions
in emergency operation
Note: The coefficients of working conditions indicated in the table do not apply to the connections of elements in nodes.

table 2

Distance characteristic	Value
Distances between bolt centers in any direction:
a) minimum (for steel with 380 MPa)	2.5d
b) the maximum in the extreme rows in the absence of fringing
corners	8d or 12t
in) maximum in the middle rows, as well as in the outer rows with
the presence of bordering corners:
in tension	16d or 24t
under compression	12d or 18t
Distance from the center of the bolt to the edge of the element:
a) minimum effort per day	2d
b) the same, across the effort at the edges:
edged	1.5d
rolling	1.2d
c) maximum	4d or 8t
d) minimum for high-strength bolts at any edge and
any direction of effort	1.3d

Note:

d- bolt hole diameter; / - the thickness of the thinnest outer element. Connecting bolts should be placed at maximum distances, and at joints and knots, bolts should be placed at minimum distances.

Ultimate bolt force Table 3
Characteristics of bolts and connections	Class	stressed state	Force, tf, for bolt diameter, mm

using the cross section (net). cm 2
0,83	1,57	2,45	3,52	5,60
Single-bolt and multi-bolt with bolts of normal accuracy	4,6	stretching	1,46	2,74	4,28	6,16	9,80
5,6	1,75	3,30	5,14	7,39	11,76
6,6	2,09	3,92	6,12	8,80	14,00
Single bolt with bolts of normal accuracy	4,6	slice	1,70	3,01	4,71	6,78	10,80
5,6	2,15	3,80	5,96	8,50	13,40
	Collapse*	4,92	6,56	8,20	9,84	12,30
Multi-bolt with bolts of normal accuracy	4,6	slice	1,30	2,30	3,60	5,19	8,11
5,6	1,64	2,92	4,56	6,56	10,26
8,8	2,76	4,92	7,68	11,06	17,28
	Collapse	3,76	5,02	6,27	7,52	9,41
Single-bolt and multi-bolt with high precision bolts	8,8	stretching	3,35	6,28	9,80	14,08	22,40
	slice	3,07	5,46	8,54	12,29	19,20
	Collapse	-	6,12	7,65	9,18	11,47

Note:

* With a thickness of the crushed element of 1 cm in steel structures with a yield strength of up to 250 MPa (3550 kgf / cm 2).

REFERENCES

1. GOST 20850-84. Constructions wooden glued. General specifications.

2. GOST 8486-86*E. Softwood lumber. Specifications.

3. GOST 2695-83*. Hardwood lumber. Specifications.

4. GOST 24454-80*E. Softwood lumber. Dimensions.

5. GOST 16363-98. Means of protection for wood. Method for determining fire-retardant properties.

6. GOST 6449.1-82. Products from wood and wood materials. Tolerance fields for linear dimensions and fit.

7. GOST 7307-75*. Details made of wood and wood-based materials. Allowances for machining.

8. SNiP 52-01-2003. Concrete and reinforced concrete structures / Gosstroy RF. - M. : Gosstroy of Russia, 2004. - 79 p.

9. SNiP 21-01-97*. Fire safety of buildings and structures. -M.: Ministry of Construction of Russia, 2002. - 15 p.

10. SNiP 3.03.01-87. Bearing and enclosing structures. - M.: Stroyizdat, 1989. - 90 p.

11. SP 64.133302011. Wooden structures. Updated edition of SNiP II-25-80.-M.: Ministry of Regional Development, 2010.-86 p.

12. SP 20.133302011. Loads and impacts. Updated version of SNiP 2.01.07-85.-M.: Ministry of Regional Development, 2010.-86 p.

13. Benefit for the design of wooden structures (to SNiP P-25-80). - M.: Stroyizdat, 1986-215 p.

19. Management for the manufacture and quality control of wooden glued structures. –M.: Stroyizdat, 1982.-79 p.

20. Management for the design of glued wooden structures. -M.: Stroyizdat, 1977.-189 p.

21. Management to ensure the durability of wooden glued structures when exposed to the microclimate of buildings for various purposes and atmospheric factors. – M.: Stroyizdat, 1981.-96 p.

22. Directions on the use of wooden structures in a chemically aggressive environment. –M.: Stroyizdat, 1969.-70s.

23. Ashkenazi E.K. Anisotropy of structural materials: reference book / E.K. Ashkenazi, E.V. Ganov.-L.: Engineering, 19080.-247p.

24. Vetryuk, I. M. Structures made of wood and plastics / I. M. Vetryuk. - Minsk: Higher School, 1973. - 336 p.

25. Grin,And.M. Building structures made of wood and synthetic materials: Design and calculation: textbook / I.M. Grin, K.E. Dzhantemirov, V.I. Grin. ed. 3rd, revised and additional. - Kyiv: Vishcha school, 1990. - 221 p.

26. . Wooden structures: Handbook of the designer of industrial structures. - M.; L.:ONTI, 1937.-955 p.

27. Dmitriev, P. A. Non-metal structures: textbook. allowance / P. A. Dmitriev, Yu. D. Strizhakov. - Novosibirsk: NISI, 1982. - 80 p.

28.Zubarev, G. N. Structures made of wood and plastics: textbook. allowance / G. N. Zubarev, I. M. Lyalin.-M .: Higher School, 1980. - 311 p.

29. Zubarev, G.N. Structures made of wood and plastics / G.N. Zubarev. – M.: Vyssh.shk., 1990.-287 p.

30. Ivanov, V. A. Constructions made of wood and plastics / V. A. Ivanov, V. Z. Klimenko. - Kyiv: Vishcha school, 1983. - 279 p.

31. Ivanin, I. Ya. Wooden structures. Calculation examples / I. Ya. Ivanin. - M., 1950. - 224 p.

Ivanov V.F. Structures made of wood and plastics / Ivanov V.F .. - M .; L ..: Stroyizdat, 1966.-352 p.
Ivanov V.A. Structures made of wood and plastics: Examples of calculation and design / Ed. V.A. Ivanova, - Kyiv: Vishcha school, 1981.- 392 p.
Kalugin A.V. Wooden structures: textbook. Manual (lecture notes) / A.V. Kalugin.-M: DIA, 2003.-224 p.
Carlsen G.G. Industrial wooden structures: Design examples / Ed. G.G. Carlsen. –M.: Stroyizdat, 1967.-320 p.
Carlsen G.G. Structures made of wood and plastics / Ed. G.G. Carlsen. 4th ed. M.: Stroyizdat, 1975.- 688 p.
Kovalchuk, L. M. Wooden structures in construction / L. M. Kovalchuk, S. B. Turkovsky and others - M .: Stroyizdat, 1995. - 248 p.
Lomakin A.D. Protection of wooden structures / Lomakin A.D. - M .: LLC RIF "Stroymaterialy" 2013.- 424p. ISBN 978-5-94026-024-0

39. Otreshko, A. I. Designer's Handbook. Wooden structures / A. I. Otreshko. -M.: Stroyizdat, 1957.-263 p.

40. Svetozarova, E. I. Structures made of glued wood and waterproof plywood. Design examples: textbook. allowance / E. I. Svetozarova, S. A. Dushechkin, E. N. Serov. - L.: LISI, 1974. -133 p.

41. Serov E.N. Design of wooden structures: study guide / E.N. Serov, Yu.D. Sannikov, A.E. Serov; ed. E.N. Serova; - M.: Izd-vo ASV, 2011. -536s. ISBN 978-5-9227-0236-2; ISBN 978-5-93093-793-0

42. Serov, E. N. Design of glued wooden structures: textbook. allowance. Part 1. Design of beams and racks of frame buildings / E. N. Serov, Yu. D. Sannikov / / St. Petersburg: SPbGASU, 1995. - 140s; Ch. P. Designing frames from rectilinear elements / St. Petersburg: SPbGASU, 1998. - 133 p.; Part III. Designing frames with curved sections and arches / St. Petersburg: SPbGASU, 1999. - 160 p.

Svetozarova E.I. Structures from glued wood and waterproof plywood: Design examples / Svetozarova E.I. ., Dushechkin S.A., Serov E.N. - L.: LISI, 1974.- 134 p.

44. Slitskoukhov, Yu. V. Industrial wooden structures. Design examples / Yu. V. Slitskoukhov and others - M .: Stroyizdat, 1991. - 256 p.

45. Slitskoukhov Yu.V. Structures made of wood and plastics: textbook. for universities / Yu.V. Slitskoukhov [and others]; ed. G.G. Carlsen, Yu.V. Slitskoukhov, - Ed.5th, revised. and additional –M.: Stroyizdat, 1986.-547 p.

46. V.V. Stoyanov. Structures made of wood and plastics / V.V. Stoyanov: Lecture notes, part 1. OGAS Publishing House, 2005.-157p.

47. V.V. Stoyanov. Structures made of wood and plastics / V.V. Stoyanov: Lecture notes, part 2. Publishing house of LLC "Vneshreklamservis", 2005.- 136p.

48. Turkovsky S.B. Glued wooden structures with knots on glued rods in modern construction (TsNIISK System) / under the general editorship of S.B. Turkovsky and I.P. Preobrazhenskaya.- M.; RIF "Building materials" 2013.-308s.

49. Schmid, A. B. Atlas of building structures made of glued wood and waterproof plywood: textbook. Allowance / A.B. Shmd, P.A. Dmitriev.-M.: Publishing House of the Association builds. Vuzov, 2001.- 292 p.- ISBN 5-274-00419-9.

50. Guidelines for the course project on the discipline "Designs made of wood and plastics" / Vladim. State. un-t; E.A. Smirnov, S.I. Roshchina, M.V. Gryaznov.-Vladimir: VlSU Publishing House, 2012. - 56p.

51. Guidelines for the course project "One-story frame building" in the discipline "Structures made of wood and plastic" / ALTI; B.V. Labudin, N.P. Kovalenko.-Arkhangelsk: Publishing house ALTI, 1983. - 28s.

52. Guidelines for the implementation of the course project for the course "Structures made of wood and plastic" / LISI; Yu.S. Ovchinnikov.-L: LISI Publishing House, 1977.–42s

1.	THEME AND SCOPE OF THE COURSE PROJECT…………………………….
2.	DESIGN ASSIGNMENT……………………………………
3.	LAYOUT PART OF THE TECHNICAL PROJECT…………
4.	GENERAL PROVISIONS FOR THE PROJECT…………………………………
5.	REQUIREMENTS FOR STRUCTURAL MATERIALS………………….
6.	CALCULATED CHARACTERISTICS OF MATERIALS………………….
	APPENDICES……………………………………………………………
	EXAMPLE OF GRAPHIC DESIGN OF A COURSE PROJECT
	BIBLIOGRAPHICAL LIST…………………………………….

Labudin Boris Vasilievich

Guryev Alexander Yurievich

DESIGNS

WOOD AND PLASTIC

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