Column installation... Reinforced concrete columns, depending on their mass and length, supply conditions, characteristics of the cranes, are lifted by translational movement of the column by the crane, by turning the column around the base and by translating the crane, by turning the column and crane boom. Heavy and tall columns are lifted by moving the lower end on a trolley or by turning around the base on a steel shoe.
For the installation of light columns, friction grips are used (Fig. 6.15). After the column has been installed, the grab is pulled down by gravity and released.
It is also possible to sling the column "in the girth" with an ordinary universal sling. Heavy columns are gripped with double-strap traverses, which are hooked into the mounting eyes above the center of gravity.
Typical prefabricated reinforced concrete columns of one-story industrial buildings weighing 1.8. 26.4 t and a height of 3.8. 19.35 m, mounted in glass-type foundations using wedge inserts TsNIIOMTP (Figure 6.23, b).
Before installing the columns in the foundations, it is necessary: to accept the foundations according to the act (with the attachment of the executive scheme); close the glasses of the foundations and fill the sinuses of the foundations; deliver to the installation area the necessary assembly tools, as well as accessories and tools, in accordance with the standard set; mark the center lines on the top edges of the foundations and the side edges of the columns.
The "mounting horizon" is being set up. With the help of the level, the “mounting horizon” mark is placed inside the foundation glasses, i.e. the bottom of the column to be installed. According to these marks, the bottom of the foundation glass is poured (mortar of grade M50, fine-grained concrete of class B7.5). For heavy columns, the "mounting horizon" is arranged from a package of reinforced cement gaskets, because Such columns during installation "squeeze out" partly the gravy, which lowers the design elevation of the column (Fig. 6.25, a). Pads 100 × 100 mm in size, 10, 20, 30 mm thick made of grade 100 solution are reinforced with a mesh with cells 10>; 10 mm made of steel wire 1.0 mm in diameter.
The slinging of the columns is carried out by means of mounting loops or a special rod passed into the hole of the column. In the absence of mounting loops or special holes, the columns are strapped with a friction grip or a noose loop at the places indicated by the manufacturer. To ensure the safety of the rope, steel linings are installed under the ribs of the columns at the points of abutment of the rope.
Temporary fastening and alignment of the columns is carried out with wooden or steel wedges, as well as with wedge inserts. They allow you to move the bottom of the column "left-right" and "forward-backward". The verticality of the column is regulated by an erection crane jib from the top of the column.
The alignment of the column axes and the alignment axes on the foundation is controlled along two mutually perpendicular axes. The verticality of the columns is checked using two theodolites or a theodolite and a plumb line along two alignment axes. In this case, one theodolite must be installed along the mounting axis and the installation of the columns is carried out in the direction "towards itself" (to the theodolite). The second theodolite is transverse and is rearranged for each column. The elevations of the support sites for crane beams and truss structures, as well as the bottom of the foundation glasses, are controlled by the method of geometric leveling.
The installed columns are unstitched only after they are fastened in the foundation glasses with wooden or steel wedges from four sides.
Columns with a height of more than 12.0 m must be additionally fastened in a plane of lower rigidity with braces made of steel ropes.
Execution of a working joint. It should be remembered that the reinforced concrete column transmits the design vertical forces to the foundation, not only by the end (bottom surface) "pushing" the foundation, but also by the side faces connected to the walls of the foundation glass with monolithic concrete of class B15. IN 20.
The joint cavity is blown with compressed air from a mobile compressor and wetted (the walls of the nozzle and the lower part of the column). The cavity is filled with a rigid concrete mixture and compacted with a slot vibrator (a deep vibrator with a steel bar nozzle with a diameter of 15.20.0 mm). Within three hours, the movement of heavy vehicles (cranes, tractors, loaded vehicles, etc.) is not allowed closer than 20.0 m from the monolithic joints.
In the design places (in the middle of the temperature block), to ensure the longitudinal stability of the building, vertical ties are installed between the columns of the frame. Vertical braces are made of rolled steel (angles or channels): cross, with a column pitch of 6.0 m: portal, with a column pitch of 12.0 m. After installation, the following structures can be installed - crane beams or trusses.
Installation of crane beams... Reinforced concrete crane beams are T-shaped elements with a length of 6.0 m with a height of 800 mm and a mass of up to 3.0 t and a length of 12.0 m with a height of 1400 mm and a mass of up to 8.0 t, which are supported on the column consoles.
On the support consoles of the columns, the risks of the alignment axes of the crane beams are applied. On the beams themselves, central axial marks are applied on the supporting parts. The beams are strapped with a two-branch sling "in the girth" (with pads for the rope). Beams 12.0 m long are lifted using a traverse (Fig. 6.26).
The "mounting horizon" along the supporting consoles of the columns is arranged as follows. Having determined the highest mark according to the scheme, all other anchor points, the level of which differs by more than 2.0 mm, are raised using a package of steel spacers with a thickness of 1.0 mm.
The beams installed on the console of the columns are temporarily fixed with a conductor, with the help of which the ends of the beam are moved when it is aligned in the plan. Alignment of beams is carried out within the temperature block or span using geodetic instruments: in height - by the method of geometric leveling; in the plan - by the method of lateral leveling using a theodolite or along a plumb line with steel wire stretched 0.8-1.0 m above the level of the crane beams along the axis of the crane runway and fixed on brackets welded to the column.
The distances between the axes of the installed beams are checked with a comparative tape measure with a two-fold displacement of the measuring drive, correcting for tape sag and temperature. The permissible average error during geodetic control should not exceed 20% of the permissible deviation for the controlled size.
When installing beams with crane rails already installed on them, the distance between the heads of the crane rails is measured.
Installation of the tent... When installing single-storey industrial buildings with mobile jib cranes, it is not possible to lay cover slabs on the trusses mounted throughout the building during the lateral driving of the crane. Therefore, a complex installation of a "tent" on a cell (column pitch) is carried out: roof trusses, roof trusses, light-aeration lantern trusses, roof slabs.
The "tent assembly" flow is performed by a mobile crane with a lifting capacity of 25-63 tons with appropriate assembly equipment, which runs along the span axis and performs "pull-on" assembly. With a spacing of the bearing columns of 6 m, cranes with ordinary booms or jib booms are used; with a column pitch of 12 m, installation is carried out with jib booms or tower boom equipment.
When installing the tent, the first truss installed in the design position is fixed with three pairs of braces (in the center and but at the edges of the truss), the second and subsequent trusses are fastened to the previous one using inventory spacers of a fixed length (6 or 12 m) (Fig. 6.25).
On the heads of the columns, risks of the design axes are applied. Central risks are applied to the supporting parts of the trusses. A railing is arranged along the top of the farm. Guys from a hemp rope of the required length are attached to the ends of the truss to turn and guide the supporting parts of the truss to the column head. In the center of the upper chord, an assembly spacer with a length of 6.0 or 12.0 m (in column spacing) is attached.
The “mounting horizon” in this case does not suit, because the accumulation of errors in height has ceased, and the correction of errors in the elevations of the top of the columns is not required.
Roof beams and trusses with a span of more than 12.0 m are lifted with traverses, the length of which depends on the length of the structure being lifted.
The slinging of trusses, depending on the span, is carried out in two, three or four points. The farm is captured at the nodes of the upper belt.
The first truss truss (without a spacer) is lifted with a traverse of the appropriate length and is aimed at the column heads. The alignment of the supporting parts of the truss (alignment of the axial marks) is carried out "by weight". Correcting the situation - lifting with a crane and re-aiming.
Temporary fastening of the first truss is carried out by three pairs of wire rope braces fixed to the ground by anchors (anchors) (Fig. 6.27). The vertical alignment of the farm is carried out with a plumb line. A welded assembly joint is made on the support parts.
The second truss truss and all subsequent trusses are similarly placed on the column heads and fixed with a mounting spacer to the first truss (to the previous one). Mounting joints are made on the supports.
Next, the covering slabs are mounted on the cell (two trusses installed on the columns). Lifting a slab with a length of 6.0 m is carried out with a four-leg sling, with a length of 12.0 m, various traverses are used. After installation, the plates are welded at three points (one point is inaccessible, Fig. 6.27, d) immediately with a working seam, because the connection points are sequentially closed by subsequent plates.
Installation of external wall fences... After the end of the installation of the building frame or part of it, the wall panels begin to be mounted. In most cases, the wall enclosure is installed in an independent flow after the installation of the building frame and coating is completed.
Design solutions regulate the layout of the outer and end walls, as well as the layout of the panels in the upper part of the walls (with parapets and cornices). Methods for attaching panels to columns, as well as filling joints between panels, are shown in Fig. 6.25.
Before starting the installation, the wall panels must be stored at the working parking areas in the area of the assembly crane. In this case, there can be three options: for buildings of low height, the cassette is located between the assembly crane and the wall to be mounted (the volume of the cassette provides a sufficient number of panels for the wall to be installed over the entire height of the building); the assembly crane is located between the cassette and the wall to be mounted (the volume of the cassette provides the wall device for the entire height of the building); if the wall device is provided with two cassettes, an assembly crane is positioned between these cassettes.
If the height of the wall consists of more than 12 panels, installation is carried out in two crane passes. In this case, the installers verify and fix the panels to be installed from the working platforms located on the inside of the building. If it is possible to travel inside the building, it is advisable to use two car-based lifts as workplaces for installers. In the absence of lifts, various scaffolds and climbing cradles can be used as working platforms.
Progressive technology for the installation of external walls of single-storey industrial buildings is based on the use of specialized tower-boom equipment developed for the RDK-25 boom cranes; E-10011D; E-1254, as well as for tower cranes of the BKSM-3-5-8 type (Fig. 6.28).
The main technological features of the use of specialized equipment for jib cranes are: combining the functions of a lifting crane with an assembly site; the ability to move the mounting platform up and down the tower, as well as horizontally - from the tower to the wall and back; placement of wall panels in cassettes installed between the crane and the wall to be mounted; the width of the installation area along the perimeter of the building when the crane is operating with specialized equipment is about 8.5 m.
The slewing part of the jib cranes can rotate with the lower position of the mounting platform at the minimum overhang. In other positions of the mounting platform, the slewing part of the crane is automatically blocked.
Progressive technology of external wall fencing installation ensures cost savings by 1.5-2 times.
The wall panel is lifted with a crane at the maximum distance of the mounting platform from the wall. After the panel is fed to the installation site, the mounting platform, together with the installers, is fed close to the wall (the supply stops automatically after the restraints stop in the columns).
The on-site installers ensure the guidance and installation of the panel in the design position, its alignment, temporary and final fastening by means of electric welding of embedded parts.
Sealing of horizontal and vertical joints is carried out immediately, simultaneously with installation. When installing wall panels with a conventional jib crane without the described special equipment, the seams are sealed into a separate flow and carried out together with the “finishing” flow. In this case, work is carried out from external adjustable, mobile and self-propelled scaffolding; hanging cradles.
For the injection of sealing mastics and solutions into the seam cavity, hydraulic, pneumatic and mechanical blowers, injectors, and mortar syringes are used.
Simultaneously with the installation of wall panels, steel elements of light openings (imposts, bindings) are installed.
Installation of reinforced concrete structures of one-story industrial buildings
Installation of reinforced concrete structures of one-story industrial buildings. Installation of columns. Reinforced concrete columns, depending on their weight and length, supply conditions, crane characteristics raise
Methods and technology for assembling elements of frame buildings depend on their design solutions, number of storeys and available installation equipment.
The frames of multi-storey buildings with two-storey cut columns are recommended to be mounted using group or articulated conductors. This provides a forced fixation of the columns in the design position during their installation, thereby reducing the amount of alignment work. The rest of the frame elements are mounted in a free method.
It is recommended to mount the frames of one-story and low-rise industrial and administrative buildings using a limited-free method using single or group conductors.
The most important rule that must be followed for any organization and installation method is to ensure the stability of the mounted structures. In this regard, any installed structure cannot be freed from the crane hook until it is securely fastened. The sequence of installation of the frame elements should be such as to ensure the rigidity and geometric invariability of the mounted part of it.
Taking into account this requirement, when erecting the frame of one-story industrial and other buildings, it is recommended to observe the following sequence: the first on each site (capture) are installed structures, between which the links are located (vertical, horizontal, etc.). Each next structural element is attached to the previously installed connecting elements provided for by the project: crossbars, ties or temporary struts and ties.
Prefabricated elements of multi-storey buildings in each grip (section) are assembled in the following sequence. First, the columns and crossbars of the frame are installed in the stiffening cell or starting from the end of the building (section) along its entire width and on all floors of the tier. After verifying the position of the columns and girders and their fastening, ties or tie panels and spacer slabs of floors between the columns are installed. Then, the internal panels of the staircase, staircases and marches, external wall panels of the staircase, ventilation blocks, sanitary cabins, wall panels of external walls and partitions are mounted. After assembling the elements of one section and securing them by welding, the crane is moved to the next section, and on the assembled section, welding work is completed, the joints are monolithic, and the floor slabs are mounted. Installation work is performed in the same sequence in all subsequent sections of the tier.
The installation of the second tier is started only after the alignment of the installed structures, welding of all erection joints of the first tier and control of the correct installation of structures and the breakdown of axes and marks for the subsequent installation of structures with geodetic instruments.
Before starting the installation of structures on each tier, which can include two or three floors (depending on the cutting of the columns along the height of the building), mark the main alignment axes of the building on the ceiling or column heads, determine the mounting horizon, mark the axial and other installation risks. Axis risks are measured each time from the main alignment axes and the relative position of adjacent axes is checked.
The most common multi-storey residential, public and industrial frame buildings are with frame cells 6 x 6 and 9 x 9 m, other spans are possible, for example, 12 m and intermediate ones. Floor height 3; 3.3; 3.6; 7.2 m. The width of buildings is usually 12; eighteen; 24 and 36 m. The upper floors can have halls up to 10.8 m high, with a span over the entire width of the building or part of it, including with or without overhead cranes. The length of the building is a multiple of the cell parameter.
For supporting frames, columns are used on one, two, three floors. Depending on the space-planning solutions, buildings are built with a transverse or longitudinal arrangement of crossbars, along which floor slabs are laid, respectively, in the longitudinal or transverse direction.
Building frame assembly is an interconnected process of installing columns, girders, stiffening diaphragms, tie and interfloor floor slabs. The elements are installed in such a sequence that ensures the rigidity and spatial immutability of the frame. The sequence of installation in each specific case is determined by the project for the production of work and a set of installation equipment, which will be used for the installation and alignment of structures: individual (single) or group fixtures.
Installation using individual means of assembly equipment.
In construction, individual means of assembly equipment are most often used, with the help of which structures are verified and temporarily fixed. The kits of individual assembly equipment for the installation of multi-storey frames include (see the diagram below, pos. A ... c): wedges and inserts, support beams, anchor devices, clamps, struts and horizontal struts, conductors. In contrast to group individual means are more versatile and easy to use (Fig. 1).
Rice. 1 - Diagrams of installation of multi-storey columns using a set of individual means of assembly equipment: a - the location of the columns and devices, b - securing the column with struts, c - a clamp for securing the struts to the column; 1 - foundation glass, 2 - inventory beam, 3 - column, 4 - clamp, 5 - brace, 6 - brace hitch, 7 - wedges, 8 - anchor device, 9 - crimping rope
Wedges and wedge liners are used for aligning and securing columns in foundation glasses.
The support beams consist of two channels connected by strips and have loops in the upper part for attaching struts, and in the lower part - end stops for fixing to the foundation glasses (see the diagram above, pos. A, b).
Anchoring devices 8 represent a U-shaped frame with holes in the upper part through which a gripping hook, which is moved by means of a tension nut, passes.
The clamp (see the diagram above, pos. C) for attaching the brace to the column is made in the form of an angle stop, which is fixed to the column using a rope with a tensioner.
The struts 5 consist of telescopically connected pipes with tensioning towheads 6 and gripping devices at the ends for securing to the hinges or lugs of the clamp and the hinges of the supporting beams or other structures.
Conductors are designed for temporary fixing and alignment of columns, which are joined in height with the heads of previously installed columns.
The columns of the first erection tier are installed using the same methods as in the erection of one-story buildings. However, in this case, struts and struts are installed that hold the columns in such a way that they do not interfere with the laying of girders and tie plates between the columns. Before the installation of the columns, the support beams 2 are laid on the grip (see the diagram above) and fastened to the hinges of the foundations using anchor devices. Support beams are not laid in those places where frame stiffness diaphragms are installed.
A clamp 4 is put on the mounted column in the warehouse and two braces 5 are hung on it, after which the column is strapped and lifted with a crane. The column supplied for installation is installed in the foundation glass and temporarily secured with the help of wedge inserts (wedges) 7 and two struts 5. After that, the column is strapped and adjusted. The column is installed in a vertical position using theodolites along two axes. As the installation progresses, the columns are embedded in the foundation glasses. The braces are removed from the columns after the frame has been unfastened with crossbars and slabs at the level of the two lower floors.
Crossbars are mounted after the columns (see diagram below, pos. A ... c). Before installation, the crossbars are cleaned, the reinforcement outlets are straightened and the embedded parts and the crossbars are dry supported on the column consoles. On each structural cell of the building, first the lower and then the upper crossbars are mounted. The workplace of the installers is at the inventory sites.
The works are performed in the following sequence. A third-class installer raises the crossbar and gives a command to the crane driver to lift. The driver moves the deadbolt to the installation site with a crane. Assembler of the 5th grade supervises the work of the crane. Assemblers of the 4th and 3rd categories, being on the adjustable platform-platforms, take the crossbar, put it on the shelves and check it.
In the transverse direction, the crossbars are installed in the design position, aligning their axes (outlets of the upper reinforcement) with the axes (outlets of reinforcement) of the columns, in the longitudinal direction - observing equal areas of support of the ends of the crossbar on the console of the columns (the difference between the areas of support of the ends of the crossbar on the console should not exceed ± 5 mm).
After aligning the crossbars, their supporting embedded parts are tack-welded to the embedded parts of the column consoles and the crossbar is unstopped (Fig. 2).
Rice. 2 - Installation of the girder: a - applying axial marks on the column, b - installing the girder, c - straightening the girder during alignment
After making sure that the columns and girders in the mounted cell are in the design position, the installers finally fix the girders with a bathtub by welding the outlets of reinforcement, welding of embedded parts, embedding the joints (after the completion of the welding certificate). Then the frame stiffness diaphragms are mounted (see diagram below, pos. A, b) with a shelf that replaces the crossbar (Fig. 3).
Rice. 3 - Installation of internal walls - stiffness diaphragms - in a frame building: a - installation, b - temporary fixing; 1 - brace, 2 - diaphragm with a shelf that replaces the crossbar, 3 - universal sling, 4 - adjustable clamp with a stand
For temporary fastening and alignment of diaphragms, adjustable clamps are used 4. Stiffening panels of the frame without a shelf replacing the crossbar are mounted before the crossbar is installed in this span. At the same time, instead of temporary fastenings of the frame at the installation site of the diaphragm, equivalent fastenings are placed on the other side of the column, for example, horizontal braces-spacers. The organization of the workplace and the sequence of operations are shown in the diagram below, pos. a, b.
Depending on the degree of enlargement, the following methods of installation of structures are used: by structural elements or their parts; linear, flat or spatial blocks; structural and technological blocks, consisting of building (usually steel) structures and technological equipment built into them; structures as a whole (power line supports, steel chimneys, etc.). In agricultural construction, assembly with structural elements is most common. When installing in blocks, the structures are enlarged before they are installed in the design position. Thanks to this, the number of lifts and the complexity of climbing work is reduced, the number of mounting elements and joints is reduced, and the manufacturability and reliability of the enlarged structure is increased.
According to the adopted sequence of installation of the structure in the span of one-story or on the floor of multi-storey buildings, differentiated (separate), complex (concentrated) and combined (mixed) installation methods are distinguished.
With a differentiated method, within the span or floor, structures are installed in separate mounting kits (tiers). So, in one-story agricultural buildings with a post-and-beam frame, firstly, the foundations are mounted, then the columns, and after the monolithing of the joints - beams (or trusses), covering slabs, wall panels. This method ensures the rhythmic operation of the crane during the installation of the same type of structures using permanent equipment, which contributes to an increase in labor productivity. For structures that differ significantly in their weight, several cranes are used, which makes it possible to more efficiently use their lifting capacity. However, the total number of penetrations and parking of erection cranes with this method increases, the start of post-erection works is delayed. The differentiated method is used when using mobile cranes for the installation of reinforced concrete, metal and wooden structures.
With the integrated method, all structures are installed within one cell of the building, verified and fixed. The number of movements and stops of the crane is reduced, the start of post-assembly work is accelerated, however, the use of the lifting capacity of the assembly cranes deteriorates in the case of a significant difference in mass of structures. It is advisable to apply the complex method when installing one-story buildings of a heavy type with a high saturation of technological equipment. In the case of the installation of reinforced concrete structures, it is necessary to use fast-setting cements to grout the joints.
In the practice of agricultural construction, a combined method of installation is carried out, combining a differentiated method with a complex one (installation of columns within the span, and beams or trusses and cover slabs within one cell).
Depending on the sequence of assembling structures vertically, a method of building up and growing is distinguished. The extension method consists in sequential assembly of structures from bottom to top. This is the main method for assembling structures. The growing method differs in that the installation is carried out starting from the upper tiers. On the ground, the uppermost tier of the structure is assembled, it is raised, then the lower tier is brought in, connected to the upper one, both tiers are raised, etc. This method requires powerful lifting means and can only be used with certain structural solutions of buildings.
According to the method of aiming at the supports, installation is divided into free and forced. With free mounting, aiming at the supports is carried out using flexible slings without restricting the movement of the element in space. Installation accuracy is ensured by visual control. Forced assembly provides for the installation of the elements to be mounted in the design position using special assembly equipment (conductors, manipulators), as well as the directional movement of the element at the time of its installation, using limiting devices and self-locking interlocks at the joints.
The choice of a rational installation method is the most important decision in the work production project. At the same time, the features of the volumetric-constructive solution of this object, the specific conditions of the construction site and the technical and economic indicators of the methods under consideration are taken into account.
40. Installation of prefabricated reinforced concrete structures of one-story industrial buildings.
According to the volumetric planning structure, one-story industrial buildings of the cellular type are distinguished with shed or flat coatings or of a span-equal type with coatings in the form of trusses, shells, folds. For the main industries, one-story industrial buildings with a reinforced concrete frame are designed on the basis of unified standard sections, spans, column steps. When choosing one or another method of installing an industrial building, one should take into account its structural diagram, the necessary sequence of delivery for the installation of technological equipment in individual spans of the building, the location of future technological lines. For one-story industrial buildings of a light type with a reinforced concrete frame, a separate method of mounting the structure is more rational. With this method, after the installation of structures and alignment of the columns, the joints between the columns and the foundation glasses are monolithic. By the beginning of the installation of the crane beams and the pavement structure, the concrete in the support riser must gain at least 70% of the design strength. This condition determines the length of the mounting sections. A single-storey industrial building of a heavy type is assembled mainly by an integrated method. But at the same time, it is necessary to take measures to accelerate the set with concrete at the joints of strength.
In terms of direction, a longitudinal installation is distinguished, in which the building is mounted sequentially with separate spans, and transverse (sectional), when the crane moves across the spans. Long-transverse installation of the building is also used. In this case, the crane, moving along the span, assembles all the columns, and then, moving across the span, conducts sectional assembly. Single-storey industrial buildings are assembled by specialized streams, each of which is provided with a set of assembly and transport machines and the corresponding assembly equipment. For example, a single-span one-storey building can be mounted in 2 streams: installation of columns, roof structures and external fencing structures. Single-storey multi-span buildings can be mounted in several parallel streams.
The installation of the columns should be preceded by the acceptance of the foundations with a geodetic check of the position of their axes and elevations. Before installing the columns, check their dimensions, allowing errors of up to 1 mm, and apply risks that facilitate the installation of the column in the foundation glass or on the head of the sub-columns. Heavy columns are usually mounted from vehicles or pre-laid out with a base facing the foundations. Columns of lightweight type are usually pre-delivered to the installation area and laid out with their tops facing the foundation. Heavy columns are lifted and brought to a vertical position in a pivot or slide manner. The columns are installed in the foundation glasses after the strength of this solution reaches at least 70% of the design. The column, installed in the foundation glass, is centered until the marks coincide with the risks on the upper plane of the foundation. To check the verticality of the column, two theodelites are placed at right angles to the digital and letter axes of the building. In this case, the sighting axis of the theodolite is combined with the risks applied to the glass in the lower part of the column, and then, the theodolite pipe is gradually raised, with a risk at the upper end of the column. The verified columns are fixed in the foundation glass using conductors or wedges. Reinforced concrete wedging after alignment of the column is left in the column. Columns with a height of more than 12 meters are additionally fastened with inventory braces in the plane of their least rigidity.
The crane beams are mounted after the concrete at the junction between the column and the walls of the foundation glass has gained at least 70% of the design strength. The crane beams are mounted in a separate stream or simultaneously with the roof structures. Before lifting, the scaffold devices are hung on the roll for its temporary fixing in the design position, as well as braces for its precise aiming. The axes of the crane girders are verified with a theodolite installed along the axis 1 of the crane girder on a special bracket attached to the first column so that the theodelite is located at a height of 500 mm above the upper plane of the girder. With a span of no more than 18 meters, the axis of the crane beams is verified by measuring the span against each column with a tape measure. Crane beams, crane rails are leveled with a device installed in the middle of the building span at a height of 200-300 mm from the surface of the beam.
Cover trusses are usually assembled from vehicles. In some cases, as well as if it is necessary to enlarge the trusses at the installation site, they are placed in special cassettes, in the mounted span. In this case, the trusses are laid out in such a way that the crane from each position can install the trusses without braces and, if possible, lay the covering slabs without moving. Construction trusses and roof beams are assembled after the installation and fastening of all the underlying structures of the building frame. During installation, the truss is raised, unrolled with a guy line at 90 0. Then they are raised to a height of 0.5-0.7 meters exceeding the mark of the supports, and lowered onto the supports. The correctness of the installation of beams and trusses is controlled by aligning the corresponding marks. To insure the trusses, traverses with semi-automatic grips are used, which provide remote trussing. After lifting, installation and alignment, the 1st truss or beam is fastened with braces, and the subsequent ones are fastened with special struts at the rate of at least 2 for trusses with a span of 24-30 meters. The braces and spacers are removed only after the covering panels have been installed and welded.
Coating slabs are pre-stored in the area of operation of the assembly crane. The number of stacks of slabs and their location is determined from the condition of covering the cells between 2 trusses from one crane station. The coating slabs are mounted immediately after the installation of the permanent fastening of the next truss. This ensures the rigidity of the assembled cell of the building frame. Plates should be mounted with symmetrical loading of the truss, welded to embedded parts and released from slings only after welding at 3 points. After installing the plates, the joints are monolithic.
Installation of wall panels is a laborious process, in which labor costs can be 30-40% of labor costs during the installation of the above-ground part of the building. Installation of wall panels is usually carried out in a separate flow immediately after concrete is set in this area of the required strength at the joints between columns and foundations. Large-sized wall panels up to 12 meters long, as a rule, are mounted from vehicles using wall cranes or special installers in the form of self-propelled tower units equipped with a self-lifting erection platform.
42. Sealing the joints of prefabricated reinforced concrete structures. Installation work in winter conditions. Safety precautions.
The strength of the constants, their spatial rigidity and the stability of the structure, depend on the quality of the sealing of the reinforced concrete assembly joints. Sealing the joint consists of a trace. processes: welding and protection of embedded parts from corrosion, monolithic joints with mortar or concrete mixture, joint sealing (mainly for wall panels).
Labor intensity of sealing joints 75-80% of the total labor intensity of installation of floor slabs and wall panels.
Welding of fittings and embedded parts. Welding of embedded parts and outlets of reinforcement of butt joints starts after checking the correctness of their location and thorough cleaning from dirt, rust, ice.
Outlets of reinforcing bars in the joints and assemblies of prefabricated reinforced concrete structures are welded, depending on the diameter of the reinforcement, with an overlap or with overlays for bars with a diameter of 8 to 20 mm; for bars with a diameter of more than 20 mm, semi-automatic direct current bath welding is used.
The surface of the welded joints should be smooth, finely flaky, and should not have undercuts, underfills, pores and other visible defects. The welder conducting the welding puts a stamp on the joints welded by him and enters the data on the performance of welding work in the log. Depending on the type of connection, the quality of the seam is checked by inspection, drilling and acid etching of the defective areas of the seams in order to eliminate the lack of a hole in the root of the seam. Internal seam defects can be detected using ultrasonic or gamma electroscopy.
Metal parts must be protected against corrosion. Protect electrochemically.
To reduce the labor intensity of sealing joints and to increase the reliability of the joints of the columns of multi-storey buildings, it is necessary to use non-welded glue joints. The most technologically advanced is honeycomb joints.
In such joints, the reinforcement outlets of the column elements to be mounted are inserted with the help of a special conductor into the sockets located at the ends of the previously installed columns.
Milling joints.
Casting of joints is carried out with a sand-concrete mixture or a concrete mixture, in which crushed stone serves as a filler. With a larger joint volume, concrete mixtures are usually used. The duration of the process of monolithing of spatial structures should be minimal. Therefore, quickly hardening cements are used to grout joints. When monolithing the joints between the outer panels of large-panel buildings or between the hinged panels of industrial buildings, sealing is performed, excluding the penetration of air and moisture into the room. Joint sealing works are carried out from suspended cradles or self-propelled towers in the following order:
They clean the joint gaps, cover the joint gaps with insulating mastic using special. pneumatic apparatus, the poroizol gaskets are inserted with a special roller. In this case, the spacers should be 30-50% wider than the gap.
Installation work in winter conditions.
When performing installation work in winter conditions, the most vulnerable point is the joint of prefabricated reinforced concrete structures. When monolithing butt joints in winter conditions, measures should be taken to prevent freezing of concrete in the joint until it reaches critical strength, the value of which depends on the type of structure and the timing of its commissioning. To achieve the critical or design strength with the mortar or concrete before freezing, the joint cavity should be preheated and the concrete or mortar heated to a temperature of at least 20 degrees should be laid, followed by maintaining the required temperature of isothermal heating.
Embedded parts and outlets of fittings in the joints are welded at an outside air temperature of at least -30 degrees.
Joint sealing methods:
Freezing, - introduction of antifreeze additives into concrete, - heat treatment of concrete.
The presence of negative ambient air temperatures imposes certain restrictions on the process of sealing joints. So, the sealing of joints with mastics is allowed at a temperature not lower than -20 degrees.
Safety precautions.
The requirements of the safety rules must be taken into account already at the design stage of the facility. Safe installation should be provided for at the stage of development of the project for the production of installation work. I admit workers to the installation of structural and related work after conducting an introductory briefing, during which they are introduced to the rules of safe work, taking into account the specific features of the bottom building or structure.
I admit specialists who have a certificate of medical examination, which they pass twice a year, for installation and welding work at a height. Climbers are allowed to climb work if they have a grade of at least 4 and have experience of at least one year. All workers must wear hard hats; when working at height, they must wear safety belts. When moving from unit to unit of the mounted structure, workers attach the belt carabiner to the tensioned steel safety rope.
In order to create a safe working environment. the site in the building to be assembled must have warning signs, hazardous zones must be highlighted, openings must be fenced, and workplaces during the performance of work in the evening and at night are sufficiently illuminated.
Special precautions should be taken in windy weather, with a wind of more than 6 points, installation work associated with the use of cranes, as well as at a height and in an open place, should be stopped.
Mounted structures are kept from swaying and rotating by means of guy wires.
During installation, much attention should be paid to electric welding work, because when performing them, in addition to the danger of electric shock, there is also a fire hazard. Do not weld in the rain, thunderstorm, heavy snow or wind. The welder must work in overalls and with an assembly belt.
The main purpose of reinforced concrete structures is to serve as the supporting frame of the building. The longevity and reliability of the structure depends on how correctly and efficiently they are delivered.
The slightest mistakes in the assembly and installation of this building element are fraught with the most serious consequences. Therefore, such work should be carried out by professional and experienced specialists armed with the necessary equipment. The types and methods of installation of steel and reinforced concrete structures are different, but the ultimate goal is the same - to give the structure maximum stability.
Classification of reinforced concrete structures
Installation of metal and reinforced concrete structures depends on the purpose and their design features.
According to the criterion of purpose, structures are divided into:
Foundations;
The first serve as a support for the entire building, the rest - as floors and load-bearing structures, to support the frame elements and transfer forces from one structure to another.
According to the peculiarities of manufacturing, structures are divided into:
Monolithic;
Prefabricated;
Prefabricated monolithic.
Monolithic structures are the most durable and reliable. They are used in cases where a large load on the supporting element is expected. Prefabricated structures are not as strong, are too dependent on weather conditions and can be used where special reliability is not required.
But they are easy to install and easy to transport. Prefabricated monolithic structures have a fairly high strength and, according to this indicator, are not inferior to monolithic ones. Therefore, they are often used in the construction of bridges, in the floors of multi-storey buildings.
Types of work during the installation of structures
Installation of metal and reinforced concrete structures is subdivided into the following types of work:
Foundation installation;
Installation of walls in the basement of the building;
Installation of structural elements of the building frame;
Installation of ventilation elements and blocks;
Installation of internal elements of the building.
Each of these types of work requires adherence to a special technology and the use of those steel and reinforced concrete structures that correspond to the tasks set.
Initial stage of construction
Before installation, preparatory work should be carried out. Since these structures are of considerable weight, it is necessary to think over the approach to the construction site of vehicles and special equipment (for example, cranes).
Further, geodetic work is carried out, which makes it possible to tie the axes of the structure to the terrain. It also determines which structures and in what quantity should be used. Survey of the terrain and preliminary calculations allow you to avoid cost overruns and loss of time for reworking incorrectly mounted structures.
After transportation to the place of assembly, the structures are laid out in the right order. This is a very important and responsible part of the work, because a truss, beam or slab is not a match, it is very difficult to pull it out from under other structures. The basic rule of layout: if the structures are stacked on top of each other, the elements that are installed first of all should lie on top, the bottom row or especially heavy structures are laid on wooden substrates, it is necessary to provide free access of equipment to each structure and the possibility of gripping the part with a crane boom, as well as convenience rafters.
Installation of foundations
The laying and installation of reinforced concrete structures in the pit is carried out according to a pre-drawn scheme, in which the location and assembly of all components are precisely marked. Lighthouse blocks are initially placed in the pit. This is the name of reinforced concrete structures, which are located at the corners of the foundation and at the intersections of the axes of the structure.
Then cushion blocks are laid, between which technological gaps are left (for example, for the passage of cables or pipelines). The blocks of strip foundations should be located on a sand bed.
Next, the foundation walls and basement floors are installed. Floor panels are welded to embedded parts in cushion blocks, and the joints between the panels are filled with cement mortar. Installation of reinforced concrete foundation structures requires constant alignment with a leveling level of the position of the walls, both vertically and horizontally.
Upon completion of the installation, a mounting horizon is installed - a cement layer along the upper part of the walls to reach the design level and level the upper edge. After that, the basement is built, and the basement is closed with slabs that form its ceiling and at the same time the floor of the lower floor.
Precast concrete foundations are installed in a slightly different order. First, a plate is placed on the bottom of the pit, where the glass block is welded. He is placed on a kind of "bed" consisting of cement mortar. Block foundations are installed with a crane, and their setting in the correct position is carried out by weight.
Column installation
Before installation on the columns, on the four faces, the risks are applied to the top and bottom, indicating the axes. Reinforced concrete columns are laid out in front of the installation site in such a way that the crane makes a minimum of movements, and it is convenient for the workers to inspect and fix the structures. The column is installed in a glass, fixed on the foundation.
The column is attached to the crane hook in such a way that it stands upright when lifting;
The crane puts the column in an upright position. Depending on the weight of the column, different lifting methods are used - rotary, sliding turn. Frictional or pin grips are used for railing the columns;
Lowering to the foundation and alignment. It is impossible to remove the column from the crane until its correct position is clearly determined using a level and a theodolite.
The column must stand strictly upright without the slightest tilt. Temporary fixing of the column for its adjustment is carried out using wedge liners.
The next step is to secure the column in the foundation glass. It is produced by injecting concrete mortar into the joints of the column (usually with a pneumatic blower). After reaching 50% of the concrete design strength, the wedge liners can be removed. Further work related to the load on the column, as well as the laying of beams, are carried out only after the mixture has completely hardened.
Installation of beams and roof trusses
Beams and roof trusses are installed either simultaneously with the roof slabs or separately. Installation of metal and reinforced concrete structures of the main part of the building is carried out depending on the design requirements.
Before installing the trusses, all support pads are adjusted and cleaned and the axle marks are applied. After that, the structures are delivered to the installation site, slinging and lifting are performed. When installed on a support, the truss or beam is temporarily secured with metal pipe struts, which are attached before the start of the lifting.
After that, the truss is adjusted and checked for stability and correct installation according to the risks involved. The truss or beam should be positioned so as not to violate the geometry of the building and not to shift relative to the axes of the frame.
Only after a complete check is the final fixing of the element made. Embedded parts are welded to the base plate or column head, as well as to previously installed trusses. The anchor bolt washers should also be welded. Only after the complete installation of the beams and trusses can they be detached.
After the construction of the frame, a horizontal stiffening belt is installed, which is a monolithic reinforced concrete beam passing along the upper ends of the bearing walls. Its task is to ensure the horizontal rigidity of the structure.
Installation of slabs
As with any installation of reinforced concrete structures, the installation of slabs requires preliminary preparation. Scaffolds or fences must be installed on span trusses. There are two main ways of mounting plates - longitudinal and transverse. In the first case, the crane moves along the span, in the second, across the span. Coating slabs are stacked between columns for feeding to the coating site.
The first slab is placed in the place marked in advance on the farm, the rest - right next to it. If the building is frame, the floor slabs are laid after the installation of crossbars, girders and spacer plates, and if the building is frameless, after the walls have been built. When laying the slab on the surface, a "bed" is made from the solution. The excess solution is squeezed out by the plate itself. The first plate should be welded to the truss in four nodes, the subsequent ones in three. Joint joints are sealed with cement and sand mortar.
Installation of wall panels
Wall panels are installed after the building frame has been erected and the floors have been laid. Before lifting, the panels are grouped into cassettes. With this method of storage, the installation of metal and reinforced concrete structures intended for the construction of walls is the most rational. Cassettes can be placed between the wall and the tap, behind the tap, as well as in front of it.
The panels are installed by installers only from the inside of the building. Wall panels are placed along the entire height of the building with a section between two columns. Therefore, in one cassette there must be such a number of panels to cover the entire area along its entire height.
The panel is received by the installers at the junction of this structure with the column. To do this, you need to provide workers with access to these points in advance. If there is no crossover, you will have to install cradles, scaffolds or a lift.
The installation of the first row of panels is of particular importance, therefore their position and compliance with the applied risks are checked especially carefully. The outer panels not only serve as supporting and protective, but also aesthetic functions. Therefore, the seams between the panels must be sealed not only carefully, but very carefully and not exceed the established norms.
Internal wall panels are installed prior to the installation of the upper floor slabs. The panels are fastened to the columns with clamps, to the floor slabs - with struts. The final fixing of the wall panels is done by welding them with the building frame elements.
Features of metal structures
A distinctive feature of metal building structures is their tendency to deformation, significant weight and special precision in manufacturing. Therefore, transporting, laying, lifting and setting up requires special care and attention.
In general, the installation of metal and reinforced concrete structures does not fundamentally differ, but metal products are often prefabricated, which allows them to be assembled not only on the ground, but also directly at the installation site.
PROJECT OF WORK PRODUCTION
for the installation of prefabricated reinforced concrete structures of the "cube 2.5" system
1. General part
1. General part
1.1 This project of work was developed for the installation of prefabricated reinforced concrete structures of the "cube 2.5" system at the facility: "Residential development in the Yugo-Zapadny microdistrict. Buildings N 13, 14, 15. Address: Moscow region, Podolsk.
2. Technological sequence of works
2.1 General data
The frame of the KUB-2 5 system is intended for use in residential buildings and public buildings, as well as in auxiliary buildings of industrial enterprises with up to 15 floors inclusive.
The frame is assembled from factory-made products with subsequent monolithing of the nodes.
The frame of the KUB-2.5 system is designed according to a frame or frame-tie scheme, the transfer of horizontal forces to the columns and stiffeners is ensured by monolithing the floor panels with their transformation into a hard disk in the horizontal plane.
The load-bearing capacity of the floors allows the use of the frame in buildings with a floor load intensity of no more than 1300 kg / m.
The developed frame structures provide for floor heights in buildings of 2.8 m, 3.0 m and 3.3 m with the main column grid of 6.0x6.0 m. For buildings with a height of more than 15 floors, individual development of columns is required.
In the KUB-2.5 system, reinforced concrete compressed-stretched braces are adopted according to an ascending scheme, which ensured the spatial rigidity and stability of the frame-braced version of the system. The bearing capacity of the tie element is determined on the basis of its work on the longitudinal tensile force.
The section of the link element is taken 200x250 mm, reinforcement with 4 load-bearing reinforcing bars, both ends of which are welded to the embedded loops located at both ends of the element.
2.2 Installation of columns and ties
2.2.1 Preparatory work
Before starting the installation of columns on the foundation, the following work must be performed:
Make monolithic glass-type foundations, check the accuracy of the glasses of their binding to the axes of the building. Accept completed constructions according to the act;
Prepare the basement floor;
Verify that the foundation concrete has reached 70% of its design strength.
Before starting the installation of subsequent columns, the following work must be performed:
Mount the floor guard. Close the openings in the ceilings with wooden shields;
Check the correct installation of the underlying columns and take them according to the act;
Prepare the necessary mounting equipment;
The concrete of monolithic structures (seams) of the underlying columns and floors must gain 70% of the design strength.
2.2.2 Sequence of work
2.2.2.1 Work on the installation of columns on the foundation is carried out in the following sequence:
Rinse the glass with water under pressure and make a gravy from M-200 cement mortar, the top of which must correspond to the design level of the bottom of the column;
After the column is fed to the foundation glass, the installers approach it, calm it down from hesitation and lower it into the glass. If the height of the column from the edge of the glass does not exceed 12 cm, then fixing it with wedges from loss of stability can be considered sufficient; if this size exceeds 12 cm, then it is necessary to install special struts, which are removed after installation and embedding of the first floor. During the installation of the column, it is necessary to ensure that the longitudinal risks are located in relation to the adjacent enclosing structures according to Figure 2;
Using longitudinal marks on the edges of the column, align it vertically and horizontally and then fix the column using 4 steel wedges;
The sinuses in the glass should be concreted with fine-grained concrete B25, followed by compaction;
For installers, install a tower tower Aris 1x1.5x9.6 m (it can be replaced with similar ones) and install telescopic struts to the column. Fasten the second end of the struts into the ceiling using anchor bolts;
Fig. 1. Column fixing scheme using wedges
Fig. 2. The layout of the longitudinal marks in relation to the adjacent structures
2.2.2.2 Work on the installation of columns on top of each other is carried out in the following sequence:
At the storage area, insert a trunnion into the through hole of the column at the level of the upper tier and fix it with pins. Tie the rope to the trunnion and the hairpin (for unstitching after the installation of the columns). Attach the rope to the column. Install a clip on the column (for attaching telescopic struts) below the mark of the bottom of the overlap with the ribs down;
At the signal of the slinger, send the column to the installation site, while the installers must be outside the danger zone formed from the fall of the column;
After the column has been supplied to the installation site, the installers should approach it and calm it down from hesitation. Align the columns one above the other and lower them, while the rod of the lower end of the upper column must enter the branch pipe of the upper end of the lower column. Next, it is worth welding the reinforcement according to the project;
For installers, install a tower tower Aris 1x1.5x9.6 m (it can be replaced with similar ones) and install telescopic struts to the column. Fasten the other end of the struts into the ceiling using anchor bolts. The braces may be removed only after the installation of the overlying floor slabs;
After installing the column, unstitch it by pulling the pin out of the trunnion and pulling the trunnion out of the column with a rope.
2.2.2.3 Installation of column connections is carried out in the following sequence:
At the storage site, perform preliminary pairwise assembly of tie elements into a triangle using a mounting spacer;
Weld the support tables to the column;
At the signal of the slinger, send the connection to the installation site, while the installers must be outside the danger zone formed from the loss of the connection. Reinforced concrete ties are installed "in a herringbone" ascending scheme;
After submitting the connection to the installation site, the installers should approach it and calm it down from hesitation. Establish a connection on the tables and weld;
Concreting of supporting structures with fine-grained concrete B15 within the dimensions of the element section.
Fig. 3. The appearance of the column and its nodes
Fig. 4. Column junction
Fig. 5. Tie attachment point
2.3 Installation of floor slabs
2.3.1 General
Floor panels are designed in 2 modifications: single-module with maximum dimensions 2980x2980x160 and two-module - 2980x5980x160. At the ends of the panels, hinge outlets are provided, which provide a monolithic connection of adjacent panels in the building frame, and assembly tables, which in most cases ensure the installation of the ceiling without supporting racks.
Single-module floor panels are divided, depending on their location in the frame, into above-column (panels directly resting on the columns) NP - intercolumnar (panels located between the columnar) MP - and middle (located between the columnar) SP.
2.3.2 Preparatory work
Before installing the floor panels, make sure that:
Column spacing corresponds to design values within tolerances;
Geometrical dimensions of panels (dimensions of diagonals, "propeller shape", etc.), reinforcement outlets, embedded parts, etc. meet the design requirements;
There are no technological beads of concrete that interfere with installation and welding.
2.3.3 Sequence of work
The installation option for 2-modular panels provides the following sequence:
Installation of 1-modular NP panel above the column;
Installation of a 2-module NMP panel;
Installation of a 2-module MSP panel;
Fig. 6. Mounting option for 2-module panels
The installation option for I-modular panels provides the following sequence:
Installation of the NP above-column panel;
Installation of the intercolumnar panel MP;
Installation of the middle panel of the joint venture;
Fig. 7. Mounting option for I-modular panels
2.3.3.1 Installation of panels is carried out in the following sequence:
Install a mounting jig on the column;
At the signal of the slinger, deliver the NP plate to the installation site, while the installers must be outside the danger zone formed from the fall of the plate;
After feeding the slab to the installation site, the installers approach it, calm it down from vibrations and lower it onto the conductor;
Correct the level of the panel using specialized bolts on the jig;
Install telescopic racks under the plate;
Attach the NP panel to the column by welding the slab shell with the column working reinforcement. After completing the welding work, it is allowed to remove the jig;
In the places where the inter-column ties are installed, weld to the shell of the ties of the structure panel of the head of the triangle apex;
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