Installation of prefabricated reinforced concrete structures. Installation of reinforced concrete columns. Testing the characteristics of FLC according to SNiPs

1.General installation instructions

3. Installation of columns and frames

4. Installation of crossbars, beams, trusses, floor slabs and coatings

5.Installation wall panels

6. Installation of ventilation units, volumetric units of elevator shafts and sanitary cabins

7. Construction of buildings by lifting ceilings

8. Welding and anti-corrosion coating of embedded and connecting products

9. Casting joints and seams

10. Water, air and heat insulation of the joints of the outer walls of prefabricated buildings

1.General installation instructions

Preliminary storage of structures in on-site warehouses is allowed only with appropriate justification. The on-site warehouse should be located in the area of the assembly crane.

Installation of structures of each overlying floor (tier) of a multi-storey building should be carried out after the design fixing of all mounting elements and achievement by concrete (mortar) of monolithic joints of load-bearing structures of the strength specified in the PPR.

In cases where the strength and stability of structures during the assembly process are ensured by welding field joints, it is allowed, with the appropriate indication in the project, to mount structures of several floors (tiers) of buildings without monolithic joints. At the same time, the project should provide the necessary instructions on the order of installation of structures, welding of joints and monolithic joints.

In cases where permanent connections do not ensure the stability of structures during their assembly, it is necessary to use temporary mounting connections. The design and number of connections, as well as the procedure for their installation and removal, should be indicated in the PPR.

Brands of solutions used in the installation of structures for bedding should be indicated in the project. The mobility of the solution should be 5-7 cm along the immersion depth of a standard cone, except for cases specifically stipulated in the project.

The use of a solution whose setting process has already begun, as well as the restoration of its plasticity by adding water, are not allowed.

Limit deviations from the alignment of landmarks when installing prefabricated elements, as well as deviations of completed mounting structures from the design position, should not exceed the values \u200b\u200bgiven in Table. 12. SNiP 3.03.01-87 "Bearing and enclosing structures".

In the process of installation, measurement control should be carried out, a geodetic executive scheme should be drawn up. The results of the control should be recorded in special journals.

2. Installation of foundation blocks and walls of the underground part of buildings

The installation of glass-type foundation blocks and their elements in the plan should be carried out relative to the alignment axes in two mutually perpendicular directions, combining the axial risks of the foundations with the landmarks fixed on the base, or controlling the correct installation with geodetic instruments.

Block installation strip foundations and basement walls should be made, starting with the installation of lighthouse blocks in the corners of the building and at the intersection of the axes. Beacon blocks are installed, combining their axial risks with the risks of the center axes, in two mutually perpendicular directions. The installation of ordinary blocks should be started after reconciling the position of the lighthouse blocks in terms of and in height.

Foundation blocks should be installed on a layer of sand leveled to the design mark. Limit deviation the mark of the leveling layer of sand from the design should not exceed minus 15mm.

Installation of foundation blocks on bases covered with water or snow is not allowed.

Foundation glasses and supporting surfaces must be protected from contamination.

The installation of basement wall blocks should be carried out in compliance with the dressing. Ordinary blocks should be installed, orienting the bottom along the edge of the blocks of the lower row, the top - along the center axis. Blocks of external walls installed below ground level must be aligned with inside walls, and above - on the outside. Vertical and horizontal seams between blocks must be filled with mortar and embroidered on both sides.

studfiles.net

Collection 07 Installation of prefabricated concrete and reinforced concrete structures

Technical part. 4

Section 01. Industrial buildings and structures. 7

01.01. Foundations and foundation beams. 7

Table 7-1. Laying blocks and slabs of strip foundations, foundations for columns, foundation beams. 7

Table 7-2. The device of a layer of mortar under the soles of the foundations. 9

01.02. Underground structures. 10

Table 7-3. Laying crossbars, floor slabs, wall panels. 10

Table 7-4. Laying concrete over floors.. 12

01.03. Columns and capitals. thirteen

Table 7-5. Installation of columns rectangular section in the glasses of the foundations of buildings and structures. thirteen

Table 7-6. Installation of columns of two-branch solid foundations in glasses. 15

Table 7-7. Installation of two-branch composite columns in foundation glasses. 17

Table 7-8. Installation of columns on subordinate columns, installation of capitals. nineteen

01.04. Beams, crossbars and lintels. 24

Table 7-9. Laying in one-story buildings and structures of beams. 24

Table 7-10. Laying in multi-storey buildings of crossbars, beams, roof structures. 27

Table 7-11. Jumper installation. 35

Table 7-12. Installation in one-story buildings of truss and truss beams and trusses .. 36

01.05. Coating and floor slabs. 43

Table 7-13. Laying of floor slabs, shell panels and p-type slabs. 43

Table 7-14. Laying of floor slabs and installation of supporting sleeves for ventilation devices. 49

Table 7-15. Laying of floor slabs and coatings in multi-storey buildings. 51

01.06. Walls and partitions. 68

Table 7-16. Installation of exterior wall panels one-story buildings. 68

Table 7-17. Installation of panels of external walls of multi-storey buildings. 72

Table 7-18. Installation of panels of partitions of one-story buildings. 77

Table 7-19. Filling vertical seams of wall panels and sealing the seams with mastic. 79

01.07. Installation of steel fasteners. 79

Table 7-20. Installation of steel fasteners. 79

01.08. Stair flights and landings. 80

Table 7-21. Installation of stairs and landings. 80

01.09. The bins are precast-monolithic. 82

Table 7-22. Installation of bins of prefabricated monolithic cells. 82

01.10. Silos for storage bulk materials. 83

Table 7-23. Installation of ring beams and roof slabs during the installation of silo cans. 83

01.11. Fences, gates and gates. 84

Table 7-24. Installation of reinforced concrete and metal fences. 84

Table 7-25. Installation of gates and wickets. 87

01.12. Additional work in areas with seismicity 7 - 9 points. 89

Table 7-26. Reinforcement of prefabricated iron concrete structures. 89

Table 7-27. Casting of crossbars. 89

Table 7-28. Rubber gaskets. 90

Table 7-29. The device of anti-seismic seams. 90

Section 02. Water supply and sewerage facilities. 90

02.01. Construction of capacitive structures. 90

Table 7-30. Installation of wall panels, partitions. 90

Table 7-31. Installation of supports, trays. 95

02.02. Designs of sectional fan cooling towers. 97

Table 7-32. Installation of columns, beams, crossbars, floor slabs and wall panels. 97

Section 03. Constructions of enterprises for the storage and processing of grain. 99

Table 7-33. Installation of walls of silos and bunkers of mills, installation of columns of a silo floor and an inclined bottom. 99

Section 04. Main buildings of thermal power plants. 103

04.01. Constructions of condensation and ash floors. 103

Table 7-34. Installation of structures of condensation and ash floors. 103

04.02. Columns.. 106

Table 7-35. Assembly and installation of columns. 106

04.03. Crossbars, beams, spacers. 108

Table 7-36. Installation of crossbars, beams and spacers. 108

04.04. Floor slabs and coatings. 110

Table 7-37. Laying tiles.. 110

04.05. Wall panels. 110

Table 7-38. Installation of wall panels. 110

04.06. Stairs, bunkers and distribution devices. 111

Table 7-39. Assembly and installation of stairs. 111

Table 7-40. Installation of bunkers. 111

Table 7-41. Installation of switchgear structures. 112

Section 05. Residential and public buildings and administrative buildings of industrial enterprises. 113

05.01. Cellar wall blocks. 113

Table 7-42. Installation of basement wall blocks. 113

05.02. Columns.. 114

Table 7-43. Installation of columns. 114

05.03. Beams, crossbars, lintels. 115

Table 7-44. Laying beams, crossbars, lintels. 115

05.04. Floor panels and coatings in areas with seismicity up to 6 points. 117

Table 7-45. Installation of floor panels and coatings. 117

05.05. Floor panels for construction in areas with seismic activity of 7 - 9 points. 120

Table 7-46. Installation of floor panels and coatings. 120

05.06. Landings and marches. 121

Table 7-47. Installation of platforms, marches. 121

05.07. Wall blocks. 123

Table 7-48. Installing blocks. 123

05.08. External wall panels for construction in areas with seismicity up to 6 points. 125

Table 7-49. Panel installation. 125

05.09. Internal walls and stiffening diaphragms. 128

Table 7-50. Installation of internal wall panels and stiffening diaphragms. 128

05.10. Panels for exterior and internal walls for construction in areas with seismicity 7 - 9 points. 130

Table 7-51. Installation of wall panels. 130

05.11. Partitions are large-panel. 133

Table 7-52. Installation of large-panel partitions. 133

05.12. Slabs of loggias, balconies, canopies, parapets, walls, fences and small structures. 134

Table 7-53. Installation of plates of loggias, balconies, peaks, dividing walls, cornices, protections and small designs. 135

05.13. Bulk blocks. 137

Table 7-54. Installation of bulk blocks. 137

0 5.14. Sanitary cabins, sanitary pallets, elevator shafts, ventilation units, connection and testing of pipelines and electrical wiring of sanitary cabins. 138

Table 7-55. Installation of sanitary cabins and pallets, elevator shafts, ventilation units, connection and testing of sanitary cabin pipelines. 138

05.15. Deformation vertical seams.. 140

Table 7-56. The device of deformation vertical seams in buildings. 140

05.16. Sealing joints of external wall panels and jointing of wall panels and floor panels. 140

Table 7-57. Sealing of joints of external wall panels and jointing. 140

05.18. Stairs from separate steps. 142

Table 7-59. The device of stairs on the finished base of the individual steps. 142

05.19. Metal fences. 142

Table 7-60. Installation of metal fences. 142

Section 06. Engineering networks. 143

06.01. Designs of engineering thermal networks. 143

Table 7-61. The device of impassable channels. 143

Table 7-62. Chambers and fixed shield supports.. 144

Table 7-63. The device of associated unilateral drainage of impassable channels. 146

Section 07. Asbestos-cement structures. 146

Table 7-64. Wall arrangement. 146

Table 7-65. The device of coatings from asbestos-cement slabs in industrial production buildings. 147

Table 7-66. Partition walls. 148

Table 7-67. Installation of partitions 3 m high from asbestos-cement extrusion panels in buildings of industrial enterprises. 148

Table 7-68. Framing doorways in partitions made of asbestos-cement extrusion panels with metal channels. 149

Table 7-69. Closing spaces above doorways in partitions made of asbestos-cement extrusion panels. 149

Table 7-70. Production of fill blocks for cooling towers from asbestos-cement sheets. 149

Table 7-72. Installation of plastic spray nozzles for cooling tower irrigation systems. 150

Section 08. Structures using cement-bonded particle boards. 150

08.01. Partitions on wooden frame. 150

Table 7-73. Installation of partitions in residential buildings. 150

Table 7-74. Installation of partitions with aluminum flashings in buildings industrial enterprises. 152

Table 7-75. Installation of partitions without aluminum flashings in buildings of industrial enterprises. 155

08.02. Partitions on a metal frame. 157

Table 7-76. Installation of partitions in residential buildings. 157

znaytovar.ru

PPR. "cube 2.5" systems,

1. General part

1.1 This project for the production of works was developed for the installation of prefabricated reinforced concrete structures system "cube 2.5" at the facility: " Residential development in the district "South-West". Buildings N 13, 14, 15. Address: Moscow region, Podolsk. 1.2 According to SNiP 12-04-2002 "Labor safety in construction. Part 2. Construction production"clause 3.3, prior to the start of work, the general contractor must carry out preparatory work on the organization of the construction site, necessary to ensure the safety of construction, including: - fencing the construction site; - clearing the territory; - arrangement of temporary roads, equip entrances with wheel washing points, stands with fire-fighting equipment, information boards with marked entrances, entrances, location of water sources, fire extinguishing means - delivery and placement on the territory of the construction site or outside it of inventory sanitary, industrial and administrative buildings and structures; - arrangement of places for storing materials and structures. The completion of the preparatory work must be accepted according to the act on the implementation of labor safety measures, drawn up in accordance with SNiP 12-03-2001 "Labor safety in construction. Part 1. General requirements". 1.3 The main standards and guidelines used in the development - SNiP 12-03-2001 "Labor safety in construction", part 1 .; - SNiP 12-04-2002 "Labor safety in construction", part 2 .; - PPB-01-03 "Fire safety rules in Russian Federation"; - Decree of the Government of the Russian Federation of February 16, 2008 N 87 "On the composition of sections project documentation and requirements for their content"; - SNiP 5.02.02-86 "Norms for the need for construction tools"; - Guidelines on the procedure for developing projects for the production of work by hoisting machines and technological maps loading and unloading operations. RD-11-06-2007. - SNiP 3.01.03-84 "Geodetic work in construction";

SNiP 3.03.01-87 "Bearing and enclosing structures".

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 the number of floors up to 15 inclusive. The frame is assembled from prefabricated products with subsequent monolithic nodes. The frame of the KUB-2.5 system is designed according to a frame or frame-and-frame scheme, the transfer of horizontal forces to the columns and stiffeners is ensured by monolithic floor panels with their transformation into HDD in the horizontal plane. The bearing capacity of the floors allows the use of the frame in buildings with a load intensity per floor of not 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, it is necessary individual development columns. In the KUB-2.5 system, reinforced concrete compressed-tensioned brace braces were adopted in an ascending pattern, which ensured spatial rigidity and stability of the frame-braced variant of the system. The bearing capacity of the connection element is determined from the calculation of its work on the longitudinal tensile force. The section of the element of connections is accepted 200x250 mm, reinforcement with 4 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 monolithic foundations glass type, check the accuracy of the execution of the glasses of their binding to the axes of the building. Completed designs are accepted according to the act; - prepare the basement floor; - make sure that the foundation concrete has gained 70% of the design strength. Before starting the installation of subsequent columns, it is necessary to perform the following work: - mount the ceiling fence. Close the openings in the ceilings with wooden shields; - check the correctness of the installation of the underlying columns and accept them according to the act; - prepare the necessary mounting equipment; - concrete monolithic structures(seams) of the underlying columns and floors should gain 70% of the design strength. 2.2.2 Sequence of works 2.2.2.1 Installation of columns on the foundation is carried out in the following sequence: - rinse the glass with water under pressure and make a grout from M-200 cement mortar, the top of which must correspond to the design mark of the bottom of the column; - at the storage site, insert a trunnion into the through hole of the column at the level of the upper tier and fix it with pins. Tie a rope to the trunnion and stud (for bridging after mounting the columns). Attach the rope to the column. Install a clip on the column (for attaching telescopic struts) below the mark for the bottom of the overlap with the ribs down; - at the signal of the slinger, move 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 is delivered to the foundation glass, the installers approach it, calm it down from vibrations 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 buckling can be considered sufficient; if this size exceeds 12 cm, then it is necessary to install special struts, which are removed after installation and monolithic 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 enclosing structures adjacent to them according to Figure 2; - using longitudinal marks on the sides of the column, align it vertically and horizontally, and then fix the column with 4 steel wedges; - concrete the sinuses in the glass with fine-grained concrete B25, followed by compaction; - for the installers to install the Aris tower 1x1.5x9.6 m (it is possible to replace it with similar ones in terms of characteristics) and install the telescopic struts to the column. Fasten the second end of the struts to the ceiling with anchor bolts; - after mounting the column, untie it by pulling the pin out of the trunnion and pulling the trunnion out of the column with a rope.

Fig.1. Scheme of fixing the column with wedges

Fig.2. Scheme of the location of longitudinal scratches in relation to adjacent structures

2.2.2.2 Installation of columns on top of each other is carried out in the following sequence: - at the storage site, insert a trunnion into the through hole of the column at the level of the upper tier and fix it with pins. Tie a rope to the trunnion and stud (for bridging after mounting the columns). Attach the rope to the column. Install a clip on the column (for attaching telescopic struts) below the mark for the bottom of the overlap with the ribs down; - at the signal of the slinger, move 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 delivered to the installation site, the installers should approach it and calm it down from vibrations. Align the columns one above the other and lower, 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 the installers to install the Aris tower 1x1.5x9.6 m (it is possible to replace it with similar ones in terms of characteristics) and install the telescopic struts to the column. Fasten the second end of the struts to the floor with anchor bolts. The braces may only be removed after the installation of the overlying floor slabs; - after mounting the column, untie 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 ties is carried out in the following sequence: - on the storage site, perform a 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, apply the connection to the installation site, while the installers must be outside the danger zone formed from the fall of the connection. Reinforced concrete ties are installed "herringbone" in an ascending pattern; - after the connection has been delivered to the installation site, the installers should approach it and calm it down from vibrations. Set the connection on the tables and weld; - perform concreting supporting structures fine-grained concrete B15 within the dimension of the section of the element.

Fig.3. Appearance of the column and its nodes

Fig.4. Column connection node

Fig.5. Ties attachment point

2.3 Installation of floor slabs

2.3.1 General data Floor panels are designed in 2 modifications: single-module with maximum dimensions 2980x2980x160 and two-module - 2980x5980x160. At the ends of the panels there are hinged outlets, which provide a monolithic connection of adjacent panels in the building frame, and mounting tables, which in most cases provide 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 supported by columns) NP - inter-column (panels located between above-column) MP - and middle (located between annular) SP. 2.3.2 Preparatory work Before installing the floor panels, make sure that: - the distance between the columns corresponds to the design values within tolerances; - geometric dimensions of the panels (diagonal dimensions, "propeller ratio", etc.), reinforcing outlets, embedded parts, etc. meet design requirements; - there are no technological influxes of concrete that interfere with installation and welding. 2.3.3 Sequence of work execution The installation of 2-module panels provides for the following sequence: - installation of a 1-module NP above-column panel; - installation of a 2-modular NMP panel; - installation of a 2-modular MSP panel;

Fig.6. Mounting option for 2-module panels

The installation option for I-modular panels provides for the following sequence: - installation of the above-column panel NP; - installation of the MP intercolumn panel; - 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, move the NP slab to the installation site, while the installers must be outside the danger zone formed from the fall of the slab; - after the slab has been delivered to the installation site, the installers should approach it, calm it down from vibrations and lower it onto the conductor; - adjust the level of the panel with the help of specialized bolts on the conductor; - install telescopic racks under the stove; - attach the NP panel to the column by welding the shell of the plate with the working reinforcement of the column. After performing welding work, it is allowed to remove the conductor; - in the places of installation of inter-column ties, weld the top of the triangle to the shell of the ties of the structural panel;

docs.cntd.ru

Methods of installation of reinforced concrete structures - Special types of work in construction

When mounting prefabricated structures, various gripping devices are used, which must be strong enough, ensure the safety of installation and quick slinging of the mounted products. Slinging is called the capture of the structure with a cable (sling) and hanging it from the crane of the lifting mechanism.

Loops for gripping the product with a crane are laid during the manufacturing process of the product. For slinging long elements, special gripping devices are used - traverses or traverse beams. On fig. 111 shows the slinging of various elements of precast concrete structures and traverses.

Rice. 111. Slinging prefabricated reinforced concrete elements:a - beams; b - traverses for lifting beams; c - slinging of the floor slab; g - capturing the column with a steel cable; d - slinging of the column; e - slinging a flight of stairs

When slinging, it is necessary to pay attention to the correct choice of gripping points for structures. So, in columns, such a point should be above the center of gravity. The places of capture of trusses are appointed in such a way that in the rods of the truss there are no forces that are greater than the calculated ones or the opposite of them in sign.

Installation of buildings and structures, depending on design features produced by methods of building, growing, sliding, turning.

The extension method consists in first installing the lower prefabricated elements (shoes or foundation blocks), then mounting the columns. After their fixing, beams and crossbars are laid and other products are installed: panels, slabs and flooring, arches, trusses and roofing slabs. This most common method of assembly from the bottom up is used to erect structures of multi-storey residential, public and industrial buildings, multi-tiered industrial buildings, blast furnace facilities, tanks, cooling towers, etc. (Fig. 112).

Rice. 112 Scheme of installation of a beam by way of building up

The method of growing consists in the fact that first the upper part of the structure is assembled on the ground, which is attached at a height greater than the penultimate tier. The second tier is mounted under the first and attached to it. Further, both tiers are raised to the height of the third tier from the top, which is also collected on the ground, etc. In this way, casings of blast furnaces and tanks are assembled from metal round rings (tsargs).

The sliding method is characterized by the fact that the entire structure or a large part of it is assembled at the level of the structure's supports, then moved along temporary laid tracks and placed in the design position. This method is common during the installation of superstructures of bridges, twin trusses, etc., and only in those cases when it is impossible to move the installation cranes along the structure. On fig. 113 shows the individual stages of tank installation.

Rice. 113. Installation of the tank by the method of growing with the help of four masts: a, b, c, d - separate stages of installation

To move structures during sliding, winches with chain hoists and horizontal jacks are used (Fig. 114).

Rice. 114. Scheme of sliding of three split span structures of the bridge without a device intermediate supports

Heavy columns, frame structures, poles of power lines, contact networks and other structures with significant weight are lifted by turning or sliding.

When mounting by turning, the supporting part of the structure (columns) is pivotally attached to the foundation; first, the column is turned by a crane in vertical plane around her shoe, then slightly lifted and placed on the foundation. At the heel of the column, a pull cable should be provided.

If the lifting capacity of the crane is insufficient, the structure is lifted by sliding. For example, a column is laid so that its supporting part is located near the foundation. When raised, the base slides at ground level towards the foundation on pre-laid rail decks. Regardless of the method used, the assembled parts of the structure at all stages of installation must be stable and durable.

Prior to the installation of reinforced concrete elements, the dimensions and geometric shape of the products, the correct laying of reinforcement and embedded parts and the reliability of their fastening, the dimensions and location of the grooves, niches and holes, the quality and condition of the external finish of the products are checked. The issue of the possibility of mounting products with deviations exceeding the tolerances is resolved in each individual case by the leading technical staff.

The values of tolerances for the manufacture of some reinforced concrete products are given in table. 14.

Table 14 - Tolerances for the manufacture of reinforced concrete products

Deviations of the actual dimensions of large concrete blocks from the design ones should be such that after installation no additional plastering of the structure is required. To do this, the tolerances must not exceed: the thickness of the block ± 2 mm; in height ±4 mm; along the length ±4 mm; by the difference of the diagonals of each surface of the block ±4 mm; according to the position of embedded parts and ventilation ducts ± 5 mm.

If the blocks of external walls have a rusticated (roughly trimmed) facade surface, which makes it possible to somewhat hide the inaccuracy in the thickness of the block, then its thickness tolerance can be increased to ± 5 mm.

The deviation of the block faces from the vertical should not be more than 2 mm per one meter of height.

svaika.ru

Installation of precast concrete structures

Precast concrete structures work in accordance with the project only if they rest on the supports in a certain way and are fixed to them motionlessly. A recurring mistake in the construction of an individual house is the inaccuracy of marking, as a result of which precast concrete beams are used to cover large spans. In this case, the support length is shorter than necessary, the load is transferred to a smaller area and there is a danger that the beam will break or the support will “crumple”.

Often, beams of a different type than those provided for by the project are built into the ceiling, this is allowed if their length corresponds to the required one, and the bearing capacity is higher. Although the beams look the same externally, their load-bearing capacity can vary by more than a factor of two depending on the number and location of the reinforcement. The installation of a random beam with an indefinitely small bearing capacity, not according to the project, will cause its destruction already in the process of building the floor of the house. In such cases, the floor may not collapse, but the deflection will be greater than expected. Due to the deflection along the contact boundary of the beam and the floor elements, cracks appear on the lower part of the floor and it is impossible to eliminate them by periodic whitewashing - they appear again and again due to structural movements under the action of variable loads.

The biggest mistake is laying the beams in the wrong position - on its side or upside down. The bearing capacity of reinforced concrete beams, unlike wooden beams, corresponds to the design one only in a certain position; if they are turned over, they will collapse, since they were designed and reinforced only for this position.

All changes in the original design require additional calculations, since collapse of the ceilings is possible, for example, if short beams are connected by simple welding of the ends of the reinforcement and the joint is filled with concrete, then the ceiling will collapse even during construction. This kind of build-up of structures cannot be reliably performed. It is not recommended to work with reinforcement, in which the bearing capacity decreases sharply during welding. Additional concreting does not ensure the proper quality of the connection, since at the place of welding the concrete under the action high temperature loses its strength. Alterations of precast concrete beams on construction site unacceptable; it is not allowed to lengthen, shorten, embed upside down or on the side.

Precast concrete beams are supported by load-bearing walls or other structures, their ends are fixed with a stiffening belt to prevent displacement. The reinforced concrete stiffening belt is a monolithic concrete beam that runs along the top of the load-bearing walls and provides horizontal rigidity to the building. Before making the stiffening belt, reinforced concrete beams or floor panels are laid. It should be borne in mind that in areas with a cold climate, the stiffening belt can cause freezing of the walls in the overlap zone.

Often they make such a mistake - having reached the top of the wall, to the surface where the stiffening belt begins, they lay beams and floor elements, but they no longer have the opportunity to stretch the reinforcement in the lower part of the stiffening belt under the laid beams (or through them). This error can be prevented.

The simplest solution is to install a support purlin along the wall that supports the ceiling until the stiffener is concreted. Often, with the help of a support run, floor beams are raised and longitudinal reinforcement is carried out under them and a stiffening belt is concreted.

Rice. 1. Incorrect laying of the precast concrete lintel; 1 - correctly laid reinforced concrete lintel, 2 - lintel laid flat, 3 - wall

Rice. 2. Laying precast concrete beams using a support run; 1 - prefabricated reinforced concrete beam, 2 - rack, 3 - run, 4 - formwork, 5 - reinforced concrete stiffening belt, 6 - half-brick wall

When erecting ceilings from prefabricated panels, the formwork is moistened before concreting. At the same time, a lot of water gets into the internal cavities of the panels. If the water does not flow out from there before concreting, then under the influence of frost in winter the ceiling will crack, and its bearing capacity will decrease. In addition, in the spring, moisture emerges through cracks from the ceiling and destroys the whitewash. The described phenomenon also occurs when using trough-shaped floor elements that accumulate rain water, which either freezes in winter or constantly moistens the structure. The solution may be to drill holes at the lowest point to drain the accumulated water.

Rice. 3. Freezing of water in the internal cavities of the floor slab; 1 - ice formation, 2 - cracks, 3 - reinforced concrete stiffening belt, 4 - half-brick wall, 5 - concrete screed; 6 - floor covering

Very often, when filling the ceiling with elements, the necessary layer of mortar is not applied, which ensures the mobility of the elements, which are displaced in the finished ceiling and cracks appear on the plaster.

Sometimes the wrong technology is used for laying prestressed beams filled with elements in the form of hollow inserts. They do not take into account, and often do not know that the floor can withstand the design load only if the seams between the beams and the floor elements are sealed with concrete. This concrete is taken into account when calculating the bearing capacity, but if it is simply laid and left without maintenance, it will “burn out” and the ceiling will not reach the design capacity.

Building garden house- Installation of prefabricated reinforced concrete structures

gardenweb.ru

Reinforced concrete structures in modern construction are used more often than other types. building materials. In most countries the globe they have received recognition and practical application due to the possession of a number of positive characteristics. The most significant of them are the insignificance of the costs incurred for their production and sale, the ability to take any required form, reliability and long-term operation.

Reinforced concrete structures have found their application in the construction of facilities designed for different purposes. These can be residential buildings, shopping centers, structures erected in order to carry out production processes on them. Reinforced concrete products are still used in machine and shipbuilding.

Reinforced concrete structures consist of reinforcement and concrete mix. The latter contains building materials such as sand, gravel, crushed stone, etc.

Varieties of reinforced concrete structures

Reinforced concrete structures, depending on the method of their further use, exist in several forms. It's about about monolithic, prefabricated and prefabricated-monolithic types.

Monolithic reinforced concrete structures

Manufactured directly at the construction site. They are necessary when carrying out the heaviest loads in the construction process, such as foundations and frameworks of structures. The installation of monolithic reinforced concrete structures is carried out through the following operations: construction of a temporary form for reinforced concrete, installation of reinforcement, laying the concrete mix, compacting it and applying measures to protect the hardening concrete from various influences.

Precast concrete structures

Manufactured on site using prefabricated parts. They are used effectively in the construction various types buildings, since such devices can be built in all weather conditions. They are distinguished by high manufacturability and transportability.

Precast-monolithic reinforced concrete structures

They combine the simultaneous use of precast and monolithic reinforced concrete, functioning under load by connecting into a single whole. This is realized by reliably monolithic both parts. Such reinforced concrete is considered very economical due to the possibility of using the best qualities of one and the other of its type. These products are most often used in ceilings of high-rise buildings, bridges, flyovers, etc. The main advantage of precast-monolithic reinforced concrete structures is a smaller amount of steel used and a high rate of spatial rigidity.

Installation of reinforced concrete structures

The initial stage of the installation of reinforced concrete structures is a preliminary calculation of the amount of required building materials. Due to the possibility of using latest methods labor in the installation process, the construction time of facilities is greatly reduced. Installation of products is carried out directly from vehicles. This allows you to significantly reduce the cost of loading and unloading operations and reduce the area required for these operations.

The complex of works on the installation of reinforced concrete structures includes preliminary and installation operations, as well as operations using vehicles. Actions requiring the use of transport and preliminary work consist of delivery, acceptance, unloading, unfolding of structures, their placement on the installation site.

Installation operations for these products may include activities such as:

Installation of the foundation and walls of that part of the structure that is underground;
installation of structural details of those parts of structures that should be placed above the ground. We are talking about columns, beams, frames, slabs, etc.;
installation of blocks used for the manufacture of hoods and natural ventilation of facilities under construction;
equipment installation.

Positive aspects of using reinforced concrete structures

Among the main advantages of the described products are the following:

High indicators of strength and reliability, possible due to the combination of concrete mix and steel reinforcement, which are part of the structure of structures used in different purposes;
the indispensability of reinforced concrete structures in construction, produced in cold period, since they are installed on the same high level at any air temperature;
reduction of construction time;
insignificant costs in the production and implementation of structures, possible due to the use in their manufacture of materials that are present in the natural environment and make up the majority (90%) of the components of the concrete mixture. We are talking about sand, gravel, crushed stone, etc .;
good indicators of resistance to outside influence;
high fire resistance;
manufacturability, allowing to expand the possibilities of building facilities. This is facilitated by the ability of structures to take the required shape.

Weaknesses in the use of reinforced concrete structures

Due to the severity of the described products, there is an increase in transport costs that occur during their movement. The cost of installing structures also increases, due to the same reasons.

psfstroymaster.ru

Reinforced concrete monolithic structures: device features

At present, the installation of concrete and reinforced concrete monolithic structures is an integral part of industrial and civil construction, and is regulated by SNiP 3.03.01-87 of the USSR Goskomstroy, which replaced all previous SNiPs.

There are two options for the manufacture of reinforced concrete products - this is the factory workshop (prefabricated construction) and the construction site itself (monolithic construction), and the second option is much more common, as it allows you to arbitrarily vary the dimensions of the structure. Below we will focus on the second method, which is also used at home, and in addition, we will show you a video in this article as an addition to the topic under discussion.

Manufacturing methods

Note. It is customary to call concrete an artificial building material that is made by molding a binder (mainly cement) and fillers such as crushed stone and gravel sand, mixing it all with water. Most often, this mixture is poured onto a reinforcing cage, so that concrete can be produced at the construction site. and reinforced concrete structures.

Differences between prefabricated and monolithic structures

In accordance with the ENiR for concrete and reinforced concrete structures, prefabricated and monolithic construction is used for the construction of buildings and structures, where the first option involves the construction of certain architectural forms using blocks, reinforced concrete slabs ceilings and panels that are manufactured in the factory.
Such assembly elements are manufactured in the factory according to a certain standard, but with different sizes, so that they can be used in projects of any size and technical complexity. The advantage of this assembly is that it does not take time to produce the materials, thus reducing the design construction time.

If a structure is erected in a monolithic way, then this automatically allows you to design it with any number of floors, and the assembly itself here can have any shape, since reinforcement and pouring are carried out directly at the construction site. For the arrangement of monolithic structures, such works as the installation of formwork, reinforcing work (assembly of reinforcing cages), as well as pouring and vibrotamping of concrete are carried out. All these works are laid down in advance according to the HPES in the project plan.

Monolithic construction and reinforcement

In total, the design of reinforced concrete monolithic structures consists in a reinforced concrete base erected by pouring mortar onto a reinforcing cage, and all together it represents a complex of columns and diaphragms, united by ceilings, which are made in the same way.

Thanks to the savings in building materials and energy resources, the price of such a project is lower than that of a prefabricated one, although its implementation takes more time. Another advantage in the construction of structures of this type can be called self-supporting walls, which in total reduces the weight of the box by 2-3 times compared to the same brickwork.

All this allows you to create a free layout, reaching a high architectural level, where the installation instructions are set by the designer himself, which ensures a very high comfort of the premises.

Despite all the advantages, one can note the great labor intensity of such a process, where from 40% to 50% of all actions consist in the performance of reinforcement work, in addition, approximately 70% of them have to be performed manually. It is impossible to put this on stream, because almost all projects are purely individual, where solutions that are unique in other structures are required.

Note. To reduce labor costs on large construction sites, part of the work is transferred to the reinforcement shop. Sometimes such shops can be equipped in the immediate vicinity of the construction site.

formwork

In addition to the manufacture and installation of reinforcing cages and before the preparation and pouring of concrete, during the erection of monolithic structures, formwork is carried out, which is responsible for creating the shape of the poured structure.

According to the type of material, they can be divided into:

wooden,
metal,
wood-metal,
plastic,
metal-plastic and
even on pneumatic (inflatable).

Most often, inventory formwork is used, which is quickly assembled and disassembled by hand, and at the same time, the assembled structure is quite compact and does not interfere with concreting (pouring).

According to the types of formwork, they are divided into two classes, and one of them is a stationary assembly, when the assembled structure is used only once on one specific object. This approach requires big expense building materials (most often these are boards and timber), although it is quite difficult to do without this for individual design.

Reversible formwork is much cheaper, which consists of many elements such as shields, supports and clamps.

But such formwork can be:

Climbing - for structures with constant and variable cross-section such as pipes, silos;
Mobile or horizontally rollable - for arches and shells of double curvature;
Movable or sliding vertically - for silos, bridge supports, etc.

Note. In monolithic construction, cutting reinforced concrete with diamond wheels and diamond drilling holes in concrete are produced in a similar way to the same processes for precast concrete products made in the factory.

Conclusion

In conclusion, it should be said that the acceptance of monolithic reinforced concrete structures must be carried out strictly in accordance with SNiP 3.03.01-87. That is, this includes not only the structural strength of concrete, but also the surface roughness, which must fully comply with the design plan.

PROJECT OF WORK PRODUCTION
for the installation of prefabricated reinforced concrete structures of the "cube 2.5" system

1. General part

1.1 This project for the production of works 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.