Course work "Technology of erection of buildings and structures"

Introduction

Installation refers to the assembly and installation of building structures from pre-made elements. Such assembly and installation is carried out using lifting mechanisms.

Erection of building structures is a leading process in construction.

Installation of building structures is a complex mechanized process of assembling a building from elements and structural units of factory manufacture.

Like all complex construction processes, installation consists of basic, preparatory and transport work processes. The result of installation processes can be both construction products in the form of a finished structure, as well as elements of construction products or construction structures, for example stairs or slabs of window openings in buildings with brick walls.

When performing installation works, the constructions and installation diagram are of great importance.

All zero cycle works shall be performed prior to installation works.

Erection of building structures consists of preparatory and basic processes. Preparatory processes include transportation, warehousing and pre-assembly. The main processes are preparation for lifting and lifting of structures, their reconciliation and temporary fixation, grouting of joints and joints, as well as corrosion protection of structures.

The main task during installation works is to reduce the duration of installation cycles and increase the installation accuracy.

Installation methods are the determining factors of the installation process, for the implementation of which work execution projects, process charts and process diagrams of installation of individual structural elements are developed.

About Terminating Joints

Seam Termination-Final mounting operation. Assembly joints of prefabricated elements are divided into joints, assemblies and seams:

joint - place of connection of extreme parts of elements;

assembly - place of connection of several prefabricated elements in length or width;

seam is the place where the prefabricated elements adjoin each other in length or width.

In practice, all of the above compounds are generally referred to as joints. When counting joints and assemblies, they are normalized piece by piece, seams with linear meters. There are joints: bearing and non-bearing; rigid and hinged; dry, monolithic and mixed.

The main operations during sealing of joints of reinforced concrete structures are: protection of reinforcement and embedded parts from corrosion, sealing and insulation (apply to joints of external wall panels and blocks), grouting with mortar or concrete mixture.

Selection of mounting and load gripping devices.

Installation devices include the following inventory devices:

- load-gripping (sling) devices - slings, grips and crossarms, which serve for reliable connection (suspension) of the lifted element to the crane hook and release of the crane hook after temporary attachment of the lifted element;

- devices for temporary fixation and alignment of the installed elements to the design position - conductors, wedges, spacers, bracing, etc.; they must ensure reliable retention of the element after removal of the load gripping devices and bringing it precisely to the design position;

- scaffolds, platforms and fences ensuring convenience and safety of installers operation at height.

Preference should be given to devices that provide automatic or remote disabling. Lifting capacity of slinging devices shall be not less than weight of load to be lifted. Columns with special holes are stroked with crossarms with rods passing into these holes.

When the height to the bottom of the coating is up to 8.4 m, additional stairs and platforms are used. At higher height, curtain stairs and platforms are additionally attached to the column (before its rise).

Load gripping devices for trusses and beams are selected by their weight and length. Before lifting the truss, 1-2 spacers are attached to it, as well as flexible braces for adjusting the position of the truss during lifting. The very first truss is fixed after installation with braces.

To lift slabs measuring 6x3 m, a four-branch sling is used. Extreme plates are equipped with fencing prior to lifting.

Selection and justification of installation methods

Breaking the building into grabs.

The set of installation works consists of a number of sequential processes: installation and grouting of columns, installation of bonds with welding, installation of trusses of plates with welding and grouting, installation of wall panels, etc. Several links of workers with use of several assembly cranes, mechanisms for embedment, welding units can participate in this difficult complex of processes. Therefore, to ensure safety, it is not allowed to work simultaneously in dangerous proximity of several links of workers and mechanisms. It is provided by a clear division of the building in plan into grips. At that, simultaneous operation of two installation cranes is not allowed within such grip.

The length of the grip is taken equal to the length of the temperature block of the building.

Sequence of components installation

Within each grip, depending on the sequence of installation of structural elements, differentiated (separate), complex (combined) or combined (mixed) installation methods are used.

In the differentiated method, the structural elements of the same name are mounted with independent flows combined in time. But this method is not used in the installation of coating structures of single-story industrial buildings, which is associated with the design features of a typical solution.

With the integrated installation method, all structures are reconciled and fixed in one stream within one or more adjacent cells of the building, which form a rigid installation stability. However, this method is practically not used when installing buildings with a reinforced concrete frame, since the conjugation of columns with glass-type foundations provides for the possibility of installing overlying structures on the columns only after concrete reaches a strength of at least 70% in joints, which occurs after 3-4 days. In addition, a significant difference in the mass of different structures makes it inappropriate to install them with one crane.

During installation, the elements of the first two are combined using a combined method. This method is most often used in the installation of structures of single-storey industrial buildings: columns, crane beams and wall fences are mounted in a differentiated way, in separate flows, and substructure and rafter beams, trusses and coating plates are mounted in a single flow.

Installation of the elements is carried out by a combined method: the columns of the substructure trusses and wall panels are mounted by a differentiated method, separate flows, and the rafters and coating plates - by a complex method - in a single flow.

Movement paths of installation cranes

During installation, each boom crane can move along or across the spans of the building. Tower cranes can be placed on one side of the building or on both sides, and sometimes inside the outline of the building being erected.

When placing an boom or tower crane inside the outline of a building, its movement is possible along or across the length of the building (longitudinal or transverse installation method). In single-story buildings, the longitudinal placement of vertical links and crane beams makes it difficult for cranes to move transversely, in this case a longitudinal method is advisable. The transverse method is effective in crane-free buildings at the pitch of columns and trusses of at least 12 m. It allows you to reduce the required departure for the installation of large-sized plates.

Since, in our case, the longitudinal arrangement of vertical links and crane beams complicates the transverse movement of cranes, it is advisable to use a longitudinal mounting method.

Interconnection of transportation, storage and installation of structural elements.

According to the relationship of these processes, installation from an acquired warehouse, with preliminary layout in the installation or installation area directly from vehicles ("from wheels") is distinguished.

Installation from the purchase warehouse requires free space outside the building, but, if possible, in the area of the installation crane. In such a method, the elements to be delivered are stored in stacks, cassettes or pyramids and are only then supplied for installation with installation to the design position. Usually multi-storey buildings are mounted from an object warehouse, since the building area is occupied, and tower cranes have a sufficiently large radius of action.

Preliminary storage in the installation area with layout is typical for single-story buildings, sometimes for the installation of columns of the first tier of multi-story buildings. Most elements are laid out inside the outline of the building, and wall panels are laid out from the outside (in pyramids). This laying method somewhat constrains the mounting zone, but reduces the time for turning the crane boom.

At installation from vehicles the elements deliver on semi-trailers directly in an installation zone, without unloading and warehousing lift in design situation (element-wise) assembly crane at once. The elimination of unloading and storage operations increases the efficiency of the complex process, but increases the cost of forced simple vehicles. To reduce the downtime of the tractor, a "shuttle" method is used when the tractor leaves immediately after delivery of the semi-trailer, leaving it on installation.

Installation "from wheels" requires a very clear organization in the time of transportation and installation, for which an hourly schedule of delivery and installation is drawn up.

In our case, installation of all elements is carried out with preliminary storage in the installation area with layout. This laying method somewhat constrains the mounting zone, but reduces the time for turning the crane boom.

Aiming at the structure is limited-free. Limited-free installation is characterized by the fact that the mounted structure is installed in guide stops, retainers and other devices that partially limit the freedom of movement of the structure, but lead to a decrease in labor costs for temporary attachment and alignment. Method increases efficiency of crane equipment due to reduction of installation cycle time.

Control the position of the element, after setting relative to the coordination axes and elevations, using instrumental reconciliation (theodolite, leveler).

Installation is carried out using the extension method. This method is widespread in the installation of all types of buildings. Installation of elements can be carried out according to all three methods of installation - differentiated, complex and mixed. Installation of structures is carried out from above on previously installed structures, and it includes slinging, lifting to the design position, installation of the structure on supports, temporary attachment and alignment of the position, disassembly and fixation of the structure in the design position.

The method consists in sequential expansion of building elements horizontally along the entire length (along the entire floor area), with continuation of work in the same sequence and on subsequent floors. The mounting elements can be separate structures, enlarged linear elements, flat and spatial blocks. The method makes it possible to organize construction of the building by any modern methods, at any organization of work, to apply a wide variety of complex mechanization of all works, to ensure maximum combination of technological processes in order to reduce the total duration of work.

Technology and organization of installation works

Preparatory work:

Before installation, it is necessary to:

- finish zero cycle operations;

- accept the foundations according to the act and check their compliance; the design provision taking into account the requirements of regulatory documents;

- arrange roads for passage of installation crane and cars;

- prepare sites for storage of columns at their places of installation;

- prepare the necessary mechanisms, equipment and equipment specified in the map.

Transportation of structures:

Elements up to 6 m long are transported on on-board vehicles. Longer elements - on road trains with trailers and on beachless semi-trailers with a mass of elements of more than 14 tons; on trailer trailers - up to 40 tons; on panel, fermo-, block locomotives - up to 35 tons.

Installation of prefabricated elements on vehicles is carried out taking into account the following requirements:

- The elements shall be in a position close to the design position, except for the columns which are carried in the horizontal position;

- it is necessary that the elements are supported by wooden inventory gaskets and liners located in the places indicated in the working drawings for the manufacture of these elements. Thickness of gaskets and liners shall be not less than 25 mm and not less than height of hinges and other protruding parts of elements. Intermediate gaskets shall not be used;

- during multi-level loading of lining and gasket should be placed strictly along one vertical line;

- The elements must be carefully strengthened to prevent overturning, longitudinal and transverse displacement, as well as impacts against each other;

- the factored surfaces of the elements shall be protected from damage.

Installation of columns:

Before installation of columns it is necessary to:

- accept the foundations according to the act (with the appendix of the executive diagram) and check their compliance with the design position taking into account the requirements of regulatory documents;

- apply hairlines of installation axes on four faces at the level of upper plane of foundations;

- close the foundation sleeves with shields to protect against contamination;

- arrange roads for passage of installation crane and cars;

- prepare sites for storage of columns at the place of their installation;

- deliver the necessary installation facilities, accessories and tools to the installation area;

- check position of all embedded parts of columns;

- apply hairlines of mounting axes on side faces of columns.

Columns are mounted in a separate (differentiated) flow along the building.

Columns are pre-laid out at installation places on wooden gaskets with thickness of not less than 25 mm. Before installation, each column must be inspected so that it does not have deformations, damages, cracks, shells, chips, exposed reinforcement, concrete strains. It is necessary to check the geometric dimensions of the column, the presence of a mounting hole, the correct installation of steel embedded parts using roulette.

Strapping of columns is performed by mounting rod passed into special hole of column. It is necessary to provide remote disassembly, eliminating the need to lift the worker to the slinging site after installation of the column in the foundation shell. To carry out a strapping with the help traverses of unified (TsNIIOMTP, RCh45569). Columns are lowered into foundation cup on reinforced concrete linings or on leveling layer of concrete mixture by means of mounting crane.

Place of strapping of column and center of foundation support should be located on one circle, described by radius, equal to departure of crane hook from its mounting parking.

Prior to mounting the columns, the depths of the cups and the length of the columns to be inserted into the cups are determined so that the deviation in the size of the columns can be extinguished by the thickness of the solution layer poured into the cups.

Temporary attachment and alignment of columns in vertical direction is performed by means of wedge inserts. Vertical alignment and correction of columns is performed using jacks; Note here that vertical deviation and displacement of columns axes in lower section must not exceed standard values.

Disassembly of the installed columns should be performed after their reliable fixation in the foundation cups with wedge inserts.

After the columns are reconciled, they are fixed in the design position by concreting concrete joints. Wedge inserts are removed only after concrete acquires the joint strength specified in the work design or when concrete reaches 50% strength.

During installation of columns, it is necessary to check the elevation of the bottom of the foundation shell, the alignment of the hairline on the face in the lower part of the column with the layout risk on the upper face of the foundation, the verticality of the columns, the elevation of the crane console and the column tip. Alignment of column axes and layout axes shall be controlled by two axes, column verticality shall be ensured by means of one or two theodolites on two layout axes. Elevations of support platforms for crane beams and trusses are controlled by geometric leveling.

Installation of substructures:

Installation of adjusting trusses is performed by separate flow. Trusses installation is carried out only after concrete is collected in the monolithic joint of the column with the foundation of the given strength. Geodetic check of reference platform elevations is performed prior to installation and installation horizon is installed. The beams are laid out before lifting during installation by boom cranes within the crane range parallel to the column axis.

Farms are lifted using a crossbeam (KB Glavmosstroy, 701617).

Adjusting trusses are installed with further adjustment. Prior to installation of truss, compensators are laid on column in the form of metal gaskets with width of 610 mm. A set of such gaskets allows vertical alignment of trusses.

Trusses are installed by the "on weight" method. After checking correctness of position relative to control hairlines, trusses are fixed with anchor bolts.

After laying in temporary fixation of trusses geodetic check of their position in plan and in height is performed. The location of the axes and elevation are determined by direct scaffolding or lateral leveling. After final alignment trusses are fixed with columns due to steel strips welded to embedded parts.

Installation of rafters and slabs:

Rafter beams and slabs are mounted in one stream after installation and fixation of all underlying structures of the building frame.

They are mounted according to the scheme: installation of one or two trusses and covering of the cell with coating plates. Control of trusses installation is carried out along the sighting axis, for which purpose a theodolite without a tripod is installed on the tip of the extreme column and the axis is designed on all intermediate heads of the columns.

Stability of trusses during installation is ensured by means of inventory spacers fixed by strubcins on upper belts of trusses installed and already installed.

The first truss at the end of the building is fixed with at least two pairs of braces attached to the foundations of neighboring columns. Spacers are removed as coating plates are laid and welded. At the same time, all permanent connections are established with farms.

In order to ensure the design position of the coating slab, the markings applied to the upper truss belts should be laid. Welding of embedded parts of plates shall be carried out in at least three units of their support on upper belts of trusses.

The cover plates are mounted from one end of the rafter truss to the other, starting from the side of the previously mounted span. When laying the first plate, one installer is located on a staircase fixed on a column, the second, on a plate, a previously installed cell or on a staircase. Subsequent slabs are laid, being on previously mounted slabs.

After installation and fixation of the coating plates, grouting of the joints of the coating plates with B15 solution is started.

Installation of wall panels:

Wall panels are mounted independently after the installation of the building frame and coating is completed.

Slinging of panels with length of 6 meters is carried out by means of two-branch sling.

Wall panels are lifted and fed to the installation site by boom crane E801.

The process of installation of wall panels of single-storey industrial buildings includes:

- unloading of panels with installation in cassettes;

- installation of panels in design position;

- welding of mounting joints;

- sealing and filling of horizontal and vertical joints;

- stitching after panels installation.

The installers check and attach the installed wall panels from the working platforms located on the inner side of the building. Two car-based lifts are used as workstations of installers.

Installers located on site provide guidance and installation of panels to the design position, their reconciliation, temporary and final attachment by welding embedded parts. Before panel is installed, solution is poured onto horizontal surface below installed panel, elastic gasket is installed, mastic layer is applied. Vertical seams are filled with cement mortar after final attachment of panels.

During the works, the size of the seams, the quality of the sealing and the integrity of the face faces of the mounted panels should be monitored.

At geodetic control, accuracy of mounting for panels of the first row and for panels above spans is checked by alignment of axes of the bottom face of the panel with hairlines applied from layout axes on support tables.

Control is carried out in two places of bottom face of panel with steel ruler or lateral leveling. For subsequent rows of panels, alignment of the face of the mounted panel with the faces of the previously installed panel is controlled by lateral leveling using theodolite. At the same time measuring rack is alternately attached to mating faces of panels in two places.

Vertical value of installed panel is controlled on two faces by means of plumb-rack or by method of lateral levelling. The height position is controlled by the size of the difference between the elevations of the upper faces of the installed panels, support tables, and liners by geometric leveling.

The panels are mounted from bottom to top within a zone bounded by two columns.

The solution for the panel butt arrangement is applied to the top face of the panel just before it is installed

Measures for quality control of installation works

Quality control of incoming materials and structures:

The mounting organization accepts the structures coming to the construction site. Acceptance of prefabricated structures is carried out according to certificates for these products taking into account permissible deviations in dimensions and according to picking lists. When receiving delivered items, check :

- presence of OTC stamp of the plant;

- presence of axial hairlines and elevation of the center of gravity of the structure;

- availability of mounting hairlines for one-sided reinforced elements

- absence of damages, correctness of geometric dimensions, location of embedded parts, presence and permeability of channels, holes, etc.

- compliance of the product face with the design requirements;

- absence of deformations, shells, cracks, strakes;

- availability of necessary furrows, niches, quarters, valve outlets, protective coatings at embedded parts.

If the product turned out to be of poor quality, it is married, a corresponding complaint is drawn up with the participation of representatives of the general contractor, the mounting organization and the manufacturer's enterprise. The product is repaired if possible or sent back to the manufacturer. Instead, a new, high-quality product is supplied to the construction site.

Operational quality control:

Operational control of the quality of work is entrusted to the producers of works and craftsmen with the involvement of surveyors and representatives of the construction laboratory.

The quality of individual installation operations characterizes the reliability of building structures and assemblies, their stability and bearing capacity.

Quality of structures installation is checked by geodetic instruments and templates against previously applied axial and other risks and elevations. Geodetic control of accuracy of installation of prefabricated elements into design position consists in step-by-step execution survey - geodetic check of actual position of installed structures in plan and height.

The verticality of single columns is checked after their installation with the help of two theodolites, which are located at right angles along the digital and letter axes of the building. Theodolites are located at a distance from the column so that the angle of inclination of the pipe does not exceed 300.

After verifying the verticality of the row of columns, the upper planes of the cantilevers and ends are leveled, which are supports for girders, trusses and beams. Vertical value of installed panels is checked by rail with built-in level, and deviation from axes by template .

At arrangement of monolithic joints visual and instrumental quality control is performed. During visual inspection of monolithic joints, the following are established: appearance, color, monolithicity, presence of foreign inclusions, surface looseness, porosity of the structure, presence of shells.

At the same time with visual inspection of structures geometrical dimensions, value of supports and displacements, positions of embedded parts, actual position and diameter of reinforcement, thickness of protective layer of concrete, presence of metal corrosion are measured.

Quality control of welds and joints is performed visually and instrumentally. For visual inspection, a hammer is used to pierce welds and open slag inclusions, a bar, a measuring ruler, a template for measuring welds, teeth for cutting welds, etc.

The above tools are used to establish the presence of undercuts, burns, shells, strains, non-conformity of sutures dimensions, porosity and other defects. For a more accurate assessment of the seam bearing capacity, samples are cut and further tested under laboratory conditions. If the weld strength does not correspond to the design values, the assembly is reinforced by welding additional rods or other elements.

Also quality control of welds is carried out by radiometric method. The principle of operation of the device is based on "transmission" of the junction with γ-rays and obtaining an image on a photographic film, as well as electromagnetic waves with recording on a magnetic film and subsequent decoding. These methods and instruments make it possible to carry out a comprehensive assessment of the quality of welded joints with the determination of defects and their scale without destroying samples.

Operational quality control (QQMS) schemes are used to improve control efficiency.

Diagrams must be with the work manufacturer, foreman and foreman.

Results of control with characteristic of defects and diagrams of controlled elements are recorded in cards of operational quality control (QQC).

Defects, deviations from the requirements of SNiP and projects identified during the operational control shall be corrected before the start of subsequent operations .

Quality control of finished products:

Acceptance control is carried out by foremen and craftsmen, taking the work performed from the foremen and evaluating their quality.

At final acceptance of the installed structure the following documentation is required:

- set of structural working drawings with signatures made by persons responsible for the works;

- laboratory analysis documents during welding and grouting of joints;

- geodetic survey materials on inspection of layout axes and installation of structures;

- acts of acceptance of hidden works ;

- logs of installation works, welded works, grouting of joints, sealing of wall panels.

Limit deviations of actual position of installed structures shall not exceed.

Hidden Works Acts:

1 Act on hidden works at grouting of joints of floor slabs.

2 Act on hidden works during sealing of joints between wall panels.