Bolted joints on high strength bolts. Steel building structures. mounting joints on high strength bolts. typical technological process. Connection recovery technology

Orlen Labor Red Banner Central Research and Design Institute of Building Metal Structures (TsNII11roektstalkonstruktsiya)

Gosstroy of the USSR

Guide

and standards for production technology high strength bolts

in assembly

compounds

metalwork

Moscow Stroyizdat 1982

Guidelines and guidelines for technology for setting high-strength bolts in mounting connections  metalwork / Central Research Institute of Design Steel Construction USSR Gosstroy. - M.: Stroyedat, 1982.- 92 p.

Developed for the chapter SNiP Sh-18-75 "Metal structures. Rules for the production and acceptance of work."

Issues related to the features of the technology for assembling joints, setting and tensioning high-strength bolts during the installation of steel building structures are considered. In addition to traditional hard-wearing joints, joints with load-bearing high-strength bolts, bolt-glue, glue-friction, bolt-rivet and bolt-welded joints are considered. The proposal is the most technologically advanced methods of surface preparation of construction, methods of adjusting the tension of bolts with pneumatic and electric wrenches.

For engineers and technicians and installers who perform connections on high-strength bolts.

Tab. 21, ill. 20.

Iistrukt.-Iormat., P vyl. - 109-81

i J2Q№ (No. 1 ~ JU2-

© Stroynadat, 1982

FOREWORD

The manual was developed by TsNIIProektstalkon-structure of Gosstroy of the USSR with the participation of Dneproproject-steel construction, VNIPILromstalkonstruktsiya and MADI to the chapter SNiP Sh-18-75 "Metal structures. Rules for the production and acceptance of work" instead of the Guidelines for the implementation of shear-resistant joints on high-strength bolts in building steel structures "( M., Stroyizdat,

In the development of the Guide took part: engineers V.M.Babushkin, V.P. Velikhov, Ph.D. tech. Sciences 8.V. Volkov, Dr. tech. sciences, prof. N.N. Streletsky, engineer S.0.Chizhov (TsNIIProektstalkonstruktsiya), Ph.D. tech. Sciences I.I. Vishnevsky ^ non-project steel construction), candidates of tech. Sciences V.V. Kalenov, A.F. Knyazhev (VNIIpromstalkonstruktsiya), Ph.D. tech. Sciences, Associate Professor B.M. Weinblat (MADI).

When developing the Guidelines, the results of the KievNIL TSNIIS research work on the technology for the implementation of adhesive compounds were taken into account.

For all questions, please contact: 117393, Moscow, Novye Cheryomushki, block 28, building. 2, TsNIIProektstalkonstruktsiya, tel. 128-57 ~ 7b.

1. GENERAL PROVISIONS

1.1. This Guide has been developed in the development of the chapter SNiP 111-18-75 "Metal structures. Rules for the production and acceptance of work" in terms of the technology for mounting joints on high-strength bolts in steel structures of buildings and structures for various purposes made of carbon steel and low-alloy steel of classes C38 / 23 SBO / ^ 5 ”erected and operated in areas with a design temperature above minus ^ 0 ° and up to minus 65 ° C inclusive.

1.2. The manual applies to the following types of mounting connections on high-strength bolts:

frictional, in which shear forces are transmitted through friction that occurs along the contacting planes of the connected elements *

with load-bearing high-strength bolts in which shear forces are transmitted both through friction and due to the operation of the bolts for shearing and crushing, * bolt rivets used in the repair of riveted steel building structures, in which the decrease in bearing capacity is compensated by the friction force acting along the contacting planes of the joints elements when replacing defective rivets with high-strength bolts;

welded bolts used to strengthen mounted steel structures with frictional joints due to welding of parts with beads, in which shear forces are transmitted both through friction, and due to the work of the welds on the cut;

bolt glue, in which shear forces are transmitted by means of adhesion from adhesion and friction ^

flanged, in which high-strength bolts work only in tension with rigid flanges or in tension and bending with compliant flanges.

1.3 - Friction joints on high-strength bolts should be designed in accordance with SNiP II-B. 3 ”72" Steel structures. Norms of design "and normative documents supplementing it.

Other types of steel structure joints with high-strength bolts listed in clause 1.2 should be designed in accordance with special specifications.

1. * ♦. In the drawings of metal structures (Km) with joints on high-strength bolts, the following shall be indicated: type of joint;

nominal diameters and method of making holes;

standards for the manufacture and supply of high strength bolts, nuts and washers;

steel grade of bolts, nuts and washers; temporary tensile strength of steel bolts, * axial force of tension of bolts; method of tensioning bolts;

a method of processing contact surfaces;

the coefficient of friction used in the calculation; materials for the preparation of adhesives and coatings of contacting surfaces;

parts and areas not subject to priming; specification of bolts, nuts and washers; guidance documents on connection technology.

2. MATERIALS. PRODUCTS AND TERMS OF USE

2.1. To connect elements of steel building structures, high-strength bolts, nuts and washers made in accordance with the requirements of GOST 22353 - 77 ~ 22356 - 77 should be used.

Mechanical your

Mechanical

Nominal diameter of a thread, mm	temporary resistance (lowest) d b, MPa (kgf / mm 7)		brinell hardness, units HB, the largest

Applies AOX "Select

steel with narrowed limits co and AOKHFA "Select", from 0.35 to

bolts

Table 1

properties

relative narrowing of p,%, not less		elongation &,%, not less than	viscosity
			MJ / m 2, (KGS-m / cm ^
				40X "Select" 1
				38ХС "Select" 40ХФА "Select"
				40X "Select"
				40X "Select"
				40X "Select"
				40X "Select"

carbohydrate retention: 0.37 to 0.42 for Ma-O steel. - for steel grade 38XC "Select".

Table 2 Mechanical properties of nuts

up to 27 1100 241 341

(by)

	** 0X 750 (75) 229
	Tb 38HS 1350
	16 ZOZMF 1550		388 ZOKHZMF
	30HZMF1200 35HZAF0 20)
	ZOKHZMFYUOO

Table 3

Mechanical properties of washers

2.2. High-strength bolts are designed for two types of operation:

climatic modification U, placement category 1 in areas with a design temperature minus A0 ° C and above;

climatic modification of CL, placement category 1 in areas with a design temperature from minus AO C to minus 65 C.

2-3. The mechanical properties and materials of bolts, nuts and washers must meet the requirements of table. 1 “3“

2.A. The main dimensions of high-strength bolts, nuts and washers must meet the requirements of table. A.

2.12. As a material for the preservation of cleaned by sandblasting or shot blasting contact surfaces  connections on high strength bolts should be used

Table 5

eP-057 epoxy tread primer according to TU 6-10-11171 with hardener IT 3 according to TU 6-10-1091-71, with a solvent according to

hoists and sizes

Permissible deviation from the design linear dimensions, + mm

Size intervals, m

Shapes sent for installation

Continuation of the table.

Details and permissible deviation from the design linear linear dimensions, + mm

2. The distance between the centers of the holes: extreme adjacent

Shipping items after final manufacturing

3. Width and height

C. Length 2.5

5. The distance between the groups

holes 2.5

Notes: 1. Roulettes of the second accuracy class should be used for measurements. 2. For free edges in pos. 1, 2 deviation up to +5 mm is allowed.

Table 9

Deviations

Direction of parts 1. The gap between the gusset sheet and a steel linear length of 1 m 1.5 mm

Continuation of the table. 9

Deviations	Tolerance from the design geometric shape of the sending elements
2. The gap between the tightened
string shelf or walls
shipping element
ta (element length L)	0.001L but not more
3. Skewed and mushroom-shaped
shelves (D) ele-
cops of t-brand and two
t-section (width -
on the shelves, b):
at the joints and in places
in other places
in the upper belts under
crane beams
Helical
elements ^ length of ele
	0.001 L but not more
5. Wall bucking
ki of beams (wall height -
without vertical
stiffener
with vertical re-
sconces
6. The gap between the fre
zerovannoy over
edge and edge
steel ruler
1 m long

4. TECHNOLOGY FOR PERFORMING COMPOUNDS

* 4.1. Making connections on high-strength bolts and accepting them should be carried out under the direction of the person designated as responsible for the implementation of this type of connection by order of the organization performing these works.

* 4.2. To make connections on high-strength bolts, personnel who have received appropriate training and have a certificate of admission to this work are allowed. For the recommended training program and certification form, see app. 1 * 4.

* 4.3. The technological process of making connections on high-strength bolts includes the following operations:

processing of contacting surfaces of elements and parts;

preparation of high-strength bolts, nuts and washers;

assembly of connections;

high-strength bolt tension;

acceptance and sealing of joints.

HANDLING SURFACES SURFACING

*4. *4. The value of the coefficient of friction, and hence the bearing capacity of the joint, depends on the method of processing the contacting surfaces.

The following processing methods are most commonly used:

pneumatic - quartz sand or metallic sand;

fire - with multi-flame burners (\\ on acetylene);

steel hand or mechanical brushes. In addition, combined slabs have been tested, in which the linings and gaskets are processed pneumatically or by applying a stick coating, and the elements

hands - steel manual or mechanical brushes.

^ .5 “The assembly of joints and the tension of all high-strength bolts should be carried out in the shortest possible time, but no later than 3 days after processing the contacting surfaces.

In individual cases, taking into account climatic conditions and additional measures to protect the treated surfaces, the above-mentioned periods can be increased with the agreement of the TsNIIproektstalkonstruktsiya institute.

k.6. Cleaned surfaces should be protected from dirt, oil and paint, as well as from the formation of ice.

If dirt, oil, paint, ice forms and if the storage period is exceeded, re-treatment should be carried out. Reprocessing of surfaces is carried out by the method used in the initial processing.

Notes: 1. Re-processing requirements

boots do not apply to plaque of rust formed on contacting surfaces after cleaning, as well as to the case of atmospheric precipitation in the form of moisture or condensation of water vapor.

2. Repeated firing is possible instead of pneumatic.

PNEUMATIC TREATMENT

^ .7 * During pneumatic treatment, mill scale and rust must be completely removed until a homogeneous light gray metal surface is obtained.

M. For pneumatic treatment, well-washed and dried quartz sand should be used with a SiC ^ ne content lower and a grain size of up to 2.5 mm with the lowest possible clay fraction content.

Novosibirsk

Connections on high strength bolts. Features of work and calculation. 2

Types of columns in building structures. 6

The main elements of the steel frame of an industrial building. 8

Connections on high strength bolts.

Features of work and calculation.

High-strength bolts are made of alloy steel, they are placed in holes of a larger (3 mm) diameter than the bolt. The nuts are tightened with a calibration wrench, allowing you to control and adjust the tension of the bolts. The greater the tension of the bolt, the denser and more monolithic the connection. When a shear forces acts on such a connection, frictional forces arise between the elements to be joined, which prevent the elements from moving relative to each other. Thus, a high-strength bolt, working on axial tension, provides the transfer of shear forces by friction between the connected elements, which is why such a connection is often called friction. To increase the friction forces, the surfaces of the elements at the junction are cleaned of dirt, oil, rust and scale with metal brushes, a shot-blasting machine, fire cleaning or chemical pastes and are not painted.

Bolted connections on high-strength bolts with controlled tension can be both friction and friction-shear (part of the force is transmitted through the friction of the surfaces of the connected elements, and part through crushing, as with uncontrolled tension).

In order for the bolts to withstand large tightening forces, they are made of special steels and subjected to heat treatment. Each batch of bolts is supplied with certificates.

High-strength bolt joints offer the benefits of conventional bolted connections  and are not inferior in quality of work to riveted joints. Only those installers who have passed the appropriate training and have access to this work are allowed to make connections on high-strength bolts. Work is carried out under the supervision of a specially designated person.

Friction joint on high-strength bolts - this is tension with controlled tension of bolts. Friction forces arising in the connection on contacting surfaces from the tension of the bolts and perceiving shear forces are determined depending on the strength of the bolt rod and the nature of the processing of the contacting surfaces. Crucial in the operation of such a connection is the tension force of the bolt. It is believed that this force is equal to the calculated tensile strength of a high-strength bolt:

Where P is the axial tension force; - the estimated tensile strength of the material of high strength bolt,   , is the least tensile strength of the bolt material (see tab. 61 SNiP II-23-81 *); - the cross-sectional area of \u200b\u200bthe net bolt, determined according to the standard.

The estimated force that can be perceived by each plane of friction of the connected elements pulled together by one high-strength bolt (one bolt contact) is determined by the formula:

Where is the coefficient of the working conditions of the bolted connection, µ-coefficient. friction, taken according to the table. 36 * SNiP II-23-81 *; -coef. reliability, determined by the same table.

The norms provide for the account of the uneven operation of the bolts in the connection (for example, uneven tension). In accordance with this coefficient. they propose to consider equal to 0.8 at 0.9 at and 0.1 at, where n is the number of bolts in the connection.

In friction joints, the tension of the bolts is controlled either by the angle of rotation of the nut a, or by the moment of tightening the nut M (the moment of force applied to the handle of the wrench relative to the center of the hole). Strength analysis of the connected elements themselves by high-strength bolts is carried out taking into account the fact that the shear forces are already transmitted (in whole or in part) by the friction forces of the connected surfaces that are outside the place of weakening of the section by the holes.

The workflow includes the following operations: processing of the contacting surfaces of elements and parts; preparation of bolts, nuts and washers; assembly of connections; bolt tension; acceptance and sealing of joints. The cleaned surfaces protect from dirt, splashes of oil and paint, the formation of ice. Otherwise, cleaning has to be performed anew. Bolts, washers and nuts are re-mothballed and cleaned of dirt and rust. On discarded bolts, the threads are driven off, grease is applied. Reconservation - cleaning from factory grease and applying a protective grease - is carried out by keeping the product in boiling water for 10 minutes and then washing them in a mixture of unleaded gasoline (85%) and mineral oil such as autol. From the heated hardware, gasoline evaporates quickly, oil in the form of a thin film remains on the surface. Each bolt is installed in connection with two high-strength washers (one is placed under the head of the bolt, the other under the nut). It is forbidden to put more than one washer on each side of the bag.

At the time of installation of the bolts, the nuts must turn freely (by hand) in the thread, otherwise the nut or bolt is replaced, and the rejected bolts and nuts are sent for re-training. Places and installation stages of plugs and bolts, as well as the sequence of bolt tension, are indicated in the design of the work.

The joints are assembled and tightened, observing the general requirements for the assembly of bolted joints. Then the bolts are wrapped in the force provided by the project. Moreover, the connections are collected immediately on high-strength bolts and plugs - it is forbidden to use other bolts as assembly.

Finally, high-strength bolts are tightened to the design force after checking the geometric dimensions of the assembled structures. The specified bolt tension is provided by one of the following methods of regulating forces: by the angle of rotation of the nut; axial bolt tension; at the time of twisting with an indicator type key; by the number of impact wrenches. At the same time, the work is carried out in accordance with the "Guidelines and standards for the technology of setting high-strength bolts in the mounting joints of metal structures".

The sequence of bolt tension is from the middle of the joint or from the most rigid part towards the free edges. The bolt head may only be held at the initial stage of tension. The turning bolts must be replaced. Nuts or bolt heads tightened to the design effort are marked with paint or chalk.

The quality of joints on high-strength bolts is checked by operational control and upon acceptance of work (quality of preparation of contact surfaces, accuracy of bolt tension and tightness of a tightened bag). The density of the package tie is checked with a 0.3 mm thick probe - it should not go deeper between the assembled parts by more than 20 mm.

The axial forces of the bolts are controlled in accordance with the method of tension. Regardless of the method of tensioning, the controller first of all inspects all bolts supplied from the outside and makes sure that all bolts are marked, washers are placed under all nuts and heads; the parts of the bolts protruding beyond the nut have at least one thread turn over the nut and two under the nut; on the assembled unit there is a stamp of the team that performed these works.

The tension of the bolts is controlled selectively: with the number of bolts in the joint up to 5 - all bolts, with 6 ... 20 - at least 5 bolts and with a larger number - at least 25% of the bolts in the joint. If the quality of at least one bolt is unsatisfactory, double the number of bolts is controlled. If, in this case, a defective bolt is detected, all the bolts of this connection are checked and their tension is adjusted to the required one.

The control results are logged. At each connection, the stencil of the control worker should be applied with paint. After accepting the connection by the controller, all external surfaces of the joints are primed.