Snip installation of prefabricated reinforced concrete structures. Installation of prefabricated reinforced concrete structures. Types and methods of installation of steel and reinforced concrete structures

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Introduction

1. Technological part

2. Mechanical part

2.3 Calculation of shell wall thickness

2.4 Bottom calculation

2.5 Calculation and selection flange connection

2.6 Calculation of hole reinforcement

3. Installation part

3.1 Transportation of equipment, device to the installation site

3.3 Selection of supports

3.4 Testing

4. Labor protection

4.2 Fire safety

4.3 Environmental protection

5. Conclusions

List of sources used

Introduction

equipment structural installation material

In conditions of constant growth in the volume of industrial, civil and housing construction carried out in our country, it plays an important role industrial a method of building from prefabricated prefabricated structures. Industrial construction allows you to turn construction sites into assembly, in which the mechanized assembly of buildings and structures is carried out from elements manufactured in specialized factories. It is the basis of technical progress in this industry National economy, reduces labor intensity, shortens the duration of construction, improves its quality and reduces cost, and reduces the time it takes to put objects into operation. Specific gravity installation work in construction is increasing every year. Along with the continued use of prefabricated reinforced concrete structures in the coming years, further growth in the use of metal structures. The development of installation work as a leading construction process is based on the spread of comprehensive mechanization and automation of work. Improvement plays a big role in this. assembly machines, the fleet of which is constantly growing, an increase in their carrying capacity makes it possible to increase the mass of mounted units.

For the development of installation processes, they play a significant role efficient materials and designs. Such materials and products include: lightweight concrete, asbestos and reinforced cement products, synthetic materials, sealants, foam plastic, aluminum alloys, etc. The development of installation work is facilitated by the use of reinforced concrete and metal prestressed structures, structures made of tubular elements, cable-stayed, structural , membrane, prefabricated reinforced concrete shells, as well as lightweight structures of coverings made of profiled stamped flooring and sheets of aluminum alloys, spatial blocks. The technology and organization of installation work are being improved, installation methods such as non-alignment, forced installation, installation of large construction technological blocks and fully completed blocks, conveyor method, allowing to reduce the labor intensity of work. Mastered and improved installation With Vehicle. Much attention is given preparatory work and integrated assembly, configuration and maximum readiness of mounted structures and building elements, leading to a reduction in the labor intensity of auxiliary processes, a reduction in the amount of work at height and unproductive movement of installers.

However, the installation process still involves a large number of manual operations, mainly related to alignment and sealing of joints. Mechanization and automation of such work are urgent improvement tasks installation process. Volume reduction manual labor during installation building structures should be based on a sharp increase in the level of installation manufacturability and carried out by improving installation machines, comprehensive mechanization, widespread automation and robotization construction production, increasing the level of factory readiness of mounted structures.

1. Technological part

1.1 Literature review existing structures equipment

Column apparatuses are cylindrical vertical vessels of constant or variable cross-section, equipped with internal heat and mass transfer devices (plates, nozzles), as well as auxiliary units that ensure technological process(rectification, absorption, extractive rectification, extraction, direct heat exchange between steam and liquid.

Rice. 1 Column apparatus diagram

Classification of column devices

Devices column type can be classified depending on the technological purpose, operating pressure and type of contact (mass transfer) devices.

INdependenciesfromappointments each mass transfer apparatus bears the name of a specific, targeted mass transfer process: distillation column, absorber, adsorber, extractor, etc.

Rectification Column - this is the apparatus in which the rectification process takes place, i.e. mass transfer between the liquid and vapor phases for clear separation of components (a mixture of two mutually soluble liquids to obtain target products of the required concentration). This separation is ensured as a result of the rectification process, which is understood as two-way mass transfer between two phases of solutions, one of which is vapor, the other liquid. The diffusion process of separating liquids by rectification is possible provided that the boiling points of the liquids are different. To achieve diffusion, vapors and liquids must be in contact with each other as best as possible, moving towards each other in the distillation column: the liquid under own weight from top to bottom, pairs - from bottom to top.

From the properties of an equilibrium system it is known that when nonequilibrium vapor and liquid phases come into contact, the system tends to a state of equilibrium as a result of mass transfer and heat exchange between these phases. Therefore, for rectification to occur, it is necessary that the contacted liquid and vapor at the same pressure are not in equilibrium. In other words, the temperature of the liquid must be lower than the temperature of the vapor.

Distillation columns are widely used in various industries, in particular, in oil and gas refining for the separation of oil and fuel oil in primary distillation units, gasoline in secondary distillation units, hydrocarbon gases at gas fractionation plants (GFU), reaction products at plants

Rice. 2 Distillation column

Absorber - this is a device for selective absorption by liquid (absorbent) of target components original gas mixture.

The absorption process occurs when partial pressure or the concentration of the extracted component in the gas mixture is greater than in the absorbent. The greater this difference, the more intense the transition of the component from the gas mixture to the liquid (absorbent). When the partial pressure or concentration of a component in a liquid is greater than in the gas mixture, desorption occurs - the release of dissolved gas from solution.

Absorbers and desorbers work in pairs. In some cases, absorption and desorption are carried out sequentially in the same apparatus. Absorbers and desorbers are usually not structurally different from each other.

Rice. 3 Absorber with a regular nozzle Fig. 4 Absorber with combined contact devices

Adsorber - an apparatus in which the adsorption process takes place, i.e. mass transfer between solid and liquid phases to extract the required components from the mixture.

The adsorption process consists of selective absorption of a substance by the surface of an adsorbent - porous solid. This absorption is explained by the presence of mutual attractive forces between the molecules of the adsorbent and the molecules of the adsorbed substance. Adsorbents are used in the form of grains up to 10 mm in size and in a dusty state. Molecular sieves are also used - synthetic zeolites with pores of the same size.

Adsorption is usually used to separate “lean” mixtures (containing small amounts of absorbed substances) and mixtures consisting of difficult-to-separate components. At oil refineries, oils and paraffin are purified by adsorption, gasoline is extracted from hydrocarbon gases, gases and air are dried, etc.

The substance absorbed by the adsorbent is released from it by desorption - a process reverse to adsorption. As a result of desorption and subsequent processing of the adsorbent, it is regenerated and can be used again.

Desorption and regeneration of the adsorbent is carried out with water vapor and various liquids, from which the target substances are then extracted. Non-target components can be burned out if the regenerated adsorbent does not lose its inherent properties.

In most cases, adsorbers and desorbers are column devices. The most complex devices continuous action- adsorbers with a moving granular adsorbent and adsorbers with a fluidized bed of adsorbent.

Extractor- the apparatus in which the extraction process is carried out, i.e. mass transfer between two liquid phases to remove undesirable components from the mixture, etc.

Liquid extraction in oil refining is used to purify oils, as well as in production diesel fuel and kerosene. The extraction process involves separating a mixture of components by treating the solid or liquid phase with a liquid selective solvent. Furfural, phenol, liquid sulfur dioxide, diethylene glycol, liquid propane, etc. are used as selective solvents.

The designs of extractors must ensure thorough contact of mass-exchanging phases and their subsequent separation. Most extractors are columns with trays or packing. In columns, extraction is carried out by contacting raffinate and extract solutions in countercurrent.

INdependenciesfromappliedpressure Columns are divided into atmospheric, vacuum and columns operating under excess pressure.

TO atmospheric columns usually refer to columns in the upper part of which operating pressure slightly exceeds atmospheric pressure and is determined by the resistance of communications and equipment located in the flow of rectified vapor after the column. The pressure at the bottom of the column depends mainly on its resistance internal devices and can significantly exceed atmospheric pressure (for example, a column for separating a mixture of ethylbenzene and xylenes). In columns working under redundant pressure , the value of the latter can significantly exceed atmospheric pressure - the pressure can reach 100 or more MPa.

Pressure is one of important factors operation of columns. For example, for rectification processes the main prerequisite for its selection is temperature regime process. Increased pressure allows fractionation to be carried out at high temperatures, which is necessary in the case of separating mixtures consisting of components with low boiling points (distillation of low molecular weight hydrocarbons).

In a distillation column, the pressure varies along the height of the apparatus depending on the hydraulic resistance of the plates and baffles.

To separate components from high temperature boiling point, rectification should be carried out at low temperatures to avoid the decomposition of high molecular weight hydrocarbons - at their boiling point. For this purpose, rectification is carried out in vacuum columns, where boiling temperatures are artificially reduced depending on the magnitude of the vacuum. Vacuum columns are especially common, used in fuel oil distillation plants to obtain oil distillates.

IN vacuum In the columns, the pressure is below atmospheric (a vacuum is created), which makes it possible to reduce the operating temperature of the process and avoid product decomposition (separation of fuel oil, production of styrene, synthetic fatty acids, etc.). The residual pressure in the column is determined physical and chemical properties shared products and mainly permissible maximum temperature heating them without noticeable decomposition.

Mass transfer contact devices

For to ensure effective contact of phases, as mentioned earlier, mass transfer columns are equipped with mass transfer devices.

Currently, a large number of different mass transfer devices are known, while the development of new progressive ones continues. This is explained by the fact that mass transfer devices are subject to a large number of requirements, many of which contradict each other. Therefore, it is impossible to develop a universal design of mass transfer devices.

The areas of application of contact devices are determined by the properties of the mixtures being separated, the operating pressure in the apparatus, steam (gas) and liquid loads, etc.

The following basic requirements are imposed on the designs of mass transfer devices: low cost, ease of maintenance, high performance, maximum developed contact surface between phases and efficiency of transfer of mass of matter from one phase to another, stability of the regime in a wide range of loads, maximum throughput in vapor (gas) and liquid phase, minimum hydraulic resistance, structural strength and durability, etc.

Depending on the method of organizing phase contact, mass transfer devices are usually divided into disk, packed and rotary.

About 60% of manufactured column devices for absorption and rectification are plate columns, the rest are packed. Latest at proper organization Fluid dynamics processes are often more economical than plate processes.

Column devices are divided into plate, packed and film.

Rotary and film ones are little used in industry due to the complexity of manufacturing and high cost, so they are not considered here.

Disc mass transfer devices

IN In the oil refining industry, disk-shaped column devices are most widely used. In a plate column, the mass transfer process is carried out by repeated stepwise contact of two phases. For this purpose, it is equipped with special devices - plates, on which mass transfer mainly occurs, except for minor mass transfer in the free volume of the column. The plates are mounted horizontally inside the column.

IN distillation columns plates are used various designs, significantly different in their performance characteristics and technical and economic data.

When evaluating plate designs, the following indicators are usually taken into account:

1. performance;

2. hydraulic resistance;

3. efficiency under different workloads;

4. range of workloads in conditions of fairly high efficiency;

5. resistance of one theoretical plate under different operating loads;

6. the ability to work in environments prone to the formation of encrustations, polymerization, etc.;

7. simplicity of design, manifested in the complexity of manufacturing, installation, and repairs;

8. metal consumption.

Plates universal designs, like other mass transfer devices, does not exist. In most cases, for assessment it is enough to have data on indicators A, V And G; if they differ relatively little, then analyze the indicators e, and And h. Indicators b And d have great importance for vacuum and multi-plate columns, where the resistance of the apparatus plays a decisive role. Therefore, in a number of cases, for vacuum columns it may be advisable to use trays with relatively low efficiency and low hydraulic resistance.

Basics of classification of plate mass transfer devices

IN Currently, hundreds of different plate designs are known in industrial practice, many of which have only purely cognitive value. Other designs, although different separate elements, in the practical field have equivalent basic indicators. Until now, there is no sufficiently coherent classification of disk devices, although attempts in this direction have been made several times. Therefore, only general principles, which will allow you to navigate through the variety of available plate designs and make their preliminary assessment

1.2 Description and justification of the chosen design

Rice. 5 Distillation column

Rectification has been known since early XIX centuries as one of the most important technological processes mainly in the alcohol and oil industries. Currently, rectification is used all over the world in the most various areas chemical technology, where the separation of components into pure form has quite important. Rectification is a process of repeated evaporation and condensation, during which the original mixture is divided into 2 or more components, and the vapor phase is saturated with a highly volatile (low-boiling) component, and the liquid part of the mixture is saturated with a highly volatile (high-boiling) component.

Distillation column is a cylindrical vertical vessel of constant or variable cross-section, equipped with internal heat and mass transfer devices and auxiliary units, designed for separation liquid mixtures into fractions, each of which contains substances with similar boiling points. The classic column is a vertical cylinder, inside of which contact devices are located - plates or nozzles. Accordingly, a distinction is made between rectification columns: plate and packed.

The principle of operation of the column is to supply the initial mixture, heated to the feed temperature in the vapor, vapor-liquid or liquid phase, entering the column as feed. The zone into which power is supplied is called evaporation, since the process of evaporation occurs there - a single separation of steam from liquid. Couples rise into top part columns are cooled, condensed in a refrigerator-condenser and fed back to the upper plate of the column as reflux. Thus, in the upper part of the column (strengthening) vapors move in countercurrent (from bottom to top) and liquid flows down (from top to bottom). Flowing down the plates, the liquid becomes enriched with high-boiling components, and the vapors, the higher they rise up the columns, the more they become enriched with low-boiling components. Thus, the product removed from the top of the column is enriched with a low-boiling component. The product removed from the top of the column is called distillate. The portion of the distillate condensed in the condenser and returned back to the column is called reflux or reflux. The ratio of the amount of reflux returned to the column and the amount of distillate withdrawn is called the reflux ratio. To create an upward flow of vapors in the bottom (lower, stripping) part of the distillation column, part of the bottom liquid is sent to the heat exchanger, and the resulting vapor is fed back under the bottom plate of the column.

Thus, 2 streams are created in the cube of the column: 1 stream - liquid flowing down from the top (from the feeding + irrigation zone) 2 stream - vapor rising from the bottom of the column.

The bottom liquid, flowing from top to bottom along the plates, is enriched with high-boiling components, and the vapors are enriched with low-boiling components.

If the distilled product consists of two components, the final products are the distillate leaving the top of the column and the bottoms. The situation becomes more complicated if it is necessary to separate a mixture consisting of large quantity factions.

Classification of distillation columns

Used in oil and gas processing distillation columns are divided:

1) according to purpose:

For atmospheric and vacuum distillation of oil and fuel oil;

Secondary distillation of gasoline;

Stabilization of oil, gas condensates, unstable gasolines;

Fractionation of refinery, petroleum and natural gases;

Distillation of solvents in oil purification processes;

Separation of products of thermodestructive and catalytic processes of processing of petroleum raw materials and gases

2) according to the method of interstage fluid transfer:

With transfer devices (with one, two or more);

Without failure-type flow devices

3) according to the method of organizing contact between the vapor-gas and liquid phases:

Disc-shaped

Attachments

Rotary

According to the type of contact devices used, the most widely used are disc and packed distillation columns.

Hundreds of different designs of contact devices are used in distillation columns, differing significantly in their characteristics and technical and economic indicators. At the same time, they are in operation along with the most modern designs contact devices of such types (for example, grooved plates), which, although they provide the target products, cannot be recommended for modern and future production.

When choosing the type of contact devices, the following basic indicators are usually used:

a) productivity;

b) hydraulic resistance;

c) coefficient useful action;

d) range of workloads;

e) the ability to work in environments prone to the formation of resinous or other deposits;

e) material intensity

g) simplicity of design, ease of manufacture, installation and repair

Industrial distillation columns can reach 80 meters in height and more than 6.0 meters in diameter. In distillation columns, plates, which give the name to the chemical term, and packings are used as contact devices. The nozzle filling the column can be metal, ceramic, glass and other elements of various shapes.

Based on their operating principle, rectification plants are divided into periodic and continuous. In continuous installations, the crude mixture to be separated enters the column and the separation products are removed from it continuously. In installations periodic action The mixture to be separated is loaded into the cube simultaneously and rectification is carried out until the products of the specified final composition are obtained.

In rectification and absorption columns, trays of various designs are used (cap, valve, jet, failure, etc.), which differ significantly in their performance characteristics and technical and economic data. When choosing the design of a contact device, both their hydrodynamic and mass transfer characteristics and the economic performance of the column when using one or another type of contact device are taken into account.

Sieve plates. A column with sieve plates is a vertical cylindrical body with horizontal plates, in which a significant number of holes with a diameter of 1-5 mm are drilled evenly over the entire surface. Gas passes through the holes of the plate and is distributed in the liquid in the form of small streams and bubbles. Mesh plates are distinguished by their simple design, ease of installation, inspection and repair. The hydraulic resistance of these plates is low. Mesh trays operate stably in a fairly wide range of gas velocities, and at certain gas and liquid loads these trays have high efficiency. However, sieve trays are sensitive to contaminants and sediments that clog the tray openings.

Cap plates. Less sensitive to contamination than sieve and have a higher interval stable operation columns with cap plates. Gas enters the plate through pipes, then is broken up by the slots of the cap into big number separate jets. Next, the gas passes through a layer of liquid flowing over the plate from one drain device to another. When moving through the layer, a significant part of the small jets breaks up and the gas is distributed in the liquid in the form of bubbles. The intensity of foam and splash formation on cap plates depends on the speed of gas movement and the depth of immersion of the cap in the liquid. Cap plates are made with radial or diametric overflow of liquid. Cap plates operate stably under significant changes in gas and liquid loads. Their disadvantages include the complexity of the device and high cost, low ultimate loads gas, relatively high hydraulic resistance, difficulty in cleaning.

Valve plates. The principle of operation of valve discs is that a freely lying round valve, which is freely lying above the hole in the disc, with a change in gas flow, with its weight, automatically regulates the size of the gap area between the valve and the plane of the disc for the passage of gas and thereby maintains constant speed gas as it flows into the bubble layer.

1.3 Selection of lifting equipment

Rice. 6 Calculation scheme

Determining the required lifting capacity of the crane

Gtr - cargo mass, t

Lcm - distance from the base to the center of mass, m

Lc - distance from the base to the slinging point, m

Lc = H0 - when slinging over the top of the equipment, m

N k - number of cranes involved in lifting equipment, pcs.

Determining the lifting height of the hook for lifting equipment

where h f - foundation height, m

h 0 - height of equipment to the slinging point, m

h c - length of the sling connecting the load to the crane hook, m

We choose an assembly crane of the SKG 160 brand with a boom length of 30m, a lifting capacity of 82t and a hook reach of 50m.

Rice. 7 Load-height characteristics of the SKG-160 crane

2.2 Calculation of the extension system

Rice. 8 Calculation diagram of the extension

Determining the pulling force

where G 0 is the mass of the equipment, t

Force acting on the hook of the movable block of the pulley block

Force on the stationary block

We select movable and fixed blocks according to higher value efforts

Load capacity - 1000 kN

Number of rollers in a block - 5 pcs. (total number of rollers 10 pcs.)

Roller diameter 750 mm

Block weight - 1760 kg (total weight 3520 kg)

The length of the pulley when pulled together is 3500 mm

Force in the running thread of the chain hoist

where m n is the total number of working rollers excluding outlet rollers, pcs.

Efficiency of the pulley block taking into account the branch blocks

We calculate the breaking force in the rope

where S is the force in the rope, kN

k z - safety factor of the rope

Choosing a rope for a chain hoist of the LK-RO brand

6x36(1+7+7/7+14)+1o.s.

Rope diameter - 23.5 mm

Breaking force - 338 kN

Weight 1000m - 2130 kg

Determining the length of the rope for the pulley system

where m is the total number of rollers

H - length of the pulley when stretched, m

h 1 - reduction value of the pulley, m

h 2 - length of the pulley when pulled together, m

D r - roller diameter, m

l 1 - length of the running thread of the pulley block, m

l 2 - length of rope reserve, m

Total weight of the pulley

where G b is the mass of both pulley blocks, kg

G to - mass of rope for pulley hoist, kg

G 1000m - mass of 1000 m of rope, kg

The force acting on the rope securing the stationary block of the pulley operating at an angle (when the rope branch runs down from the moving block)

Rope breaking force to secure a fixed block

where m is the number of branches in the sling, pcs

Selecting a rope to secure a fixed block of the LK-RO brand

6x36(1+7+7/7+14)+1o.s.

Marking group - 1960 MPa

Rope diameter - 25.5 mm

Breaking force - 383 kN

Weight of 1000m rope - 2495 kg

We select a winch based on force S n

Winch type LMN-12

Traction force - 125 kN

Rope capacity - 800 m

Drum diameter - 750 mm

Weight of winch with rope - 5643 kg

Determine the required mass of the anchor to secure the winch

Rice. 9 Design diagram of the anchor

N 1 - horizontal load component

N 2 - vertical component of the load

b - angle of inclination of the anchor rod to the horizon

k y - anchor shear stability coefficient

G l - winch weight, kg

Determine the required number of concrete blocks for the anchor

where q b - mass of one block, pcs

Table 1

Concrete blocks

Anchor mass

where m is the number of blocks, pcs

Checking the anchor for capsizing

where b is the holding moment arm

a - arm of the overturning moment from the traction force

1.4 Description of the process plant

Rice. 10 Schematic diagram atmospheric distillation unit of the ELOU-AVT-6 installation: 1-topping column; 2-atmospheric furnace; I-oil with ELOU; II-light gasoline; III-gas

The atmospheric distillation unit of the high-performance, most common in our country, ELOU-AVT-6 unit operates according to a double evaporation and double rectification scheme.

Dehydrated and desalted oil in the ELOU is additionally heated in heat exchangers and supplied for separation to the partial topping column 1. The hydrocarbon gas and light gasoline leaving the top of this column are condensed and cooled in air and water cooling units and enter the reflux tank. Part of the condensate is returned to the top of column 1 as acute reflux. Stripped oil from the bottom of column 1 is fed into a tubular furnace, where it is heated to the required temperature and enters an atmospheric furnace. Part of the stripped oil from the furnace returns to the bottom of the column as a hot stream.

2. Mechanical part

2.1 Selection of construction materials

For the device body, we select, according to the recommendations, sheet steel grade 16 GS in accordance with GOST 10885-5, for which the technical requirements are in accordance with GOST 10885-5; operating conditions: tR = 240°С; p=0.5 MPa. Types of tests and requirements according to GOST 10885-5 (tests are carried out at the metal supplier plant at the customer’s request). When choosing the material, the following was taken into account: the corrosive properties of the environment. At given operating parameters, the corrosion rate is less than 0.1 mm/year. technological properties of the material used: weldability, ductility and others. influence of construction material on the quality of the initial mixture and separation products. technical and economic considerations: stainless steel is widely used in chemical engineering and other industries. Welding is automatic. Electrode type according to GOST 10052-5 -E-04Х20Н9. The supports are cylindrical. The material of the support parts must be selected based on the operating conditions and in accordance with technical requirements OST 26-91-4.

2.2 Determination of design parameters

Operating and design temperature

Design temperature T R is the temperature to determine physical and mechanical characteristics structural material and permissible stresses. It is determined based on thermal calculation or test results. If during operation the temperature of an apparatus element may rise to the temperature of the medium in contact with it, the design temperature is taken to be equal to the operating temperature, but not less than 20 °C. The designed apparatus is equipped with insulation that prevents the external environment from cooling or heating the apparatus elements.

The operating temperature of the device is T=240 °C.

Design temperature Т Р =240°С.

Working, design and conditional pressure

Working pressure P - the maximum excess pressure of the medium in the apparatus during the normal course of the technological process, without taking into account the permissible short-term increase in pressure during operation safety device P=0.5MPa.

Design pressure P R - the maximum permissible operating pressure at which the strength and stability of the apparatus elements are calculated at their maximum temperature. Usually, design pressure may be equal to the operating pressure.

The design pressure can be higher than the working pressure in the following cases: if, during the operation of the safety devices, the pressure in the device can increase by more than 10% of the working pressure, then the design pressure should be equal to 90% of the pressure in the device when the safety device is fully opened; if an element is subject to hydrostatic pressure from the liquid column in the apparatus, the value of which is more than 5% of the calculated one, then the calculated pressure for this element accordingly increases by the value of the hydrostatic pressure.

2.3 Determine the wall thickness of the cylindrical shell of the apparatus

operating under internal excess pressure and determine the value of the test pressure during hydrotesting, the permissible internal pressure under operating conditions and under hydrotesting conditions.

Initial data for calculation:

D- inner diameter shells, mm;

H is the height of the shell, mm;

P slave - working pressure, MPa;

T slave - temperature of the medium in the tank, °C;

P - corrosion rate, mm/year;

Device material-16GS

Environment - non-toxic, non-corrosive

1. Determine the estimated temperature of the apparatus wall:

At T>20ºC, T calc =T slave =240ºC (23)

2. We determine the permissible stress for the material of the apparatus under operating conditions and under hydrotest conditions:

a) in working conditions

[?]=?·? * , (24)

Where? * - determined from the table.

The correction factor for cast devices is 0.7-0.8; for welded devices it is 1;

b) under hydrotest conditions

[?] and =? t 20 /1.1, (25)

Where? t 20 - determined from the table.

3. We determine the calculated value of internal excess pressure under operating conditions:

P calculated = P slave + P g (26)

where P g =p g H-hydrostatic

where p is the density of the medium, kg/m 3 ;

g-gravitational acceleration, m/s 2;

H is the height of the liquid medium column in the apparatus, m.

If P g is less than 5% of

P slave, then P calculated = P slave

R g =1000·9.81·7.26=71220.6Pa=0.712 MPa

Since 0.712 MPa>0.0025 MPa, then P calculated =0.5+0.712=1.212 MPa

4. Determine the test pressure during hydrotesting:

for welding machines

P pr =max(1.25·P calculated; P calculated +0.3); (27)

where [?] 20 =?·? *

Where? * - determined according to the table for the material of the apparatus at 20 °C

1.25·Р calculated =1.25·1.212·=1.91 MPa

P race +0.3=1.212+0.3=1.512 MPa

P pr =max(1.91;1.512)=1.91 MPa

5. Determine the design and design wall thickness of the apparatus:

S race =max (28)

S race =max(2.09;2.1.59)=2.09 mm

c=c 1 +c 2 +c 3

c=2+0.1+0.3=2.4 mm

S=2.09+2.4=4.49 mm

We accept S=5mm

6. Determine the permissible internal pressure:

a) in working order

0.75>1.1 - the condition is met

[P] and >P pr

1.5>1.91 - not fulfilled

We increase the wall thickness to meet the strength condition

We accept S=7 mm

1.3>0.5 - condition is met

2.7>1.91 - the condition is met

7. We check the condition for the applicability of the formula:

We determine the wall thickness of the elliptical bottom of the apparatus operating under internal excess pressure and check the strength conditions.

1. Determine the design temperature of the apparatus wall:

at Т>20єС, Т р =Т=240єС (31)

2. We determine the permissible stress for the material of the device under operating conditions:

3. Determine the estimated wall thickness using the formula:

4. Determine the specific wall thickness

c=c 1 +c 2 +c No.

c=2+0.03+0.1=2.13

S=2+2.13=4.13mm

5. We determine the permissible internal excess pressure using the formula:

We check the applicability of the formula by the following condition:

6.Check the strength condition:

[P]> P v.r (35)

Selecting a flange connection for given operating parameters, selecting fasteners and determining the calculated bolt load on the flange.

1.Selection of flange connection

The type of flange connection is selected depending on the operating pressure and nominal diameter of the fitting

Purpose of flanges - For pipes and pipe fittings

Flange type - Steel flat welded with shoulder and cavity

Standard GOST 12828-67

The main geometric dimensions of flanges for pipes and pipe fittings are D y = 200 mm; D f =315 mm; D B =280 mm; D 1 =258 mm; D 2 =250 mm; D 4 =222 mm; D 6 =225 mm; h=19 mm; h 1 =18 mm; h 2 =18 mm;d=18 mm;z=8

The material of flanges and fasteners is the same as the body of the 16GS device

The type of gasket is selected depending on the shape of the mating surface of the selected flange connection

The gasket design is flat, non-metallic.

The gasket material is selected depending on the operating pressure, temperature and properties of the paronite medium

2. Calculation of bolt load of flange connection:

2.1 Determine the load on the bolts of the flange connection under medium pressure:

Q b 1 =·(d c +(2b/3)) 3 ·Р slave +р·D c ·b 0 ·m· Р slave, (36)

where d in is the internal diameter of the gasket, mm;

b=(D- d in)/2-gasket width, mm;

D c = d in + b is the average diameter of the gasket, mm;

b 0 - design width of the gasket, mm; Determined depending on the gasket design; for flat laying b 0 = b at b<0,012 м, при b>0.012 m b 0 =1.1v b; for oval-section gasket b 0 = b/4;

m-coefficient of specific pressure on the gasket.

b= mm=0.018 m

D c =222+18=240 mm=0.240 m

Q b 1 = 3 0.5+3.14 0.240 0.018 2.5 0.5=0.017 MPa

We determine the load on the bolts of the flange connection, which is not under pressure from the medium, ensuring compression of the gasket for reliable tightness:

Q b 2 =р · D c · · b 0 ·q pr, (37)

q pr - pressure on the surface of the gasket, MPa.

Q b 2 =3.14·0.240·0.005·20=0.075 MPa

Select the maximum value:

Q b =max( Q b 1; Q b 2) (38)

Q b =max(0.087;0.075)=0.087 MPa

Determine the load per bolt:

where n b - number of bolts

Determine the internal diameter of the thread:

where [?] b is the permissible stress for the bolt material at operating temperature, MPa

We determine the specified value of the load on one bolt:

Determine the minimum load on the bolts:

Q min =n q b 1 (42)

Q min =8·0.367=2.936 MPa

We calculate the flange parameters (disc thickness, welds) based on the design load:

Q p ==1.51 MPa

Calculation of a hole that does not require reinforcement, checking the strengthening of the cutout by thickening the wall of the cylindrical shell and the fitting pipe, determining the geometric dimensions of the reinforcing ring.

1. Determine the estimated diameter of the hole in the shell wall:

d p ​​=d+2c 5 (44)

d p ​​=200+2·2=204 mm=0.204 m

2. Determine the largest diameter of a single hole that does not require reinforcement in the presence of excess shell wall thickness:

where S p is the calculated thickness of the shell wall, mm.

D p is the calculated internal diameter of the element being strengthened. For a hole located on the shell and a standard elliptical bottom, in which H = 0.25 D, D p = D

The calculated diameter of a single hole satisfies the condition d p< d 0

0,204<0,2101-условие выполняется

3. Installation part

3.1 Transportation of the distillation column and apparatus to the installation site

Transportation is the process of moving cargo/object to its destination using one or another means of transport.

Oversized cargo is a cargo whose weight and dimensions exceed the dimensions allowed for transportation and the norms established by traffic rules. In other words, an oversize load is a load that cannot fit into a standard vehicle.

In our case, the cargo is a distillation column. Its parameters:

The column will be transported using vehicles.

The main documents regulating the transportation of oversized cargo by road in the Russian Federation:

1. Traffic rules

2. Rules for transporting goods by road

3. Rules for ensuring the safety of transportation of passengers and goods by road and urban ground electric transport.

According to the rules of the road (traffic rules) and the rules for transporting goods by road, transportation of oversized cargo must be carried out by a vehicle with dimensions not exceeding 2.55 m in width, 20 m in length (including trailer) and 4 m in height from the roadway with accounting for cargo.

The parameters of a loaded road train exceed the permissible limits, therefore special permission and a special pass are required for the passage of such a road train.

Transportation of oversized cargo is a complex and in some cases dangerous process, therefore:

· the load must be placed in such a way as not to impair or limit the driver’s visibility

· the load must not negatively affect the stability of the vehicle used, that is, it must be secured in accordance with all safety rules and must not provoke the vehicle to tip over during movement

· the load should not make it difficult to drive the vehicle

· the load must not interfere with the perception of signals given to the driver by road users, and must not block reflectors, identification signs, lighting devices and other devices

· the cargo must not produce noise or other sound interference, must not raise dust during transportation, or harm the road surface and the environment

· while driving, the driver must monitor the placement, securing and condition of the cargo being transported.

3.2 Description of installation methods. Installation of equipment

Lifting the device by rotating around the hinge is performed in the following sequence:

1) make a test lift of the top of the apparatus from the supports by 200-300 mm, holding for 15 minutes and checking the condition of the equipment and lifting equipment;

2) working with lifting equipment, in accordance with the lifting cyclogram, turn the apparatus at an angle that does not reach the unstable equilibrium position by 5-10 °;

3) turn on the brake guy, creating a load in it equal to 20-30% of the calculated one

4) using lifting means, move the apparatus through an unstable equilibrium position, transferring the load to the brake guy;

5) releasing the brake guy (system) and loosening the pulleys of the lifting equipment, lower the device to the design position.

1.2 Rotation around a hinge with pulling is a variation of the method of rotation around a hinge and is adopted in the case when lifting equipment does not have sufficient lifting characteristics to bring the device into the design position. In this case, it is rational to use the method of turning around the hinge by pulling at an angle of elevation of the apparatus of at least 70°

1.3 When lifting the device using the turning and pulling method, the work is performed in the following sequence:

1) according to clause 1.1, subclause 1;

2) raise the apparatus to the maximum angle determined by the lifting capacity, using the instructions in paragraph 1.1, subparagraph 2;

3) put the pulling system into operation and transfer the load from the lifting device to it;

4) allowing the braking pull, turn the device using the pulling system to an angle that does not reach the unstable equilibrium position by 5-10°;

5) according to clause 1.1, subclause 3;

6) using the pulling system, move the device through an unstable equilibrium position, transferring the load to the braking system;

7) according to clause 1.1, subclause 5;

3.3 Selection of supports

3.4 Testing

For large-sized devices of significant height installed on a foundation, pneumatic tests are performed with air or inert gas. Before testing, the device is subjected to a thorough inspection, checking detachable and welding connections. All welds are visible. During pneumatic tests, it is prohibited to tap the device. The tightness of seams and detachable joints is checked using a soap solution. The procedure for increasing and decreasing test pressure depends on the pressure. For example, at a pressure of up to 2 MPa, the duration of pressure reduction is 30 minutes, at a pressure from 5 to 10 MPa - 90 minutes.

The peculiarity of testing horizontal devices is that the loads on the walls of the device from the supports are no greater than the calculated ones. When laying devices on sand pads, it is necessary to dig around the welded seams so that they can be observed.

After completion of all construction and installation work, the work contractors prepare the facility for delivery to the customer. The equipment must be put into operation tested and in a state of full readiness for normal operation.

4. Labor protection

4.1 Safety precautions during installation

When preparing column-type technological devices for installation and before lifting them, work producers check the compliance of the lifting mechanisms, sling ropes, anchors with the work project, as well as the compliance of all lifted loads.

Before lifting, you must make sure that the installed platforms, ladders and pipelines tying the apparatus are reliable, and that the protruding parts of the apparatus and the apparatus themselves do not touch the structures of lifting mechanisms and structures located nearby.

Columns whose mass is close to the lifting capacity of the mechanism should be lifted in two steps. First, the load is raised to a height of 20..30 cm and in this position the suspension and stability of the apparatus are checked. Then the main lift is carried out. The rope must go around the gripping device, and the ratio of the diameter of the gripping device to the diameter of the rope when installing cables and pulleys must be at least 4. Otherwise, thimbles, linings or transition devices are used.

During the lifting process, the deflection of pulleys is controlled (with goniometers)

The inclination of masts, lifts, chevrons (with an inclinometer or theodolite), lifting height and wind speed.

Work is stopped in case of poor visibility and wind speeds exceeding 9 m/s. The devices should be secured against swinging and self-lowering when lifting is forced to stop. It is necessary to ensure that the device does not come into contact with lifting equipment and nearby structures. They lift the load, rotate the platform and move the cranes according to the rigger's signals. The stop signal is executed immediately. The devices are unslinged after they are securely fastened.

It is prohibited to open a grounded and frozen load from the ground, to pull off equipment from supporting structures without lifting it, to drag or pull the load with the pulley in an oblique position, to level, adjust the slings, to pull the load into openings without the use of special receiving platforms, to pull the slings from under the apparatus with using a hook, lift the apparatus together with people and support them with your hands

4.2 Fire safety

At installation sites, current rules, technical standards and fire safety instructions must be observed.

Passages and emergency exits should not be blocked, access to installed fire hydrants, fire extinguisher hoses and sand boxes should be free. In the event of a fire, you must immediately call the fire department and take measures to extinguish the fire, as well as prevent its spread with all available means.

Flammable liquid combustible substances (gasoline, kerosene, etc.) or oily materials are extinguished with foam fire extinguishers or sand.

When the electrical wiring catches fire, the line is immediately de-energized. Burning wooden objects, paper, and protective clothing are extinguished with water from fire hoses.

It is prohibited to use open fire at a distance of less than 20 m from the storage area of ​​flammable substances. It is prohibited to leave switched on electrical appliances and mechanisms unattended.

When producing gas welding and cutting metals, they are guided by the relevant sections of SNiP.

The distance between the portable generator and the metal processing site, as well as the location of the open fire, must be at least 10 m. At the installation site of the portable generator, warning posters and signs “Flammable” and “No smoking” are posted. It is prohibited to install acetylene generators in rooms where there are products that can form an explosive compound with acetylene, as well as in operating boiler rooms, forges and near places where air is sucked in by compressors and fans. In the event of a fire in a gas generator room, only carbon dioxide fire extinguishers should be used to extinguish it.

4.3 Environmental protection

Basic safety provisions. The safety rules that guide the installation of equipment are given in the Construction Norms and Regulations (SNiP Sh-A. 11-70). Installation work must be carried out in accordance with the work project. The work plan provides for the creation of conditions for the safe performance of work both on the construction site as a whole and at individual workplaces.

Control over the implementation of safety measures is assigned to the general contractor; Responsibility for the safe conduct of work performed by subcontractors rests with the heads of these organizations.

Responsibility for compliance with agreed safety measures lies with the administration of the installation organization and the enterprise on whose territory construction and installation work is carried out.

Before starting work, the area of ​​the installation site and workplaces are cleared of construction materials and debris, and in winter - of snow and ice.

Driveways, walkways and crane runways should be kept clean and unobstructed.

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Installation of foundations begins with laying out the axes of the structure and tying them to the terrain. The layout of axes on the ground is carried out by surveyors. The design level of the base of the foundation is determined by a level. After this, the axes of the structure are transferred to the bottom of the pit. The axles are secured to cast-offs. For strip foundations, mainly two structural elements are used: a trapezoidal or rectangular-shaped cushion block placed at the base of the foundation, and wall blocks or panels from which the foundation wall is erected. The basis for strip foundations is a sand bedding, which is laid on protected or compacted crushed stone soil at the bottom of a pit or trench. The installation of strip foundations begins with the laying of lighthouse blocks, which are verified and installed in strict accordance with the axes of the walls of the structure. Lighthouse blocks are installed at a distance of no more than 20 m from each other. Corner blocks and intersection blocks are always lighthouse blocks. A mooring cord is secured along the inner and sometimes along the outer edge of the lighthouse blocks. At a height of 20-30 cm from the installation site, the block is oriented and lowered into the design position. Permissible deviations from the design position when installing strip foundations from prefabricated reinforced concrete blocks should be no more than (mm):

• Markings of supporting surfaces... 10
• Structure axes... 20
• Width of the walls... 15
• Opening width... 15
• Surface and corners (from vertical), for the entire building... 15
• Separate rows of blocks (from horizontal), 10 m long... 15

Pillow blocks are laid one against the other or (if the base has good load-bearing capacity) with gaps that can reach up to 40-50 cm. Pillow blocks are laid along the entire perimeter of the building or within one section. For the passage of pipelines and cable entries when continuously laying pillow blocks, special mounting holes are left.

Blocks or panels of foundation walls are installed at the design marks, filling the joints with cement mortar. Basement panels are usually welded to embedded elements in cushion blocks. During the installation process, wall elements are aligned both relative to the longitudinal and vertical axis. After installing all the blocks, a leveling layer (mounting horizon) of cement mortar is arranged along the upper edge of the wall, the surface of which is brought to the design level. The installation work of the zero cycle is completed by installing the plinth and ceiling above the basement or underground. Strip foundations are usually installed with a crane standing at the planning level, and not in the pit.

Installation of precast concrete foundations begins with a slab. After installing it in the design position, a bed of cement mortar is arranged on the slab, on which a glass block is installed. To connect the glass to the plate, embedded parts are used. After welding the embedded parts, they are protected with an anti-corrosion coating. Installation of the foundations of industrial buildings, made in the form of a single block, is carried out using a crane. The foundation blocks are aligned to the design position by weight, after which the block is lowered onto the prepared site and verified against the axle marks, aligning them with the pins or marks that secure the position of the axes on the base. If the installation is incorrect, the block is lifted, the base is corrected and the installation procedure is repeated again. The correct installation of foundations vertically is checked with a level.

Reinforced concrete columns are mounted as follows. Before installation, check the position of the transverse and longitudinal axes of the foundations and the marks of the supporting surfaces of the foundations, the bottom of the glasses, the dimensions and position of the anchor bolts. Before installation, axial marks are applied to the columns on four edges at the top and at the level of the top of the foundations, and for columns intended for laying crane beams along them, in addition, the marks of the beam axes are applied to the consoles. Columns of industrial buildings are installed by first laying them out at the installation site, or directly from vehicles. The columns are laid out in such a way that during the installation process it is necessary to do a minimum of movements and various auxiliary work and there is free access for inspection, mounting of equipment and slinging. Columns in the installation area are laid out according to various patterns. With a linear layout, the columns are laid out in one line parallel to the axes of the building and the movement of the crane. This layout is carried out provided that the length of the column is less than the pitch of the foundation. When laying out with ledges, the columns are placed parallel to the axis of the structure being mounted and the axis of the crane's penetration. An inclined layout is used when the layout area is limited in size; The centered layout scheme is characterized by the fact that the rotation trajectory of the crane boom during the installation operation is a one-way arc. The columns are not laid out flat, but so that during the lifting process the bending moment from the weight of the column and equipment acts in the plane of greatest rigidity of the column. This is especially important to consider when installing two-branch columns. When laying out, you should take into account the method in which the installation will be carried out. It is more convenient to lift rectangular and two-branch columns from an edge position. Since the column can arrive at the site in a flat position, the first operation during installation is tilting it onto the edge. After laying out, the columns are inspected, checking their integrity and dimensions. At the same time, check the dimensions and depth of the glass under the column. Then the column is constructed with ladders, fixtures, braces, etc.

The conditions for ensuring the correct position of the column during installation are provided for in the installation project. When lifting columns by turning, the lower end of the column is usually secured in a special hinge fixed to the foundation. When lifting columns by turning with sliding, the lower end of the column is hingedly attached to a special trolley, to a slide, or equipped with a spacer and a roller. Columns are slung with various friction grips, pin grips with local or remote slinging, and when installed from vehicles - with balancing traverses. You should strive to ensure that the column hangs on the crane hook in a vertical position and does not have to go up to unsling it. Friction grips are put on the column with the beam removed. After installing and securing the beam, the column is raised. The grip holds the column due to the friction that occurs between the beams and the surface of the column when the cables are tensioned.

Holes for pin grips must be provided during the manufacturing process of the columns. A cable is used to unfasten pin grips used for lifting light columns; To unfasten heavy columns, the grippers are equipped with electric motors. Columns are mounted from vehicles by rotating in weight. To reduce the length of the crane boom during mass installation of columns, booms equipped with a forked head are used. Lifting a column (transferring it from a horizontal to a vertical position) consists of three sequential operations:

• transferring the column from horizontal to vertical position;
• feeding the column to the foundation in a raised position;
• lowering the column onto the foundation.

The column is lifted in one of the following ways:

• the crane moves from the top of the column to its base and simultaneously lifts the hook. The column gradually rotates around the supporting rib. To prevent slipping, the shoe is reinforced with a guy rope. The movement of the crane and the lifting of the hook are carried out in such a way that the cargo pulley is in a vertical position at all times;
• the crane is stationary. Simultaneously with the lifting of the hook, the column shoe mounted on the trolley or the guide rail track lubricated with grease moves towards the vertical. These two methods are used primarily when lifting heavy columns and using cranes that cannot move with a suspended load;
• the crane is installed in such a way that the slinging point and the lower end of the column are at equal boom radii. The column is lifted by turning the boom while simultaneously operating the cargo pulley, which must always be vertical. The top of the column and the place of slinging describe spatial curves. This lifting method is used mainly when installing light and medium-sized columns with jib cranes.

After lifting and installing the column in place, without releasing the crane hook, they begin to align their position. Lightweight reinforced concrete columns are aligned using mounting crowbars and wedges placed in the foundation glass, and special mechanical wedges. The correct position of the columns in plan is achieved by combining the axial marks on the column with the axial marks on the foundation. The position of the columns is checked with a theodolite and a level.

Immediately before the installation of columns in glass-type foundations, a leveling layer is laid to fill the gap between the bottom of the glass and the lower end of the column. The preparation is made of rigid concrete, laid in a layer, the thickness of which is determined by measuring in situ the mark of the bottom of the glass and the length of the column. After installation, the column compresses the fresh preparation with its weight; This ensures uniform pressure transfer to the bottom of the glass. Another way to secure columns is as follows. On the foundation, the bottom of which is not concreted to the design level by 5-6 cm, a support frame is installed, verified and securely fastened. To create the base surface, a forming device is used that has special stamps and a vibrator. Then concrete is placed at the bottom of the glass and the forming device is lowered, directing its bushings onto the fingers of the support frame, then the vibrator is turned on. Lowering under its own weight until it stops, the stamp of the forming device squeezes out imprints of a certain shape in the concrete at the required level, strictly oriented relative to the axes of the foundation; the excess concrete is squeezed upward, after which the forming device is removed and transferred to the next foundations. The use of this method requires the manufacture of columns with increased accuracy.

Short columns of multi-story buildings can be raftered close to their top. As a rule, it is impossible to sling reinforced concrete columns of one-story buildings at the upper end, since its resistance to bending may be insufficient. In most cases, slinging of such columns is carried out at the level of the crane console. In this case, during the turn, the lower end of the column rests on the ground and bends like a single-cantilever beam. The raised column must be vertical. To do this, you need to hang it from a point located on a vertical line that passes through the center of gravity of the column. For lifting, a traverse with grips or slings covering the column on both sides is used. If the bending strength of the column is insufficient, increase the number of suspension points.

Methods for temporarily securing columns after installation in the design position depend on the design of the support of the columns and their dimensions. Columns installed on glass-type foundations must be cemented immediately after installation. Until the concrete has acquired 70% of the design strength, subsequent elements cannot be installed on the columns, except for mounting ties and spacers that ensure the stability of the columns along the row. Columns up to 12 m high in foundation cups are temporarily secured using wedges and jigs. Wooden (hardwood), concrete and welded wedges are used; depending on the depth of the foundation glass, the wedges should be 25-30 cm long with a slope of no more than 1/10 (the length of the wedges is approximately taken to be half the depth of the glass). One wedge is placed at the edges of columns up to 400 mm wide, and at least two at the edges of greater width. Wooden wedges should be used only for small volumes of work, as they make it difficult to seal joints and are difficult to remove. Wedges are used not only to clamp the column in the glass, but also to slightly shift it or rotate it in plan if it is necessary to point it at the alignment axes. Rigid conductors are used to temporarily secure columns. Temporary fastening of columns with a height of more than 12 m with conductors is not enough; they are additionally secured with braces in the plane of greatest flexibility of the columns. Columns over 18 m high are braced with four braces. These devices must simultaneously provide stability along and across the row. The first two columns are braced crosswise with braces, the subsequent ones - with crane beams. Reinforced concrete columns of frame buildings are secured by welding, as a rule, after installing the crossbars and welding the embedded parts of the columns and crossbars. Installation of crane beams is carried out after installation, alignment and final fastening of the columns. Installation begins after the concrete at the joint between the column and the foundation walls reaches at least 70% of the design strength (exceptions to this rule are specifically stipulated in the work project, which simultaneously indicates measures to ensure the stability of the columns during the installation of crane beams and other elements). Before installation on the ground, the condition of the structures is inspected and the joints are prepared. The beams are slung with ordinary slings using mounting loops or in two places “on a noose” with universal strapping slings and suspended from them to a traverse, the size of which is selected depending on the length of the beams. Lifting of crane beams due to their large length (6-12 m) is most often carried out using special or universal traverses or two-leg slings equipped with safety corners. When choosing a grip for a particular structure, you should pay attention to the nature of the reinforcement of the beam flange and the installation conditions. Thus, it is impossible to use pincer grips for the installation of crane beams, the shelves of which are not capable of withstanding the bending moment from the installation load. It is advisable to install crane beams with crane rails attached to them before lifting (with a beam length of 12 m). The rails are fixed temporarily; final fastening is carried out after installing the beams and aligning the position of the rail. When aligning, check the position of the beams along the longitudinal axes and the mark of the top flange. To install beams along the longitudinal axes, marks are applied to the column supports, and marks in the middle of the wall are placed on the upper planks and ends of the beams.

During the reconciliation process, the risks are aligned. The position of the crane beams during their installation is adjusted using a conventional installation tool, and after they are laid out on the support consoles, without resorting to the installation mechanism, using special devices. After alignment, the embedded parts are welded and the beam is unfastened. When installing beams, the following deviations are allowed; displacement of the longitudinal axis of the crane beam from the alignment axis on the supporting surface of the column ±5 mm; marks of the upper flanges of beams on two adjacent columns along a row and on two columns in one cross section of the span ±15 mm.

Rice. 38.

The installation of beams and roof trusses in industrial buildings is carried out separately or combined with the installation of roof slabs (Fig. 38). When preparing trusses for lifting, the heads of the columns and support platforms of the truss trusses are cleaned and aligned, and axle marks are applied. To align and temporarily secure the trusses, scaffolding is arranged and the necessary devices are installed on the columns. The process of installing trusses includes delivering structures to the installation site, preparing for lifting trusses, slinging, lifting and installation on supports, temporary fastening, alignment and final fastening in the design position. The trusses are installed in the design position in a sequence that ensures the stability and geometric immutability of the assembled part of the building. Installation is usually carried out “on a crane”, which sequentially retreats from parking lot to parking lot. Slinging of trusses is carried out using traverses, the slings of which are equipped with locks with remote control for unslinging (slinging of reinforced concrete trusses in order to avoid loss of stability is carried out at two, three or four points). To ensure stability and geometric immutability, the first installed truss is secured with braces made of steel rope, and subsequent ones - with struts attached with clamps to the upper chords of the trusses, or with jigs. For trusses with a span of 18 m, one spacer is used; for spans of 24 and 30 m, two spacers are used, which are installed at 1/3 of the span. With a truss pitch of 6 m, the spacer is made of pipes, with a pitch of 12 m - in the form of a lattice girder made of light alloys. The spacers are attached to the truss before lifting begins. A hemp rope is tied to the free end of the pipe, with the help of which the spacer is lifted to the previously installed truss for connection to the clamps installed there. The spacers are removed only after the trusses have been finally secured and the covering slabs have been laid. The first trusses in the span are secured with cables. When installing lanterns, their structures are attached to the trusses before installation and lifted together with the truss in one step.

After temporary fastening, the lantern is installed in the design position. Trusses are verified according to the risks present on the supporting platforms of the trusses and columns, combining them during the installation process. To secure the trusses in the design position, the embedded parts in each support unit are welded to the base plate, which in turn is welded to the embedded parts of the column head. The anchor bolt washers are welded along the contour. The first two trusses in the span must have a fence or special scaffolding for the period of installation of the covering slabs. Rafter beams and trusses are unfastened only after they are finally secured.

The installation of the covering slabs is carried out in parallel with the installation of the trusses or after it. Installation of the coating can be carried out according to two schemes:

• longitudinal, when the slabs are mounted by a crane moving along the span;
• transverse, when the crane moves across the spans. In this case, when selecting cranes, it is necessary to check whether the cranes can pass under the mounted trusses or crane beams.

When installing roof slabs on tall buildings, it is advisable to equip cranes with special mounting jib. Sometimes, during the installation of covering slabs, which is carried out after the installation of trusses, it is advisable to use special roof cranes that move along the mounted slabs. Before installation, the coating slabs are placed in stacks located between the columns, or they are delivered on vehicles directly for installation. The order and direction of installation of the slabs is indicated in the work project. The sequence of installation of the slabs should ensure the stability of the structure and the possibility of free access for welding the slabs. The location of the first slab must be marked on the truss. In clerestory coverings, the slabs are usually laid from the edge of the roof to the clerestory. For slinging coating slabs, four-legged slings and balancing crossbeams are used, and when using heavy-duty cranes, crossbeams with daisy-chained suspension of the slabs are used. The laid covering slabs are welded in the corners to the steel parts of the rafter structures. The plates located between the first two mounted trusses are welded at four corners; located between the second and third trusses, as well as subsequent ones: the first during installation - in four corners, the rest - only in three, since one of the corners of each slab (adjacent to previously installed slabs) is inaccessible for welding. It is recommended to install the slabs:

• on reinforced concrete trusses with a lanternless covering - from one edge to the other;
• along reinforced concrete trusses with a lantern - from the edges of the covering to the lantern, and on the lantern - from one edge to the other.

Installation of the first slab at the edge of the covering is carried out from suspended scaffolding, and subsequent slabs - from previously installed ones. The joints between the coating slabs can be sealed simultaneously with installation or after it, unless there are special instructions in the work plan.

Installation of floor panels in multi-storey buildings is carried out using the main installation mechanism, and in brick buildings - using a crane, which provides the supply of materials for masonry. To lift floor slabs, balancer-type slings or traverses are used, which make it possible to impart a slight slope to the panel suspended on the crane hook. Floor panels in multi-storey frame buildings are laid in the same flow with the rest of the structures or upon completion of the installation of columns, crossbars and purlins within a floor or section on a floor. The installation of floor panels begins after the walls have been erected in frameless buildings and spacer plates have been laid and secured, as well as purlins or crossbars in frame buildings. Installation begins from one of the end walls after checking the mark of the supporting plane of the top of the walls or crossbars (if necessary, they are leveled with a layer of cement mortar). The panels are lifted with a four-leg sling or a universal traverse. Room-sized panels are slung using all mounting loops. If the panels were stored in a vertical position, then before slinging they are transferred to a horizontal position on the tilter. Using a universal sling, the slab is lifted from a panel carrier or from a pyramid without a tilter. The first one or two slabs are installed from mounting scaffolding tables, and the subsequent ones - from previously laid slabs. If the panels are laid on a surface leveled with a screed, then the bed is made of plastic mortar 2-3 mm thick. When laying panels directly on parts, the bed is made of ordinary mortar. If necessary, the panels are upset by squeezing out the solution during their horizontal movements. When installing the panel on the mortar, special attention is paid to the width of the supporting platform, since it is prohibited to move the laid panels in the direction perpendicular to the supporting structures.

The sagging panels are reinstalled, increasing the thickness of the mortar bed. The thickness of the seams between adjacent panels is determined by sighting along the seam. If the plane of the panel is curved, it is laid at the junction with walls or partitions so that the free edge is horizontal. A panel with a sagging middle is installed on a thick bed so that the sag is divided in half between adjacent slabs. In multi-storey frame industrial buildings, first of all, so-called “spacer” slabs are installed, located along the longitudinal axes of the building, and panels located along the walls. The order of installation of the remaining slabs can be arbitrary if it is not dictated by the project. Strapping is carried out immediately after installing the panel in the design position.

Installation of wall panels is a separate stage of installation work in industrial construction. It begins only after completion of the installation of load-bearing structures in the structural block of the building. In frame buildings, the middle of the frame columns is most often taken as the position of the building axes. When installing an internal wall panel between columns, from their middle, a distance equal to half the thickness of the panel plus the length of the template (usually 20-30 cm) is laid on the ceiling using a meter; this is done so as not to accidentally destroy the risk, for example, when making a bed. If the panels do not fit with the columns, then a mooring is pulled along the plane of adjacent columns, the required size is laid out along it, and the position of the panel plane is fixed with two marks on the ceiling, taking into account the length of the template. For panels adjacent to columns, for example, shear walls, marks that fix the position of the panel surfaces are applied to the column at a distance of 20-30 cm from the floor and ceiling. To install panels of external walls adjacent to columns, for example in one-story industrial buildings or multi-story buildings with blank walls in several tiers, the height marks of the seams of each tier are marked on the columns using a tape measure along the entire height of the column. In large-block and large-panel buildings, in which the walls bear vertical constants (from the weight of the building, equipment) and operational loads, markings are carried out using geodetic instruments. First, the main axes are transferred to the installation horizon; For basement walls, cast-off is used; for subsequent floors, the method of inclined or vertical sighting is used.

Installation of wall panels in frame buildings is carried out in a certain sequence. Internal wall panels are installed during the installation of the building before installing the ceiling of the overlying floor. The shear walls are secured immediately after installation in accordance with the design. External wall panels, which ensure the stability of the frame structures, are also installed during installation with a lag of no more than one floor. Wall panels that do not affect the stability of the frame are most often mounted vertically in single-story buildings and horizontally in multi-story buildings. In heavily framed industrial buildings, exterior wall panels are usually installed in vertical strips. In multi-storey civil buildings, external wall panels are supplied during installation by the same crane as the frame elements. In industrial one-story and multi-story buildings with a heavy frame, external walls are mounted in a separate flow using self-propelled cranes. Wall panels of all types are usually slung with a two-leg sling. When installing multi-story frame buildings, the length of the sling branches must be such that the hook and lower block of the crane pulley when installing the panel are higher than the ceiling of the next floor. The supply of wall panels to the installation site in frame buildings is complicated by previously installed frame structures, therefore, when lifted, the wall panels are kept from turning around and hitting the structure with two hemp rope guys. The panel is installed on the bed vertically or with a slight slope towards the outside of the building to ensure that the panel rests tightly on the bed solution. External strip panels are attached to the columns with two corner clamps; wall and blind area panel - with struts to the floor slabs. The same devices are used to bring the panel vertical in the plane of the wall. To check the verticality of the panels, a plumb line is most often used. Before removing the slings, the bottom of the panel is secured by welding. The panels are finally secured by welding them to the frame elements.

If the panels are mounted before installing the purlin or crossbar, when slinging, two guys from hemp rope are tied to the panel of such a length that when the panel is fed 1.5 m above the top of the columns, the end of the guy is on the ceiling. The panel is lowered between the columns, rotated 90 degrees from the design position, and temporarily secured with a tray clamp or a clamp to the column. The verticality of the panel is checked using a plumb line and the marks on the column. If the crossbar is installed, the strapped partition cannot be placed under the crossbar, so the top of the panel is reattached during its installation. To do this, holding the panel by the guys, it is lowered next to the crossbar and stopped at a height of 10-15 cm from the ceiling. Pressing the bottom of the panel, install it on the mortar bed. If necessary, correct the position of the bottom of the panel. The top of the panel is temporarily secured with a chain or clamp. The chain is passed through the mounting loops of the panel and wrapped around the crossbar, the open ends are connected. Window panels are installed during the installation of wall panels or after their installation. Window panels are installed one above the other, resting them on support consoles made of large profile corners (150-200 mm), welded to columns or to embedded parts. Window panels are often mounted in large blocks. Sometimes they are enlarged together with half-timbered structures and imposts. To do this, the bindings are assembled and attached below to the half-timbered elements. Lantern top-hung frames are mounted from the covering slabs manually or using blocks and winches, and secured from ladders or leaning ladders.

Installation of walls of large-block buildings is carried out within the area after completion of installation of all structures of the underlying tier. Blocks, as a rule, are slung with a two-legged sling using two mounting loops. Tall wall blocks, if they are stored in a stack in a horizontal position, are first transferred in the same position to the site, where they are transferred to a vertical position.

It is impossible to tilt blocks directly in a stack, since if the lower edge of the block slips, the jerk of the crane boom can lead to an accident. If, when installing the upper floors of a building, light blocks are slung with a four-branch sling, supplying two blocks per floor at a time, then while the first block is being installed, the second one is temporarily placed on the floor above one of the internal load-bearing walls. If two textured blocks of external walls are lifted, then the inner edges of the blocks must touch each other during lifting. The mortar bed is arranged on the cleaned base. The beacons are placed near the outer edge of the block at a distance of 8-10 cm from the side edges. The correct installation of the top of the block is checked by the mooring and by sighting on previously installed blocks. The horizontality of the top of the block in the longitudinal direction is controlled by a rule with a level and sighting on previously installed blocks. The correct installation of the top of the lintel block is checked by measuring the distance from the mark of the top of the block to the supporting quarter of the lintel with a meter or template, and the lighthouse blocks of the internal walls - to the top of the block. The top of the gable blocks is checked using a mooring stretched along the gable slope.

Minor deviations in the position of the block along the pediment are corrected by shifting it along the longitudinal axis of the wall. It is impossible to move jumper blocks along the walls, as this may cause displacement of the blocks of the lower tier. Installation of external wall panels of large-panel buildings begins:

• basement walls - after installation of foundations;
• walls of the first floor - after completion of work on the underground part of the building;
• on the second and subsequent floors - after the final fastening of all structures of the underlying floor.

On the installation horizon, two beacons are installed for each side panel at a distance of 15-20 cm from the side edges. For external wall panels, beacons are located near the outer plane of the building. The panel supplied by the crane is stopped above the installation site at a height of 30 cm from the ceiling, after which the panel is directed to the installation site, while ensuring that the panel is lowered correctly into place. The correct installation of the external wall panels in place is checked along the cut line of the walls of the underlying floor.

Installation of load-bearing panels of internal walls is carried out in the same way as external ones, with the installation of two beacons. Non-load-bearing panels and partitions are installed directly on the solution. When installing gypsum concrete partitions, before installing the bed, a strip of roofing felt, roofing felt or other waterproofing material 30 cm wide is placed on the base; The edges of the strips, bent upward when installing floors, protect the partition from moisture. Installation of cross-wall panels on the mortar and alignment is greatly facilitated if the design provides for inserting the panel into the groove at the junction of the outer panels. The end ribs of the outer panels in this case serve as guides. To temporarily fasten the end of the panel adjacent to the outer wall, it is wedged; The free end of the panels and partitions is secured with a triangular stand; a screw device at the top of the stand makes it easier to adjust the panel into the plane of the wall. If the panel only adjoins the panels of the internal walls, the adjacent end is temporarily secured with a spacer or corner clamp.

Installation of reinforced concrete shells for public buildings (transport, sports, entertainment, shopping facilities, etc.) is carried out using two main technologies for installing prefabricated monolithic shells:

• at ground level - on the conductor with subsequent lifting of the fully assembled shell to the design mark using installation cranes;
• at design marks.

The main method is the installation of prefabricated shells at design marks, which is carried out on mounting supporting devices or with the support of enlarged shell elements on the supporting structures of the building - walls, contour trusses, etc.

A long cylindrical shell measuring 12x24 m is assembled from side elements in the form of gable pre-stressed beams and curved slabs measuring 3x12 m. Installation of the building frame begins with the installation of columns. Depending on the parameters of the installation crane, two options for organizing the installation are used: in the first case, the crane beams are installed immediately after the installation of the columns in a separate stream, and the installation of the shell is carried out by a crane located outside the span of the shell being mounted; in the second, the assembly is carried out by a crane moving inside the span of the building being assembled. After laying the side elements, temporary tubular supports are installed under the side elements, since before the joints are grouted they are not able to absorb bending forces from the weight of the separately lying shell elements. The enlargement of end plates with tightening is carried out on enlargement stands. After installing all the elements, the fittings are welded and the joints are sealed. Spinning is carried out after the concrete in the joints reaches 70% of the design strength.

Installation of free-standing shells (free-standing shells mean shells measuring 36x36 and 24x24 m from slabs measuring 3x3 m, the shell of which is supported by four diaphragm trusses that are not structurally connected to adjacent shells) is carried out using conventional installation cranes. Such shells are assembled on special devices - inventory mobile conductors. The conductor moves along railway tracks installed on a solid base - concrete preparation, prefabricated slabs, a layer of ballast. When constructing a building with several shells, the complete assembly of the conductor is performed once, and then the conductor is moved to the next cell. The installation of the shell begins with the installation of a diaphragm truss located at the end of the span, then a second truss is installed along the outer wall. The trusses are secured together with spacers and secured with guy ropes. After this, the conductor is assembled, installing support trolleys, racks, two load-bearing trusses and lattice girders. After alignment and temporary fastening of the conductor with rigid connections between the trolleys (guys - behind the columns and spacers - to the trusses), part of the purlins is removed and a third contour truss is mounted, which, after alignment, is attached to the conductor with spacers. After this, the crane is moved into the span and installation of the corner slabs of the shell and then the remaining slabs in the established sequence begins. The slabs are laid on the support tables of the conductor’s pre-calibrated lattice purlins. After installing half of the shell slabs, the crane exits the cell, replaces the previously removed purlins and then installs the fourth contour truss. The remaining slabs are mounted in a similar mirror sequence.

During the construction of multi-span industrial buildings covered with double-curvature shells measuring 36x38 or 24*24 m, inventory conductors are used that move from position to position on rails. In a span or simultaneously in several spans, conductors are installed and then raised to the design marks, which are mesh circular structures that repeat the contours of the shell. Contour shell trusses are installed on the columns using assembly cranes. After laying the prefabricated slabs, which is done from the contours of the shell to the center, and adjusting their position, the butt joints are welded and the seams are sealed. After the concrete at the joints reaches 70% of the design strength, the shell is turned around, the conductor is lowered into the transport position and moved along the rails to an adjacent position.

The installation of multi-wave shells measuring 18x24 m from 3x6 m slabs has the peculiarity that adjacent shells rest on a common contour truss 24 m long, and along the upper belt of 18-meter contour trusses, adjacent shells are monolithic. When constructing a two- or three-bay building, installation is carried out on two or three conductors. The procedure for assembling and installing conductors is the same as for free-standing shells, but the assembly order is different: first the first conductor is installed, then two 18-meter diaphragm trusses are placed and attached to it - one extreme and one middle (in a single-span building - both extreme) and a 24-meter extreme truss. Walking scaffolding and elements of steel inventory formwork are installed on 18-meter trusses before lifting. After installation, alignment and fastening of the trusses, the corner zones are welded and the shell elements begin to be assembled. When constructing a multi-span building, after securing the trusses of the first shell, trusses of adjacent shells are installed. To avoid tipping over, they are secured together with rigid spacers, welded in the corner areas to the embedded parts of the upper chords. Thus, it is possible to install conductors in the remaining spans. The installation of the shell begins with laying the corner slabs, then installing the contour slabs of the far row and the middle one. Row slabs are laid on the conductor beams. After installing the middle row of slabs, a 24-meter truss is installed, and then the last row of slabs is laid, which are mounted through the installed truss. After this, the outlets of the reinforcement and embedded parts are welded. Before grouting the joints, the first row of slabs must be installed in the adjacent shell. The grouting of joints begins from the corner zones and the junction of the slabs with 18-meter trusses, and the remaining joints are grouted in the direction from the 24-meter trusses to the vault shelya.

Shells of double positive curvature with dimensions of 18x24, 24x24, 12x36 and 18x36 m are mounted in enlarged blocks assembled on stands from 3x6 or 3x12 m panels. The panels are assembled into an assembly block on a stand by welding embedded parts and fastening with temporary mounting ties. The length of the enlarged block corresponds to the span of the shell. After this, the block is installed by crane in the design position on the pre-assembled side elements.

Byte suspended coverings are a type of reinforced concrete shells. They consist of a reinforced concrete contour with a mesh of steel ropes (cable cables) stretched over it and prefabricated reinforced concrete slabs laid over them. The byte network consists of longitudinal and transverse steel ropes located along the main directions of the shell surface at right angles to each other. The ends of the cables are anchored using special sleeves in the supporting reinforced concrete contour of the shell. When installing suspended coverings, a cable-stayed network of steel ropes is stretched onto the reinforced concrete contour, ensuring the design curvature of the shell. Then prefabricated reinforced concrete covering slabs are laid along the ropes and their temporary loading is in the form of uniform filling of the shell with a piece load, the weight of which is taken equal to the weight of the roof and the temporary load. After this, the seams between the prefabricated shell slabs are sealed. After the concrete reaches its design strength, the temporary load is removed. Thus, prestress is created in reinforced concrete slabs, and they are included in the overall work of the coating, which reduces the deformability of the suspended structure.

Prefabricated reinforced concrete structures are manufactured in factories and only then delivered to the construction site. On the one hand, by scaling up production, this can significantly reduce the cost per unit of production; on the other hand, the designer must set clear parameters for the future product.

Prefabricated reinforced concrete structures make it possible to erect entire buildings in the shortest possible time, but the ability to modify products during operation is extremely limited and is associated with considerable financial costs.

There are types of reinforced concrete structures that are manufactured only in factories. As an example, prestressed SLCs. Typically, enterprises produce only standard products. Of course, it is possible to order individual parameters, but you have to pay extra for uniqueness. Conventionally, all production technologies can be divided into three types:

• conveyor technology,
• flow-aggregate technology,
• bench technology,

For prestressed precast structures, the following production methods are used: tension on concrete and tension on supports. The reinforcement is tensioned using electromechanical and electrothermal methods.

General characteristics

The characteristics of precast concrete structures depend on the grade of concrete and the type of reinforcement that is used in them. Concrete has the following quality parameters:

• frost resistance,
• strength,
• high density,
• fire resistance.

The only drawback of concrete is its poor tensile strength. To level it, reinforcement is used. It can be made of composite or steel. The shape may vary, but in most cases ribbed steel rods with a circular cross-section are used.

Installation process

At the beginning of installation, the condition of already installed precast concrete structures is checked. The further algorithm of the process directly depends on the type of LCC and the goals pursued by the builders. Nevertheless, there are points that are always present in the work:

1. Inspection of precast concrete structures to be installed. Builders must ensure that the embedded parts are positioned correctly and that the anti-corrosion coating is not damaged. Particular attention is paid to the reinforcement; it must not be damaged or deformed.
2. Design and installation holes are checked. Their diameter must correspond to the indicators in the project. A tape measure or meter is used for measurements.
3. Precast concrete structures are examined for cracks and cavities. The geometric shape of the product must correspond to the design one.
4. After inspection, all precast concrete structures are cleaned. Parts deformed during transportation are straightened. The influx of concrete is removed and rust is cleaned off (if any was found).

Prefabricated reinforced concrete structures can be slinged using different methods during installation. Load-lifting means can be in the form of traverses, flexible slings or vacuum grips.

Advice ! It is most convenient to work with lifting devices that have a detachable remote hook.

SNiP 52-01-2003, edited in 2012

SNiP is a set of rules that includes a set of standards and recommendations regarding the production, design, installation and transportation of prefabricated reinforced concrete structures.

Prefabricated reinforced concrete structures, despite their high strength, must be transported in accordance with established standards. When an LCC is designed, the impact of forces that occur during lifting, transportation and installation is taken into account. In this case, the load depends on the mass and is calculated using the following coefficients:

• 1.4 - for installation;
• 1.6 - for transportation;
• 1.25 - dynamic coefficient.

The last indicator is an illustration of the limit figure below which the coefficient cannot fall in calculations. Otherwise, the reliability and durability of the precast concrete structure will become questionable.

Nodal and butt elements play a special place in the design process of prefabricated reinforced concrete structures. The performance characteristics of the entire prefabricated structure depend on their quality.

In precast concrete structures, hinges play an important role. When creating them, according to SNiP 52-01-2003, it is customary to use hot-rolled reinforcing steel. Moreover, its class must be no lower than A240.

Important ! When creating loops for SLC, the use of St3ps steel is unacceptable.

If you have ever dealt with monolithic reinforced concrete structures, then you know very well that they cannot be installed at sub-zero temperatures without special equipment. SLCs do not have this drawback. According to SNiP, they can be installed when it is -40 outside. This will in no way affect their performance.

Characteristics of prefabricated reinforced concrete structures according to SNiPs

Reinforcement plays a special role in the characteristics of prefabricated reinforced concrete structures. To achieve an optimal result, it is necessary to accurately calculate the distance from rod to rod and the diameter of the reinforcement itself. It is very important that the steel elements completely hide the concrete. There are special parameters of the protective layer for each type of building:

1. The humidity level is average or low, the type of room is closed - a protective layer of at least 15 mm.
2. At high humidity in enclosed spaces - 20 mm.
3. Outdoors - 25 mm.
4. In the ground and foundation - 35 mm.

To achieve the required quality indicators, it is necessary that prefabricated reinforced concrete structures meet these characteristics. Reducing the protective layer of concrete is possible only with additional protective measures.

If a prefabricated reinforced concrete structure does not have a reliable protective layer for the reinforcement, then there is a high risk that corrosion will reach the prefabricated structure. This compromises the strength of the entire building.

Installation requirements according to SNiPs

When constructing a building from SLC, the role of the designer increases many times over. It is he who, using special programs, must calculate in advance the parameters of the future structure. According to these characteristics, the factory will produce products of the required shape and size.

Installation must take place strictly according to the approved plan. This document provides for the order of work and additional measures to ensure the required strength. Prefabricated reinforced concrete structures are assembled directly on site and installed in the place assigned to them in the project.

Testing the characteristics of LCC according to SNiPs.

Before sending a product to a customer or putting it into production, a whole range of complex tests are carried out. The following characteristics are tested during the process:

• crack resistance;
• serviceability;
• overall suitability assessment.

Testing is carried out by changing the load on the precast concrete structure. In some cases, blocks are deliberately destroyed in order to find out the maximum strength values.

Usually several products are taken from a batch, and they are subject to various types of tests. The choice of the latter largely depends on the purpose of prefabricated reinforced concrete structures. The suitability assessment consists of indicators such as:

• thickness of the protective layer;
• strength of welded joints;
• geometric size of sections and location of reinforcement;
• strength of welds;
• mechanical properties of reinforcement;
• product size.

Based on these indicators, an assessment of the entire batch is formed, and a decision is made regarding its suitability.

Results

Prefabricated reinforced concrete structures are manufactured only in factories. At one time, this gave a significant impetus to the general industrialization of industry. SLC can be installed in any weather, and their cost is at an affordable level.

→ Construction work

Installation of reinforced concrete structures

Installation of structures of one-story industrial buildings. When installing one-story industrial buildings, the longitudinal installation method is used, when the assembly is carried out in separate spans, and the transverse or sectional installation method, when the assembly is carried out on separate sections of the object.

Depending on the width of the building span, the mass of the mounted elements and the load capacity of the crane, its movement when installing structures is carried out in the middle of the span or along its edges. When choosing the movement of the crane, it is necessary to strive to ensure that the length of the paths for its movement and the number of stops are minimal.

Unlike metal frames, which are assembled panel by panel (complex), buildings made of prefabricated reinforced concrete elements are mounted separately, which is determined by the need to seal the joints of structures before installing subsequent elements on them. Installation of covering structures can begin only after concrete has reached 70% strength at the joints of columns with foundations. To hand over the building for the following work in separate parts, the entire scope of work is divided into sections limited by spans, expansion joints or individual sections, depending on the size of the workshop.

When several installation mechanisms operate simultaneously, installation is carried out in several parallel threads.

Prefabricated structures of one-story industrial buildings are assembled, as a rule, by jib cranes in the following sequence: foundation blocks, columns, foundation beams, crane beams, trusses or beams and covering slabs.

In the case of installation of frames of prefabricated reinforced concrete industrial buildings, on-site warehouses are not organized, which is explained by the relatively close location to the installation sites of manufacturing plants and the possibility of delivering structures directly to the installation site.

When organizing the supply of structures in the required sequence and on time, installation is carried out from vehicles (installation “from wheels”). If it is not possible to organize installation "from wheels", the structures are transported by road to the area of ​​the installation crane. Unloading of structures is carried out with a lighter crane, or an installation crane in the third shift, since it is irrational to use the main installation mechanism for unloading and laying out structures during day shifts. To ensure uninterrupted installation, the supply of structures must be at least 5 days.

In Fig. 181 shows a diagram of the installation of a workshop with three spans of 24 m each.

Installation of structures of multi-storey industrial buildings. When constructing multi-storey industrial buildings, horizontal (floor-by-floor) or vertical (in parts of the building to the full height) installation methods are used. In this case, structures are usually installed using an integrated method that ensures the spatial rigidity of each individual part (cell) of the building.

Rice. 181. Workshop installation diagram: 1 - SKG-30 crane with a 25 m boom; 2 - semi-trusses; 3 - stand for enlarging farms; 4 - coating slabs

Installation of prefabricated elements of the underground part is carried out using jib or tower cranes. In this case, tower cranes are installed with the expectation of their use for the installation of the above-ground part of the building without re-laying the crane tracks. Prefabricated structures of the above-ground part are mounted using tower cranes, which are installed on one or both sides (with many spans) of the building, or boom cranes with tower-jib equipment.

The procedure for installing prefabricated reinforced concrete structures of multi-story industrial buildings depends mainly on the structural layout of these buildings. The main condition for the installation of building structures of any structural design is to ensure the stability of the assembled part of the building and its individual elements. The installation of structures of the next floor (tier) begins only after the design fastening of the structures of the previous floor and the concrete has reached 70% strength. These frame construction conditions impose certain requirements on the selection of the mounting mechanism and its installation.

The mounting mechanism must be located outside the frame and move along the building, covering it with its boom. If the building is large and it is impossible to completely cover it on one side, the frame is mounted with two cranes moving along both sides of the building.

The high height of buildings and the floor-by-floor installation method require a large under-boom space, which can be achieved by using a high tower crane or a jib crane with tower-jib equipment.

To reduce the overall construction time and to speed up the delivery of the frame for related construction work, the building is divided into queues. The breakdown of the queue is determined by expansion joints. Each section of the frame is divided into sections within the floor. The number of grips on the floor should not be less than two, so that on the first of them the installation of frame elements can be carried out, and on the second, at the same time, the design fastening of joints and their holding, if necessary, can be carried out. The size of the grips is determined from the condition of equal duration of work on each grip, so that there is no downtime of the crane.

Rice. 182. Installation diagram of a multi-storey industrial building: 1 - frame; 2 - tower cranes BK.SM-14

Unlike single-story buildings, elements in multi-story buildings made of prefabricated reinforced concrete structures are assembled in a complex manner. First, four columns of one cell are installed, then the crossbars are mounted in this cell and spacer plates are laid in it between the columns. Upon completion of the installation of the elements of one cell, the elements of the other are installed in the same sequence, etc.

During the installation of columns, they are temporarily fixed and aligned using a theodolite. Fastening is carried out using conductors, guy wires or struts with screw couplings, securing them to the sling loops of the underlying slabs and crossbars. Conductors are used single or group (for two or four columns). Conductors are moved from one place to another, as well as to the floors of the building under construction, using installation cranes. After temporary fastening and verification of the correct installation of the columns, they are finally secured by electric welding of the embedded parts. The column joints are welded before installing the remaining frame elements. The fastening of crossbars to columns and slabs to crossbars is also carried out by welding embedded steel parts.

In Fig. 182 shows the installation diagram of a multi-storey industrial building.

Installation of power line supports. In the construction of power transmission lines (PTL), along with metal and wood, prefabricated reinforced concrete supports are also widely used. The supports are delivered from the factory to their installation site by rail or road transport. Moreover, the support is equipped with traverses, a cap and other parts before sending it to the picket. Loading, transporting and unloading reinforced concrete supports are carried out with extreme caution, as they are easily damaged. Loading of long racks is carried out using mounting crossbars. When transported by rail, long racks are loaded onto couplings from three platforms, and are rigidly tied only to the middle platform; on the outer platforms, the racks are laid on wooden pads without being tied down to ensure that they can slide on curved sections of the track. When transporting on vehicles with semi-trailers, channels are used as supports.

Reinforced concrete support racks, delivered to the picket without traverses, are connected to steel traverses by means of bolts, which are passed through holes in the corners of the traverse and through steel tubes embedded in the rack during its manufacture. Fastening can also be done with steel clamps covering the rack.

Rice. 183. Scheme for lifting a reinforced concrete power line support

When assembling anchor flat supports on cable guys with two traverses, both racks and traverses are laid out on a leveled area at the installation site. Then the racks are connected to the traverses and the ends of the guy wires are secured. The support assembled in this way has sufficient rigidity to lift it entirely without the use of temporary connections with racks. Reinforced concrete supports with steel traverses are installed suspended using jib cranes. Lifting of supports with heavier reinforced concrete traverses is carried out using a tractor with a falling boom (Fig. 183). Unlike steel supports, the ends of the lifting cable with a reinforced concrete support height of 15 m or more are secured to the rack in two places - under the upper and lower traverses - in order to reduce installation forces in it. At the beginning of the climb, the bottom of the support rests against the wall of the pit, so that the lower brake cable is not required. The brake braces, required at the end of the lift when the boom comes out of service, are attached to the stand under the middle crossbeam.

The main material in the construction industry is concrete. It is used to produce structures and their elements of various types, purposes, in factories, at landfills, directly at construction sites, which form the supporting structure and appearance of structures. Regulatory documents establish practical requirements for the installation process of concrete and reinforced concrete products.

What types of reinforced concrete structures are there?

Products are divided into prefabricated, monolithic, prefabricated-monolithic. The first are factory samples, which are combined into a frame or connected to it by welding and subsequent concreting. The second ones are cast on objects whose frames will take increased loads (foundation slabs, self-supporting frames, etc.).

The latter rationally combine heterogeneous elements of the first and second types. Factory designs are equipped with conventional and (increases resistance to bending loads). Monolithic products contain only conventional reinforcement cage.

SNiP 3.03.01-87, which sets standards for all stages of installation of reinforced concrete structures, technologies and materials. GOST 10922-90, which establishes general conditions for the formation of products from reinforcement and their welding in reinforced concrete structures. GOST 14098-91, standardizing types of structural design, geometric parameters of connections when welding embedded parts and reinforcement. The requirements of the listed documents are included in the project for the execution of work at construction sites (PPR).

How are the structures installed?

Installation of prefabricated concrete and reinforced concrete structures includes:

• intermediate storage and movement of products;
• installation of reinforced concrete products from prefabricated elements;
• reinforcement in monolithic structures;
• pouring and maintaining concrete until it reaches strength;
• concrete processing.

Warehousing and moving

The placement of products on the construction site is carried out taking into account the installation sequence. Products are stacked in stacks (the permissible quantity is individual for a specific type) on pads about 3 cm high, located strictly one below the other, or in group cassettes. The frame components are placed in the installation area (the working radius of the crane's reach without changing its boom radius) of the crane. Changing the boom radius is allowed only for moving floor slabs. Moving of structural components is carried out only by lifting equipment.

The slings are attached to the mounting fittings in accordance with the drawings. Manual carrying of loads weighing up to 50 kg is allowed (dragging is prohibited) over a distance of up to 30 m. Before assembly, it is allowed to lay out components of the same type (columns, beams, etc.) on spacers in order to inspect the condition of the reinforcement outlets. Such structural outlets are protected from damage; attaching slings to them is unacceptable.

Lifting and lowering of loads is carried out with a static hover above the lift-off/installation point at a height of 300 mm. The spatial position of the products must correspond to the design position when installed in the building structure (examples - panels, columns, flights of stairs, etc.). To improve orientation in the air, use one or two guy ropes attached to them. Hardware at the construction site is placed in sorted form in a special room.

Concrete works

The components of concrete compositions are dosed by weight. The volume of water in the solution is a guideline for the volume of modifying additives that change the properties of concrete (frost resistance, plasticity, fluidity, hydrophobicity, etc.). The proportions of the components are determined relative to all batches (grades) of cement and aggregates by and. It is not allowed to increase the workability of concrete by adding water to the mixed mixture. The requirements established by SNiP 3.03.01-87 for the formation of solutions are shown in Table 1.

Places of installation (forms), their seams and surfaces are cleaned of seasonal sedimentary moisture, dirt, debris, oil and grease stains, cement dust film, then washed under pressure and dried. The size of the aggregate grain fractions should not be more than 1/3 of the cross-sectional size of the seam at the narrowest point, and should not exceed 3/4 of the minimum distance between the reinforcing rods. Concrete is poured in layers. Vibrotamping is carried out by immersing the tool to a depth of 50 - 100 mm.

Its support on embedded parts, formwork and reinforcement is unacceptable. The step of movement along the surface is 1.5 times the operating radius of the equipment. Surface action models are rearranged with overlapping compaction areas by 100 mm. Subsequent layers of mortar are poured after the previous layer has gained strength to 1.5 MPa.

Concrete processing

Then it is covered with a cement screed 20–30 mm high, which is coated with a waterproofing compound. is subjected to the formation of technological holes and openings, anti-deformation seams (a set of strength indicators of 50% and above). It is preferable to use diamond cutting tools (vibration loads are excluded) with forced heat removal from the working area.

Reinforcement

It is carried out by installing factory-made flat reinforcing meshes into the formwork, which have longitudinal and transverse components. This reinforcement groups long rods and keeps the transverse ones from deforming. Volumetric connection of layers of structural reinforcement inside the formwork and working reinforcement of different products is carried out using binding wire, welding, screw couplings, crimp sleeves, etc. Before pouring, the quality of metal installation is checked, the form is freed from debris and scale.

The reinforcing structure should be 20 - 30 mm high on all sides. Pouring the solution is accompanied by compaction using bayonet and vibratory rammer. (the ratio of the sum of the cross-sectional areas of the reinforcing metal to the cross-sectional area of ​​the structure) of the lower columns of the building is set to not less than 2.01%, the upper - 0.79%. Metal can fill a concrete structure with no more than 0.1%.