A special type of installation work during reconstruction, which is practically not encountered in the construction of new buildings and structures, should include work on hanging structures: a set of operations aimed at completely removing the loads transmitted to the hanging structures by overlying elements, with separation of the nodal interfaces of the hanging and bearing elements. These works are considered to be the most difficult: they are carried out in conditions of limited intrashop space, in shops that often work non-stop; they are almost always accompanied by a set of works to strengthen the suspended structure in connection with a change in its design scheme of work; their implementation requires special technological equipment and devices manufactured by the installation organizations; it is necessary to provide for measures to ensure the spatial stability of frames for the period of work, etc. However, despite the complexity, hanging structures gives a great economic effect, as it allows you to rebuild individual structural elements without dismantling the overlying structures. During the reconstruction of one-story industrial buildings, various structural elements are hung out if it is necessary to replace, strengthen or rebuild columns and foundations, crane beams, rafters and truss structures. During the reconstruction of foundations, columns with all overlying structures are hung out. The list of suspended structures during the reconstruction of the column depends on the nature of its reconstruction. So, when reconstructing the crane parts of the columns, in some cases it is enough to hang the crane beams, in others, the coating structures are additionally hung out; when reorganizing the over-crane parts, only the cover is hung. The possibility of using the method, as well as a set of constructive and technological measures to strengthen the suspended structures and ensure the spatial stability of the shop frame, is determined by the design organization that developed the reconstruction project according to the initial data issued by the organization developing the PPR. For the duration of the work within the boundaries of the site determined by the design organization, the operation of electric overhead cranes should be prohibited, as well as the operation of technological equipment that transmits dynamic effects to the ground or building structures should be limited or stopped. The limiting gap between the element being hung out and its bearing element is determined by the design organization that developed the reconstruction project. Technological equipment and fixtures must be manufactured according to the drawings issued by the organization that developed the PPR and tested before the start of work. Temporary support supports, and, if necessary, suspended structures, in order to avoid displacement, must be securely fastened with temporary guy wires or struts. It is necessary to ensure reliable pairing of suspended structures with temporary supports. Before starting work, it is necessary to remove caked dust, snow, all foreign objects from the roof of the workshop and, if possible, free the suspended structures from technological industrial wiring suspended from them. During the work, constant geodetic control over the spatial position of the workshop structures should be established. Work on hanging structures is constantly supervised by an engineering and technical worker. Columns are suspended using hydraulic jacks, low and high mounting portals on rigid hangers and props (Fig. 1). The lifting of columns with all above-installed structures using hydraulic jacks, based on the foundation of the columns, is carried out when restoring the design position of the columns, disturbed as a result of subsidence of the base. Prior to the start of work, the supporting nodes of the column are released from concrete and, if necessary, measures are taken to eliminate the adhesion of the base plates to the foundations. Columns should also be freed from wall filling. In some cases, the constructive solution of the walls, their technical condition and the required lifting height make it possible to confine ourselves to clearing the seams of wall panels and cutting the flexible connections between the brickwork and the column.

Fig.1. Hanging the colony with the help of a - hydraulic jacks; b - low portals; in - high portals; g - rigid pendants; d - rigid supports; 1 - crane beam: 2 - hanging column; 3 - braces; 4 - overjack support device; 5 - jack; 6 - base for a jack; 7 - foundation; 8 - low portal; 9 - base for the portal; 10 - high portal; 11 - outlet block; 12 - chain hoist; 13 - winch; 14 - rigid suspension; 15 - rigid support

Resistant tables or jacking beams are pre-attached to the column, and a base for jacks is installed on the foundation surface (a steel sheet or a sleeper cage covered with a steel sheet). Depending on the design solution of the column shaft, the acting loads from the frame structures to the lifting capacity of the jacks, a pair of hydraulic jacks (2, 4 or 6) is installed between the prepared base and the over-jack thrust structure, the operation of which is synchronized by connecting them to the pumping station. To ensure stability, the column is temporarily braced by four diametrically spaced braces attached to the bottom of the column before the column is lifted. In this case, it is necessary to establish instrumental control over the amount of effort in the braces, which should be equal. After that, the column is released from the foundation by screwing the nuts from the anchor bolts by an amount exceeding the calculated value of the lift by 15-20 mm, and it is lifted with hydraulic jacks. As the gap between the column and the foundation is formed, it is filled with steel gaskets, and retaining half rings are installed on the piston rod. The column is raised to a height exceeding the calculated one by 10-15 mm, after which the gaskets are adjusted and fixed or replaced with a special insert. Lowering the pistons of the jacks, they re-support the column on the gaskets, fix the anchor bolts with nuts, remove the jacks, remove the braces and thrust structures. If it is necessary to lift several consecutive columns, these operations are performed in stages, achieving uniform alignment of the sagging group of columns. If it is not possible to install the jacks directly on the foundation (insufficient dimensions, the need to strengthen the foundation), they are supported on jacking beams laid on a prepared base. Depending on the specific conditions and the purpose of the hanging work, the foundation can be made in the form of sleeper cages covered with steel sheet, packages of rolled steel beams, free-standing columnar foundations, as well as foundations on short driven or stuffed piles. If the reconstruction project provides for the replacement of the existing foundation, as well as in the presence of weak soils, channels, underground structures and communications in the column area, hanging is carried out using mounting portals. In this case, depending on the nature of the reconstruction of the foundation and the hanging column, low and high portals can be used. Low ones are used when the work on the reconstruction of the frame is associated with the replacement or strengthening of the existing foundation, high ones - if it is necessary to rebuild the base of the column or its crane part. When using low portals, jacks are used as a lifting device, high ones - hydraulic jacks or chain hoists with winches. The portals are a rigid spatial structure capable of absorbing all mounting and working loads from the hanging section of the shop frame. They consist of four supports connected in the upper part by a beam system, as well as load-bearing and connecting elements that form a working platform. Jacking beams or beams for fastening chain hoists can be both elements of the working platform, and independent, laid on top of the working platform. Due to the fact that portals are used in cases where the frame structures remain suspended for the entire period of the reconstruction of the foundations and lower parts of the columns, i.e. for a relatively long time, they are installed and fixed on special foundations, and the suspended column is re-supported on the portal, rigidly attached to it. After performing work on re-supporting columns on portals, lifting devices (hydraulic jacks, winches) are released from the load.

Re-supporting the hanging column can also be carried out on the existing adjacent columns of the workshop, which are stored for the period of work in the design position. For this purpose, inclined rigid hangers and props of box-shaped, tubular or lattice type are used. The angle of articulation of the hanger with the existing column, and the props with the suspended column, makes it possible to temporarily articulate them. Permanent fastening of props and hangers with suspended and existing structures is recommended to be carried out on high-strength bolts, since the latter form a reliable shear-resistant detachable connection. Since in the considered option of hanging the columns, the loads are transferred to the existing frame structures of the workshop, the lifting device should be the simplest and most suitable for the specific conditions of the work. As a rule, these are hydraulic jacks installed directly on the foundation or jacking beams. Work is performed in this sequence. On the hanging and adjacent columns, kept in the design position, the elements are fixed that form the junction with suspensions or props. Resistant jacking structures are additionally fixed on the hanging column. With the help of a chain hoist, a winch and diverting blocks, an articulated suspension or support assembly is raised and temporarily (articulated) attached to the column. The base is installed under the hydraulic jacks and the suspended column is uncoupled. After that, the junction of the column with the foundation is disconnected and the column is raised by hydraulic jacks to the estimated height. The calculated height is taken to be the height equal to the value of the assigned clearance between the column and the foundation, summed up with the deflection of the suspended column after the load is transferred to the hangers or supports. Then, with the help of a chain hoist, a winch and pull-off blocks, the free end of the suspension (props) is lifted, the holes in the nodal mate are aligned and high-strength bolts are installed, controlling their tension. After the design fixing of the nodes, the pistons of the jacks are smoothly lowered. The described methods of work are also used for temporary hanging of coating structures. However, in a number of cases, these methods are also used to rebuild the existing frame by gradually re-supporting individual structural elements on newly arranged or reinforced existing ones. Most often, such decisions are made when it is necessary to increase the pitch of the columns by removing their lower part.

Recently, designers and installers have developed rational design solutions that allow performing the entire range of work to increase the column spacing without dismantling the coating structures, re-supporting their heads on special supporting structures. There are the following types of such solutions: 1) with the transfer of the load from the hanging column to the adjacent adjacent frames; 2) on supporting beams. The first solution makes it possible to increase the spacing of columns from 12 to 24 m. In this case, it is necessary to create a structure capable of transferring to the outer columns the load that is perceived by the middle column and removing its lower part. If the existing height dimension allows the use of 24-meter trusses for this purpose, located below the crane beams, then the trusses are located in the plane of the branches of the columns, while each truss consists of two planes covering the branch of the column. Both farms are connected by horizontal bars. To absorb additional loads from new trusses, the branches of the outermost columns are reinforced with strip steel and the elements of their lattice, which interfere with the installation of trusses, are dismantled. Then I assemble and mount the spatial block (two two-plane trusses united by horizontal gratings), perform the project interface of the block with the outermost columns and mount a new lattice of all columns. of the middle column, it is required to give the vertical trusses of the spatial block a preliminary deflection close in magnitude to the calculated deflection from constant loads.To do this, each of the trusses is loaded in two middle nodes of the upper chord with loads (50 tons each) that provide the required deflection (1.4 cm at a calculated 1.29 cm). After that, the trusses are welded to the middle column, the weight is removed and its lower part is removed. For the duration of the work, the movement of all overhead cranes that transfer loads to the columns of the reconstructed section of the building must be stopped. In the second solution, instead of lattice trusses support beams are used, based on reinforced columns (Fig. 2, a). This reduces the consumption of materials and reduces the time of work. At the same time, the option of dismantling the lower parts of the columns with a special support frame under the crane beams and the upper parts of the columns is taken as the main one (Fig. 2, b). The support frame consists of five flat and one space studs to be installed on new foundations. On racks on either side of the existing columns, the main supporting beams are installed. The beams are interconnected by a system of horizontal ties along the upper and lower chords. Between the main supporting beams T, auxiliary beams are provided, to which the upper parts of the columns are attached using special tables. All loads from the roof and cranes are transferred to the supporting frame. The adopted option, compared with the first one, makes it possible to drastically reduce the construction time, reduce the mass of new metal structures by 230 tons, eliminate the work of dismantling and installing reinforced concrete coating and insulation with a soft roof on a site with an area of ​​about 2600 m2.

Fig.2. Strengthening of structures with an increase in the pitch of columns in existing workshops with the help of a - supporting beam device; b - devices of supporting frames; 1 - reinforced columns; 2 - supporting beam; 3 - dismantled part of the column; 4 - frame crossbar; 5 - frame stand: 6 - auxiliary beam; 7 - jacking beam

The sequence of technological operations for the transfer of loads from the roof to the supporting structures and the removal of the lower part of the columns is the same as in the first variant of the use of spatial trusses. Hanging of crane beams is carried out if it is necessary to strengthen the crane branches of the columns, reconstruct their heads or supporting parts of the crane beams, restore the design position, disturbed as a result of uneven settlement of the foundations of the columns, install the crane beams on a new high-altitude horizon. When hanging crane beams, the methods of lifting and squeezing are used with re-supporting on temporary rack supports; suspensions attached to columns, truss or truss trusses, as well as temporary mounting tables, etc. are used. Depending on the nature and degree of constraint of the installation area, the presence of lifting mechanisms, as well as the bearing capacity of roof structures, lifting of truss beams can be carried out: self-propelled jib cranes, overhead crane-beams, telphers, mounting masts and booms, chain hoists and winches, overhead cranes of higher tiers or specially re-equipped mounting beams installed on the roof of the workshop, etc. . Crane beams of the middle rows are lifted in blocks - two crane beams, ties, brake deck and rails. Crane beams are squeezed out using hydraulic jacks and temporary support devices, spatial A-shaped portals by tightening their supports (Fig. 3), as well as using special interchangeable equipment on a caterpillar boom crane (Fig. 4). Tubular or lattice racks, as well as spatial supports, are used as temporary support devices. When using racks, a support rack is installed on a specially prepared base (an independent foundation, a sleeper cage, a package of steel beams) using a winch and chain hoist and unfastened with braces in the upper and lower nodes. If the rack is installed on a specially arranged foundation, then the lower assembly is fastened with anchor bolts. Hydraulic jacks installed on the same base raise the rack until its upper node touches the crane beam and temporarily connect them. The crane beam junction is disconnected by the column and the adjacent crane beam and a further rise is made to the estimated height, while filling the resulting gap between the uprights and the base with linings. If a block of crane beams is lifted in the middle rows of the workshop, then the support post is installed along the longitudinal axis of the block, and its interface with the block is carried out using transverse thrust beams welded between two crane beams. It is also possible to use a stand equipped in the upper node of the transverse beam with struts, on which the lower chord of the suspended crane beam is supported.

Fig.3. Squeezing out crane beams with the help of a - hydraulic jacks; b - temporary supports; c - spatial A-shaped portal; 1 - column; 2 - crane beam; 3 - temporary support; 4 - stretch marks; 5 - hydraulic jacks; 6 - portal; 7 - clamping device

Fig.4. Special equipment for cranes for squeezing out crane beams 1 - caterpillar crane with interchangeable equipment; 1 - unloading support; 3 - jack; 4 - mounting platform; 5 - supplied temporary support; 6 - cargo chain hoist; 7 - crane beam

Rack supports are used mainly when the height to the bottom of the crane beam does not exceed 10 m. In other cases, as well as with a large mass of crane beams, it is more rational to use spatial supports with increased bearing capacity and spatial stability. The use of such supports, equipped with special working platforms, makes it possible to simply re-support the crane beams on the support with the help of transverse intermediate beams, which reduces the complexity and time of work. With large volumes of work on hanging crane beams and relatively low internal constraint of the reconstructed spans of the workshop, the spatial support can be made collapsible, movable or rearranged. The use of A-shaped spatial portals that combine the functions of temporary support and squeezing devices makes it possible to abandon the use of hydraulic jacks and simplify the process of re-supporting a suspended crane beam. The portal is a crossbar, at the ends of which there are two pairs of cheeks with holes and two pairs of posts, the upper ends of which are wound between the cheeks and hingedly connected to each other and to the crossbar. The lower ends of the uprights are equipped with ski-shaped bearing parts. Racks are connected in pairs with clamping devices. The portal is installed on a metal sheet or sections of channels, the surface of which can be lubricated to reduce friction forces between the base and the supports of the portal. The process of squeezing the beam consists of two main stages. At the first stage, a portal is installed; tightening the racks, bring the crossbar to contact with the bottom of the crane beam and temporarily connect them. At the second stage, the junction node is disconnected from the adjacent beam, the hanging beam is disconnected from the column and, by pulling the racks, the beam is squeezed to the calculated height. Jacks and temporary supports are installed only at the truss nodes. To prevent damage to the truss elements at the point of support, the nodes are reinforced, and in some cases, the design of the lattice is changed to create new nodes. The nodes of re-supporting roof trusses on temporary supports should be chosen in such a way that the signs of the design forces in the elements of the suspended truss do not change to the opposite.

Fig.5. Hanging roof trusses with the help of a - temporary racks; b - spatial supports; in - platforms arranged on crane beams; g - a platform arranged on a column; d - platforms arranged on an overhead crane; e - jacks installed on crane beams: 1 - temporary rack support; 2 - spatial support; 3 - hydraulic jacks DG-200; 4 - working platform: 5 - crane beam; 6 - farm; 7 - pumping station NSP-400

When using hydraulic jacks and temporary supports for hanging roof trusses, the sequence of technological operations is similar to those described above for crane beams. Some features are characteristic of the methods of arranging the supporting parts of trusses and racks. One of the simplest options for rebuilding the upper node of the truss truss is as follows. Two corners are welded to the kerchief of the upper truss node on both sides, to which the support beam is attached with bolts. The length of the beam is determined in such a way that its ends extend beyond the edge of the lower chord of the truss by 250-300 mm. Holes are made in the lower part of the beam for bolting with a temporary support. Loops are welded to the beam for fixing roller blocks in them, which serve for reeving winch ropes that raise temporary supports. With this solution, the length of the main shaft of the temporary support is 80-100 mm less than the distance from the upper mark of the support installation base to the lower chord of the truss truss. The upper part of the support is a fork-shaped head formed by two segments of channels welded to the main shaft so that the distance between them is 50-100 mm greater than the width of the lower chord of the truss. The upper part of the channels is structurally solved in such a way that their mating with the support beam is ensured. The need to raise trusses by 55-200 mm with the help of hydraulic jacks and platforms arranged on crane beams can be caused by uneven foundation settlements, which leads to disruption of the normal operation of overhead cranes and building structures. When developing a PPR, it is necessary to determine the force required to squeeze the farm; in most cases, it is possible to provide the possibility of using existing crane beams as a support base. Each truss can be lifted with two DG-200 jacks powered by one NSP-400 pumping station. The forces from the jacks to the upper belt of the trusses are transmitted through temporary racks. The production site is divided into two captures. Within each, before the start of lifting the trusses, temporary racks are mounted, jacks with pumping stations are installed and the zero rods of the upper chords of the trusses are dismantled. The truss with the greatest deformation is lifted first within the grip, then, as it is leveled, the rest are squeezed out. The rise is done in steps. Every 20 mm, the lifting is stopped and the roof structure is inspected, paying special attention to the condition of the braces and truss belts. The lifting of trusses within the grip, including preparatory work, is performed by a team of 8 installers in 10 hours. A-shaped portals are used mainly in cases where the truss truss is supported in the lower node. Such a solution does not require the rearrangement of the lower truss node, but only the strengthening of individual elements of the truss lattice. With a high internal constraint of the reconstructed spans, as well as with large amounts of work on hanging roof trusses, it is advisable to use mounting mobile roof portals for these purposes. The portal is a lattice spatial structure of the gantry type, the span of the office is equal to two steps of truss trusses. The portal moves with the help of winches along the rail tracks laid on the roof of the workshop. The portal is equipped with a belt-type hoist, including a gyro jack with a pumping station, a jacking beam, tape traction and a support beam attached to the lower section of the rods. Before hanging the trusses, the coating area is released from the loads acting on the roof and the set of works provided for by the project is carried out to strengthen the existing structures and ensure the spatial stability of the frames for the period of work, and also fix the support beam of the belt lift to the truss. At the same time, sections of the under-portal track are laid, a winch is installed, the portal is lifted to the roof with a jib crane and installed on the track. Starting work, the portal is rolled into the working position with the help of a winch and fixed with stops fixed to the rails. Mark the places for the passage of rods and punch holes in the roofing. The belt lift rods are lowered through the holes, they are attached to the installed support beam, and by turning on the hydraulic jack, the gap between it and the overjack beam is selected. The truss junction with the column is disconnected, lifting to a predetermined height and re-supporting the rods or the over-jack beam on the superstructure of the portal are performed. The rise must be carried out in steps of 20-30 mm, constantly monitoring the condition of the coating elements.

The diversity and specificity of the objective situations of reconstruction makes it necessary to search for individual technological solutions for the production of dismantling and installation works for each specific case, with the task of minimizing the duration of the shutdown of the reconstructed production.

With all methods of dismantling buildings and structures, measures must be taken to reduce the formation of dust. To this end, dusty materials are moistened. Open dropping of materials from a height is not allowed. Descent of materials for loading should be carried out in containers or through temporary garbage chutes

The main technological requirements for the installation of structures in the conditions of reconstruction are as follows: the greatest readiness of structural elements supplied to the installation site; limiting enlargement of mounting elements beyond the area of ​​their installation in the design position, taking into account the possibility of transportation and installation by crane and craneless methods; the use of auxiliary devices for the passage of cranes, the assembly and sliding of individual parts of structures, the strengthening of individual structures and the suspension of existing parts of buildings; use for installation work in agreement with the customer technological overhead cranes and other handling equipment. The structures of temporary fences separating the installation area from the existing production should be inventory and ensure ease of rearrangement.

Dismantling of structures and replacement of structural elements. Dismantling of blast furnaces during their reconstruction is carried out using tower and tower-jib cranes, chain hoists and mounting beams. Cranes are installed so that the largest number of elements can be dismantled from one parking lot. The casing of the blast furnace is dismantled in tiers. The work begins with dismantling the lining from top to bottom within the tier, while using decks that protect the lining elements from falling. The metal casing is dismantled by drawers or cut into separate elements.

The pipelines are dismantled together with the lining. The dismantled structures are divided into elements by flame cutting with preliminary cleaning of the cutting areas from the lining.

Tanks and gas holders are dismantled by drawers or dismemberment into separate elements, having previously taken measures to prevent loss of stability by installing temporary supports and internal diaphragms near the dismemberment sites. The dismantling of vertical tanks begins with the coating. Before removing the roof, the walls of the tank are moored. The coating having a central support is dismantled by diametrically located sectors. The pavement, which does not have a central support, is dismantled in one element or sectors with the installation of a temporary support. The walls of the tanks are dismantled in tiers, from top to bottom. The braces are rearranged as they are dismantled to ensure the stability of the remaining part of the tank. The dismantling of floating roof tank structures starts from the wall. The roof is removed last.

Gas holders are dismantled in the following sequence: bell, telescope, tank. The bell is dismantled as a tank without a central support. Before dismantling the cover of the bell, the weights must be removed.

Galleries are dismantled in the direction from the movable support to the fixed one. Otherwise, temporary links are placed to ensure the stability of the gallery. The structure in the span of the gallery is dismantled in the following order: roofing, wall fencing, beams and ties along the upper chord (except for elements that ensure the stability of trusses), roof structures, beams and ties along the lower chord and the remaining elements along the upper chord, trusses. When dismantling farms, they must be uncoupled. If it is impossible to remove the entire trusses, temporary planar or spatial supports should be installed. In places where the truss is supported on temporary supports, in order to avoid loss of stability, it is fixed on the supports with struts.

The dismantling of masts, towers and pipes is carried out in the reverse order of installation. In this case, self-elevating, attached and self-propelled tower-jib cranes are used. Helicopters are used for dismantling the upper part, and the specified assembly cranes are used for the lower part. Dismantling is carried out in tiers with the obligatory installation of temporary guys on the entire support tier. In the presence of support insulators, the latter are replaced by a temporary rigid support.

Reinforced concrete trusses and beams are dismantled using cranes. The structure is unfastened and a temporary support is installed under it. Cut down the concrete of monolithic joint with the column. The final separation of the structure is carried out after fixing the slings, which are taken on the crane hook. The dismantled structure is immediately loaded onto transport and taken out of the assembly area. It is not allowed to leave farms in a vertical position on temporary supports and fastenings.

The dismantling of reinforced concrete crane beams is carried out with the help of cranes moving inside the workshop, as well as winches and pulley blocks mounted on trusses. The final separation of the structure is carried out after fixing the slings, which are taken on the hook of the mounting tool.

To replace the reinforced concrete slabs of the coating, a layer of roofing material is cut along the perimeter of the slabs, a screed along the insulation and a monolithic sealing of the seams are cut out, the places for welding embedded parts are cleared, the welded embedded parts are cut off by flame cutting, holes are punched for slinging, the released slabs are removed along with the remaining insulation and roofing and laying new tiles.

Slinging is carried out through punched holes or in a girth using slings or special traverses suspended on a crane hook.

The material from the cut insulation and pieces of the roof are immersed in a container. Small roofing slabs and elements of steel stamped roofing sheets are placed in packages of 4-5 pieces. and removed with cranes.

When dismantling roofing slabs in existing workshops without stopping production, work is carried out in separate areas, while dismantling must be combined with the installation of new structures and laying the roof. Cranes are located on the outside of the building or on its surface.

To ensure the safety of those working in the building, a solid flooring of shields is laid along the lower chords of farms. With a truss step of more than 6 m, light metal beams are used, along which shields are laid. Sheets of steel or asbestos are laid on the shields to protect against fire during welding and cutting structures. Awnings made of waterproof material are assembled over the work area, which are gradually moved along the front of the work.

Work on the replacement of coatings above the existing workshops should be planned for the warm season.

The replacement of columns inside the workshop is carried out when it becomes necessary to install new equipment, lay underground utilities while maintaining the coating structures unchanged.

Rice. 10.34. Replacing columns with hanging roof structures:

a - by the method of rotation around the hinge; b - winches; V - installation of temporary supports; 1 - dismantled column; 2 - temporary support; 3 - chain hoist; 4 - support table; 5 - swivel joint; 6 - safety rope; 7 - long-span crane beam; 8 - pull rope; 9 - sleeper cages;

10 - crossbar for fastening a cargo chain hoist; 11 - outlet block; 12 - hydraulic jack

The dismantling of columns is preceded by a set of preparatory works: foundations for temporary supports, reinforcement of roof truss elements, removal of crane beams resting on the column being dismantled, cleaning of the roof to reduce the load on temporary supports. With the help of winches with a lifting capacity of 3 tons, they lift and install temporary tubular supports. The length of the supports is determined so that the lower part enters the guides of the supporting foundation by 150-170 mm, and the upper part does not reach the lower belt of the truss truss by 80-100 mm. The upper part of the support is attached to the truss support table (Fig. 10.34).

Oxy-fuel cutting is used to disconnect the supporting nodes of the truss trusses. Particular care is required when cutting welds in the area of ​​the supporting ribs of truss trusses. The transfer of the load to each temporary support, by simultaneously jacking them up, is carried out using hydraulic jacks synchronously operating from one pumping station. The rise is carried out until a gap of 3-5 mm is formed between the supporting part of the truss truss and the column.

The dismantling of columns is carried out with the help of a swivel joint and two chain hoists, one fixed to the upper part, the other - below the center of gravity of the column. The column is destroyed at the hinge installation site or disconnected from the foundation. The column is lowered with a winch with a chain hoist attached to the upper part, another chain hoist comes into operation only after the column is tilted by 30 °. The latter is laid on linings and taken out of the dismantling area.

The installation of a new column begins with the preparation of the foundation and the installation of a swivel hinge on it, which is fastened with anchor bolts into holes filled with epoxy glue. The column is fed to the installation site, its end is inserted into the holder of the support hinge and fixed in it. Verify the position of the column in the plan and check the dimensions. The installation of the column is carried out using the “falling” boom method, using an electric winch and a mast. The column installed in the design position is fixed to the foundation, then the truss truss assembly is planted on the column head and fixed.

The dismantling of metal columns with a crane is carried out after the destruction of the concrete, the base of the metal column is fixed with the foundation using jackhammers. Then the column is taken on a crane hook and the anchor bolts are cut off. Reinforced concrete columns are allowed to be cut down above the level of the foundation. In this case, after removing all loads from the column, it is hemmed so that all reinforcing bars are exposed for cutting, but at the same time, part of the concrete remains uncut, constituting 30-35% of the cross-sectional area. After taking the column on the hook of the crane, the remaining part of the concrete is hemmed and the reinforcing bars are cut.

The replacement of wall enclosing structures is carried out in separate sections, first removing a row of panels adjacent to the roof or immediately in height from top to bottom. First, with jackhammers, a monolithic seam along the panel contour is destroyed, holes are punched for their slinging, the seams of the plates are cleaned of mortar at the attachment points. The panels are slinged with a special device of two brackets and fixing pins, which can be passed through the punched holes. Before cutting the fastening elements, the panels are hooked onto a crane hook. The workplace for installers is provided with mobile towers, cradles.

Installation of membrane coatings. Membrane coatings make it possible to carry out construction and installation work during the reconstruction of an enterprise without stopping production and creating a pavilion-type building instead of cramped spans. This is how the reconstruction of workshop No. 2 of the Kompressor plant was carried out. The workshop was a six-bay building with spans 13.5 m long. The columns and crane beams were made of monolithic reinforced concrete, the covering was made of wooden trusses and wooden girders with triangular lanterns (Fig. 10.35 ). By the beginning of the reconstruction, the workshop was lined with buildings on three sides. Membrane coating is an external load-bearing contour on columns, a membrane from a sheet 4 mm thick is stretched in the contour. The bearing circuit is designed from a pipe with a diameter of 630 mm and a wall thickness of 14 mm. The contour rests on the walls of buildings by means of columns. The circuit weighing 62 tons was mounted with enlarged elements using an SKG-40 crane. Along axis 14, the contour elements were pushed in the direction from axis A to axis P. To create additional rigidity, concrete was injected into the contour on fine aggregate.

The membrane was supplied in rolls for a span of 81 m with a small margin, a roll width of 6 m, a diameter of 3 m, and a weight of 15 tons. The total mass of the membrane was 168 tons.

Preparation for installation began with the construction of scaffolds, on which the membrane elements were deployed and connected.

In the presence of an existing workshop, its roof was used as a working horizon for paving.

Rice. 10.35 Membrane cover installation diagram

during the reconstruction of workshop No. 2 of the Kompressor plant, Moscow:

a - plan of the workshop (existing buildings are shaded); b - cross section with the location of the mounting

fixtures; 1 - drum with a roll; 2 - membrane strip; 3 - sling for sliding the strip;

4 - scaffold flooring; 5 - traction cable of the chain hoist; 6,7 - outlet blocks; 8 - winch; 9 - wooden trusses of the existing workshop; 10 - trapezoidal scaffold supports

During the reconstruction of shop No. 2, the assembly load (membrane - 169 tons and scaffolding - 67 tons) was transferred to the existing wooden trusses through trapezoidal elements. The system of mounted scaffolds was subjected to examination, after which the installation of the membrane coating was started.

Each roll of the membrane was unrolled on a special drum located at the level of the shop floor. The sliding of the membrane strips was carried out by a winch with a lifting capacity of 5 tons (Fig. 10.35. b)- The strips were laid from one edge of the coating to the other (from axis 14 to axis 3). Fastening to the contour was carried out by welding with a continuous seam, and between themselves - with electric rivets with a step of 150 mm.

A very important operation was the uncircling of the membrane. The order of circling was provided by the project. The lowering of the scaffolds was carried out by extending the supports with a change in the length of the base of the trapezoid. In one step of extending the supports, the membrane could be lowered by 555 mm. To ensure uniform loading of the scaffold, the supports were lowered in the direction from the center of the membrane to the contour. After circling, the membrane sagged in the middle of the span by 2 m. An ordinary lightweight warm roof was laid over the metal membrane. A total of 537 tons of structures were installed.

The interior of the workshop under the membrane coating was subjected to a phased dismantling with the installation of a new type of equipment. The installation of the membrane coating was carried out by one team in one shift. The total labor costs amounted to 1534 man/days. The output per one man-day worked was 350 kg, excluding installation and dismantling. Despite a significant reduction in metal consumption per 1 m 2 of coating, the production of membrane coatings during installation is close to the industry average.

One of the successful examples of solving the issues of organization and technology of dismantling works is the dismantling of the span of the wheel-rolling shop of the pipe-rolling plant, carried out during its reconstruction (Fig. 10.36)

The working draft provided for the dismantling of the structures of part of the spans I-D and Zh-D in axes 8-21. The area of ​​the dismantled section of the workshop was 3580 m 2, the mass of dismantled structures was 300 tons, including girders - 91, lantern trusses - 1.6, roof trusses - 70, crane beams - 29, column ties - 4.4, columns - 83 tons

The dismantled part of the wheel-rolling shop was mated on three sides with the saved spans. To ensure their normal operation in the dismantled part of the workshop (along row D), it was planned to mount a temporary enclosing wall.

Prior to the start of the dismantling of the building, it was planned to carry out all the preparatory work to ensure the safety of the dismantling - work: arrange passages and driveways, close the movement of technological factory transport along the existing railway track, install barriers. Dismantle existing power lines and communications in the area of ​​dismantling, put up warning signs, organize a fire station, cover with metal sheets the technological devices and equipment operating in the area of ​​dismantling.

To dismantle the structures, it was supposed to use the MGK-25 crawler crane with an arrow of 17.5 and a beak of 8 m; for loading dismantled structures onto a railway platform, an MKA-10M truck crane; for the removal of structures outside the workshop four four-axle platforms.

Limited access to the dismantled part of the workshop due to its interface with the existing spans, as well as the presence in the dismantling zone of the existing technological systems of the workshop (exga-uster; ducts, chimney) predetermined the following sequence of work: dismantling of the crane beam and runs along trusses and lanterns , lanterns in axes 11-11a of span I-D; dismantling of slabs, purlins, lanterns and roof trusses from axis 11 to axis 8 of the span I-D; dismantling of crane beams and columns along the I row from axis 8 to axis 11; dismantling of runs along trusses and lanterns, lanterns in axes 11a-13, roof trusses in axes 11-12a, crane beams and columns in axes 11a-12 of row I; dismantling of girders, lanterns and roof trusses from axis 13 to axis 16; dismantling of crane girders and columns along row I of axis 13 to axis 16; dismantling of crane beams of row D from axis 21 to axis 16

Fig.10.36 Scheme of organization of work on dismantling the structures of the existing span