General provisions

Long-span buildings are those in which the distance between the supports (load-bearing structures) of the coverings is more than 40 m.

Such buildings include:

− workshops of heavy engineering factories;

− assembly shops of shipbuilding, machine-building plants, hangars, etc.;

− theaters, exhibition halls, indoor stadiums, train stations, covered parking lots and garages.

1. Features of long-span buildings:

a) large dimensions of buildings in plan, exceeding the radius of action of erection cranes;

b) special methods installation of coating elements;

c) presence in some cases under coverage large parts and building structures, shelves, stands of indoor stadiums, foundations for equipment, bulky equipment, etc.

2. Methods for constructing long-span buildings

The following methods are used:

a) open;

b) closed;

c) combined.

2.1. The open method is that first, all the building structures located under the roof are erected, i.e.:

− shelves (single or multi-tiered structure under the roof of industrial buildings for technological equipment, offices, etc.);

− structures for accommodating spectators (in theaters, circuses, indoor stadiums, etc.);

− foundations for equipment;

− sometimes cumbersome technological equipment.

Then the covering is arranged.

2.2. The closed method consists of first removing the covering, and then erecting all the structures underneath it (Fig. 18).

Rice. 18. Scheme of construction of the gym (cross section):

1 – vertical load-bearing elements; 2 – membrane coating; 3 – built-in premises with stands; 4 – mobile jib crane

2.3. The combined method consists of first performing all the structures located below the covering in separate sections (grips), and then constructing the covering (Fig. 19).

Rice. 19. Fragment of the construction plan:

1 – installed building covering; 2 – shelf; 3 – foundations for equipment; 4 – crane tracks; 5 – tower crane

The use of methods for constructing large-span buildings depends on the following main factors:

− on the possibility of locating load-lifting cranes in plan in relation to the building under construction (outside the building or in plan);

− on the availability and possibility of using crane beams (overhead cranes) for the construction internal parts building structures;

− on the possibility of installing coatings in the presence of completed parts of the building and structures located under the coating.

When constructing long-span buildings, a particular difficulty is the installation of coverings (shells, arched, domed, cable-stayed, membrane).

The technology for constructing the remaining structural elements is usually not difficult. The work on their installation is discussed in the course “Technology of Construction Processes”.

It is considered in the course of TSP and will not be considered in the course of TVZ and C and the technology of beam coverings.

3.1.3.1. TVZ in the form of shells

Behind last years a large number of thin-walled spatial reinforced concrete covering structures in the form of shells, folds, tents, etc. have been developed and implemented. The effectiveness of such structures is due to more economical consumption of materials, lighter weight and new architectural qualities. Already the first experience in operating such structures made it possible to discover two main advantages of spatial thin-walled reinforced concrete pavements:

− cost-effectiveness resulting from a more complete use of the properties of concrete and steel compared to planar systems;

− the possibility of rational use of reinforced concrete to cover large areas without intermediate supports.

Reinforced concrete shells, according to the method of construction, are divided into monolithic, assembly-monolithic and prefabricated. Monolithic shells entirely concreted at the construction site on stationary or mobile formwork. Prefabricated monolithic shells can consist of prefabricated contour elements and a monolithic shell, concreted on movable formwork, most often suspended from mounted diaphragms or side elements. Prefabricated shells assembled from separate, pre-fabricated elements, which, after installing them in place, are joined together; Moreover, the connections must ensure reliable transfer of forces from one element to another and the operation of the prefabricated structure as a single spatial system.

Prefabricated shells can be divided into the following elements: flat and curved slabs (smooth or ribbed); diaphragms and side elements.

Diaphragms and side elements can be either reinforced concrete or steel. It should be noted that the choice of design solutions for shells is closely related to construction methods.

Double shell(positive Gaussian) curvature, square in plan, formed from prefabricated reinforced concrete ribbed shells And contour trusses. The geometric outline of shells of double curvature creates profitable terms static work, since 80% of the shell area works only in compression and only in the corner zones there are tensile forces. The shell of the shell has the shape of a polyhedron with diamond-shaped edges. Since the slabs are flat and square, the diamond-shaped edges are achieved by sealing the seams between them. Average standard slabs are molded with dimensions of 2970×2970 mm, thicknesses of 25, 30 and 40 mm, with diagonal ribs 200 mm high, and side ribs 80 mm high. The contour and corner slabs have diagonal and side ribs of the same height as the middle ones, and the side ribs adjacent to the edge of the shell have thickenings and grooves for the outlets of the contour truss reinforcement. The connection of the slabs to each other is carried out by welding the frame releases of the diagonal ribs and cementing the seams between the slabs. A triangular cutout is left in the corner slabs, which is sealed with concrete.

The contour elements of the shell are made in the form of solid trusses or prestressed diagonal half-trusses, the joint of which in the upper chord is made by welding overlays, and in the lower - by welding the outlets of the rod reinforcement with their subsequent concrete coating. It is advisable to use shells to cover large areas without intermediate supports. Reinforced concrete shells, which can be given almost any shape, can enrich architectural solutions for both public and industrial buildings.

Rice. 20. Geometric schemes of shells:

A– cutting with planes parallel to the contour; b– radial-circular cutting; V– cutting into diamond-shaped flat slabs

In Fig. Figure 21 shows geometric schemes for covering buildings with a rectangular grid of columns with shells made of cylindrical panels.

Depending on the type of shell, the size of its elements, as well as the dimensions of the shell in plan, installation is carried out various methods, differing mainly in the presence or absence of scaffolding.

Rice. 21. Options for the formation of prefabricated cylindrical shells:

A– from curved ribbed panels with side elements; b– the same with one side element; V– from flat ribbed or smooth slabs, side beams and diaphragms; G– from curved panels large sizes, side beams and diaphragms; d– of arches or trusses and vaulted or flat ribbed panels (short shell)

Let's consider an example of the construction of a two-span building with a covering of eight square-plan shells of doubly positive Gaussian curvature. The dimensions of the coating structural elements are shown in Fig. 22, A. The building has two spans, each of which contains four cells measuring 36 × 36 m (Fig. 22, b).

The significant consumption of metal for supporting scaffolding during the installation of double-curvature shells reduces the efficiency of using these progressive structures. Therefore, for the construction of such shells up to 36 × 36 m in size, rolling telescopic conductors with mesh circles are used (Fig. 22, V).

The building in question is a homogeneous object. Installation of coating shells includes the following processes: 1) installation (rearrangement) of the conductor; 2) installation of contour trusses and panels (installation, laying, alignment, welding of embedded parts); 3) monolithization of the shell (filling of seams).

Rice. 22. Construction of a building covered with prefabricated shells:

A– design of the coating shell; b– diagram of the division of the building into sections; V– diagram of the conductor’s operation; G– the sequence of installation of covering elements for one area; d– the sequence of construction of the covering in sections of the building; I–II – numbers of spans; 1 – contour shell trusses, consisting of two half-trusses; 2 – covering slab measuring 3×3 m; 3 – building columns; 4 – telescopic conductor towers; 5 – mesh conductor circles; 6 – hinged supports of the conductor for temporary fastening of elements of contour trusses; 7 – 17 – sequence of installation of contour trusses and covering slabs.

Since when installing the coating, a rolling conductor is used, which is moved only after curing the mortar and concrete, one span cell is taken as the installation section (Fig. 22, b).

Installation of the shell panels begins with the outer ones, based on the conductor and the contour truss, then the remaining shell panels are mounted (Fig. 22, G, d).

3.1.3.2. Technology for constructing buildings with domed roofs

Depending on the design solution, the installation of domes is carried out using a temporary support, a hinged method or in its entirety.

Spherical domes are erected in ring tiers from prefabricated reinforced concrete panels in a mounted way. Each of the ring tiers after complete assembly has static stability and load-bearing capacity and serves as the basis for the overlying tier. Prefabricated reinforced concrete domes of indoor markets are installed in this way.

The panels are lifted by a tower crane located in the center of the building. Temporary fastening of the panels of each tier is carried out using an inventory device (Fig. 23, b) in the form of a stand with guys and a turnbuckle. The number of such devices depends on the number of panels in the ring of each tier.

Work is carried out from inventory scaffolding (Fig. 23, V), arranged outside the dome and moved during installation. Adjacent panels are connected to each other with bolts. The seams between the panels are sealed with cement mortar, which is first laid along the edges of the seam and then pumped into its internal cavity using a mortar pump. A reinforced concrete belt is placed along the upper edge of the panels of the assembled ring. After the mortar of the seams and the concrete of the belt acquire the required strength, the racks with guys are removed, and the installation cycle is repeated on the next tier.

Prefabricated domes are also mounted in a hinged manner by sequential assembly of ring belts using a movable metal truss template and racks with hangers for holding prefabricated slabs (Fig. 23, G). This method is used when installing prefabricated reinforced concrete circus domes.

To install the dome, a tower crane is installed in the center of the building. A mobile template truss is installed on the crane tower and the ring track located along the reinforced concrete cornice of the building. To ensure greater rigidity, the crane tower is braced with four braces. If the boom reach and lifting capacity of one crane are insufficient, a second crane is installed on the ring track near the building.

Prefabricated dome panels are installed in the following order. Each panel, in an inclined position corresponding to its design position in the coating, is lifted by a tower crane and installed with its lower corners on the inclined welded linings of the assembly, and with its upper corners on the installation screws of the template truss.

Rice. 23. Construction of buildings with domed coverings:

A– dome design; b– diagram of temporary fastening of dome panels; V– diagram of fastening the scaffolding for the construction of the dome; G– diagram of the dome installation using a mobile template truss; 1 – bottom support ring; 2 – panels; 3 – upper support ring; 4 – rack of inventory device; 5 – guy; 6 – turnbuckle; 7 – mounted panel; 8 – mounted panels; 9 – strut with holes to change the slope of the scaffold bracket; 10 – rack for railings; 11 – bracket crossbar; 12 – eye for attaching the bracket to the panel; 13 – mounting racks; 14 – strut braces; 15 – hangers for holding slabs; 16 – template truss; 17 – crane braces; 18 – panel truck

Next, the upper edges of the embedded parts of the upper corners of the panel are aligned, after which the slings are removed, the panel is secured with hangers to the mounting posts, and the hangers are tensioned using turnbuckles. The template truss set screws are then lowered by 100 - 150 mm and the template truss is moved to a new position for installation of the adjacent panel. After installing all the belt panels and welding the joints, the joints are sealed with concrete.

The next dome belt is installed after the concrete joints of the underlying belt have acquired the required strength. Upon completion of installation of the upper belt, remove the pendants from the panels of the underlying belt.

In construction, they also use the method of lifting concrete floors with a diameter of 62 m in their entirety using a system of jacks mounted on columns.

3.1.3.3. Technology for constructing buildings with cable-stayed roofs

The most critical process in the construction of such buildings is the installation of coverings. The composition and sequence of installation of cable-stayed coverings depends on their structural design. The leading and most complex process in this case is the installation of the cable-stayed network.

The structure of the suspended roof with a cable system consists of a monolithic reinforced concrete support contour; fixed on the supporting contour of the cable-stayed network; prefabricated reinforced concrete slabs laid on a cable-stayed network.

After the design tension of the cable-stayed network and grouting of the seams between the slabs and cables, the shell works as a single monolithic structure.

The cable network consists of a system of longitudinal and transverse cables located along the main directions of the shell surface at right angles to each other. In the support contour, the cables are secured using anchors consisting of sleeves and wedges, with the help of which the ends of each cable are crimped.

The cable-stayed shell network is installed in the following sequence. Each cable is installed in place using a crane in two steps. First, with the help of a crane, one end of it, removed from the drum by a traverse, is fed to the installation site. The cable anchor is pulled through the embedded part in the support contour, then the remaining part of the cable on the drum is secured and rolled out. After this, two cranes are used to lift the cable to the level of the support contour, while simultaneously pulling the second anchor to the support contour with a winch (Fig. 24, A). The anchor is pulled through the embedded part in the support contour and secured with a nut and washer. The cables are lifted together with special hangers and control weights for subsequent geodetic alignment.

Rice. 24. Construction of a building with cable-stayed roofing:

A– diagram of lifting the working cable; b– diagram of mutually perpendicular symmetrical tension of cables; V– alignment diagram of longitudinal cables; G– details of the final fastening of the cables; 1 – electric winch; 2 – guy; 3 – monolithic reinforced concrete support contour; 4 – lifted cable; 5 – traverse; 6 – level

Upon completion of the installation of the longitudinal cables and their pre-tensioning to a force of 29.420 - 49.033 kN (3 - 5 tf), a geodetic verification of their position is performed by determining the coordinates of the points of the cable network. Tables are drawn up in advance in which, for each cable, the distance of the control weight attachment points on the anchor sleeve from the reference point is indicated. At these points, test weights weighing 500 kg are suspended from a wire. The lengths of the pendants are different and calculated in advance.

When the working cables sag correctly, the control weights (risks on them) should be at the same mark.

After adjusting the position of the longitudinal cables, the transverse cables are installed. The places where they intersect with the working cables are secured with constant compression. At the same time, temporary guy wires are installed to secure the position of the cable-stay intersection points. Then the cable network surface is re-checked for compliance with the design. The cable-stayed network is then tensioned in three stages using 100-ton hydraulic jacks and traverses attached to sleeve anchors.

The tension sequence is determined from the conditions of tension of the cables in groups, simultaneous tension of the groups in the perpendicular direction, and symmetry of the tension of the groups relative to the axis of the building.

At the end of the second stage of tension, i.e. When the forces determined by the project are achieved, prefabricated reinforced concrete slabs are laid on the cable-stayed network in the direction from the lower mark to the upper one. In this case, formwork is installed on the slabs before they are lifted to seal the seams.

3.1.3.4. Technology of construction of buildings with membrane coatings

TO metal hanging coatings include thin-sheet membranes that combine load-bearing and enclosing functions.

The advantages of membrane coatings are their high manufacturability and installation, as well as the nature of the coating’s operation in biaxial tension, which makes it possible to cover 200-meter spans with a steel membrane only 2 mm thick.

Hanging tensile elements are usually secured to rigid supporting structures, which can be in the form of a closed contour (ring, oval, rectangle) resting on columns.

Let's consider the technology of installing a membrane coating using the example of the coating of the Olimpiysky sports complex in Moscow.

Sports complex"Olympic" is designed as a spatial structure of an elliptical shape 183×224 m. Along the outer contour of the ellipse, with a step of 20 m, there are 32 steel lattice columns, rigidly connected to the outer support ring (section 5×1.75 m). A membrane covering is suspended from the outer ring - a shell with a sag of 12 m. The covering has 64 stabilizing trusses, 2.5 m high, radially located with a step along the outer contour of 10 m, connected by ring elements - girders. The membrane petals were fastened to each other and to the radial elements of the “bed” with high-strength bolts. In the center, the membrane is closed by an internal metal ring of an elliptical shape measuring 24x30 m. The membrane covering was attached to the outer and inner rings with high-strength bolts and welding.

The installation of the membrane covering elements was carried out in large spatial blocks using a BK-1000 tower crane and two installation beams (with a lifting capacity of 50 tons), moving along the outer support ring. Along the long axis, two blocks were assembled simultaneously on two stands.

All 64 stabilizing coating trusses were united in pairs into 32 blocks of nine standard sizes. One such block consisted of two radial stabilizing trusses, girders along the upper and lower chords, vertical and horizontal connections. Pipelines for ventilation and air conditioning systems were installed in the unit. The mass of assembled stabilizing truss blocks reached 43 tons.

The covering blocks were lifted using a spreader beam, which absorbed the thrust force from the stabilizing trusses (Fig. 25).

Before lifting the truss blocks, they pre-stressed the upper chord of each truss with a force of about 1300 kN (210 MPa) and secured them with this force to the support rings of the coating.

The installation of prestressed blocks was carried out in stages by symmetrically installing several blocks along radii of the same diameter. After the installation of eight symmetrically installed blocks along with traverse spacers, they were simultaneously untwisted with the transmission of thrust forces evenly to the outer and inner rings.

The block of stabilizing trusses was lifted using a BK-1000 crane and an installer approximately 1 m above the outer ring. Then the chevre was moved to the installation site of this block. The block was unslinged only after it had been fully secured to the inner and outer rings as designed.

The membrane shell weighing 1569 tons consisted of 64 sector petals. The membrane petals were installed after the installation of the stabilization system was completed and secured with high-strength bolts with a diameter of 24 mm.

The membrane panels arrived at the installation site in the form of rolls. Rolling racks were located at the site where the stabilizing trusses were assembled.

Rice. 25. Scheme of installation of coating with enlarged blocks:

A– plan; b- incision; 1 – chevre-installer; 2 – stand for larger assembly of blocks; 3 – traverse-spacer for lifting the block and prestressing the upper chords of the trusses using a lever device (5); 4 – enlarged block; 6 – installation crane BK – 1000; 7 – central support ring; 8 – central temporary support; I – V – sequence of installation of blocks and dismantling of traverse struts

The installation of the petals was carried out in the sequence of installation of the stabilizing trusses. The tension of the membrane petals was carried out by two hydraulic jacks with a force of 250 kN each.

In parallel with laying and tensioning the membrane petals, holes were drilled and installed high strength bolts(97 thousand holes with a diameter of 27 mm). After assembly and design fastening of all elements of the coating, it was untwisted, i.e. release of the central support and smooth inclusion of the entire spatial structure into operation.

Planar structures

A

LECTURE 7. STRUCTURAL SYSTEMS AND STRUCTURAL ELEMENTS OF INDUSTRIAL BUILDINGS

Frames industrial buildings

Steel frame of one-story buildings

The steel frame of one-story buildings consists of the same elements as reinforced concrete (Fig.)

Rice. Steel frame building

There are two main parts in steel columns: the rod (branch) and the base (shoe) (Fig. 73).

Rice. 73. Steel columns.

A– constant cross-section with console; b– separate type.

1 – crane part of the column; 2 – supracolumn, 3 – additional height of the supracolumn; 4 – tent branch; 5 – crane branch; 6 – shoe; 7 – crane beam; 8 – crane rail; 9 – covering truss.

Shoes serve to transfer the load from the column to the foundation. Shoes and lower parts of columns in contact with the ground are concreted to prevent corrosion. To support the walls, prefabricated reinforced concrete foundation beams are installed between the foundations of the outer columns.

Steel crane beams can be solid or lattice. The most widely used are solid crane beams having an I-section: asymmetrical, used with a column spacing of 6 meters, or symmetrical with a column spacing of 12 meters.

The main load-bearing structures of coatings in buildings with steel frame are roof trusses(Fig. 74).

Rice. 74. Steel trusses:

A– with parallel belts; b- Same; V– triangular; G– polygonal;

d – polygonal truss design.

In outline they can be with parallel belts, triangular, polygonal.

Trusses with parallel belts are used in buildings with flat roofs, and also as rafters.

Triangular trusses are used in buildings with roofs that require large slopes, for example, made of asbestos-cement sheets.

The rigidity of the steel frame and its perception of wind loads and inertial influences from cranes is ensured by the arrangement of connections. Between the columns in longitudinal rows, vertical connections are placed - cross or portal. Horizontal transverse ties are placed in the planes of the upper and lower chords, and vertical ones - along the axes of the support posts and in one or more planes in the middle of the span.

Expansion joints

IN frame buildings expansion joints divide the building frame and all structures resting on it into separate sections. There are transverse and longitudinal seams.

Transverse expansion joints are installed on paired columns that support the structures of adjacent sections of the building cut by the joint. If the seam is also sedimentary, then it is also installed in the foundations of paired columns.

IN one-story buildings the axis of the transverse expansion joint is aligned with the transverse alignment axis of the row. Expansion joints in the floors of multi-story buildings are also solved.

Longitudinal expansion joints in buildings with a reinforced concrete frame are made on two longitudinal rows of columns, and in buildings with a steel frame - on one row of columns.

Walls of industrial buildings

In buildings without frames or with an incomplete frame, the outer walls are load-bearing and are made of brick, large blocks or other stones. In buildings with a full frame, the walls are made of the same materials, self-supporting on foundation beams or panel - self-supporting or hinged. External walls are located with outside columns, the internal walls of buildings rest on foundation beams or strip foundations.

In frame buildings with a significant length and height of the walls, to ensure stability between the elements of the main frame, additional racks are introduced, sometimes crossbars, forming an auxiliary frame called half-timbered.

For external drainage from coatings, the longitudinal walls of industrial buildings are made with cornices, and the end walls are made with parapet walls. With internal drainage, parapets are erected along the entire perimeter of the building.

Walls made of large panels

Reinforced concrete ribbed panels are intended for unheated buildings and buildings with large industrial heat releases. Wall thickness 30 millimeters.

Panels for heated buildings use reinforced concrete insulated or lightweight cellular concrete. Reinforced concrete insulated panels have a thickness of 280 and 300 millimeters.

The panels are divided into ordinary (for blank walls), lintel panels (for installation above and below window openings) and parapet panels.

In Fig. 79 shows a fragment of a wall of a frame panel building with strip glazing.

Rice. 79. Fragment of a wall made of large panels

The filling of window openings in panel buildings is carried out mainly in the form of strip glazing. The height of the openings is taken to be a multiple of 1.2 meters, the width is equal to the pitch of the wall columns.

For individual window openings of smaller width, wall panels with dimensions of 0.75, 1.5, 3.0 meters are used in accordance with the dimensions of standard frames.

Windows, doors, gates, lanterns

Lanterns

To provide lighting for workplaces located far from windows and for aeration (ventilation) of premises, lanterns are installed in industrial buildings.

Lanterns come in light, aeration and mixed types:

Lights with solid glazed frames, serving only to illuminate rooms;

Light-aeration with opening glazed doors, used for lighting and ventilation of rooms;

Aeration without glazing, used only for aeration purposes.

Lanterns can be of various profiles with vertical, inclined or horizontal glazing.

The profile of the lanterns is rectangular with vertical glazing, trapezoidal and triangular with inclined glazing, jagged with one-sided vertical glazing. In industrial construction, rectangular lanterns are usually used. (Fig. 83).

Rice. 83. Basic schemes of light and light-aeration lanterns:

A– rectangular; b– trapezoidal; V– toothed; G– triangular.

Based on their location relative to the axis of the building, lanterns are distinguished between longitudinal and transverse. Longitudinal lights are the most widespread.

Water drainage from lanterns can be external or internal. External is used for lanterns 6 meters wide or when there is no internal drainage system in the building.

The design of the lanterns is framed and consists of a number of transverse frames resting on the upper chords of trusses or roof beams, and a system of longitudinal bracings. The design diagrams of the lamps and their parameters are unified. For spans of 12, 15, and 18 meters, lanterns with a width of 6 meters are used, for spans of 24, 30 and 36 meters - 12 meters wide. The lantern fence consists of a covering, side and end walls.

Lantern covers are made of steel with a length of 6000 millimeters and a height of 1250, 1500 and 1750 millimeters. The bindings are glazed with reinforced or window glass.

Aeration is called natural, controlled and regulated air exchange.

The action of aeration is based on:

On thermal pressure arising due to the difference in temperature between indoor and outdoor air;

At the height difference (difference between the centers of the exhaust and supply openings);

Due to the action of the wind, which blows around the building, it creates a rarefaction of air on the leeward side (Fig. 84).

Rice. 84. Building aeration schemes:

A– the effect of aeration in the absence of wind; b- the same with the action of wind.

The disadvantage of light-aeration lanterns is the need to close the covers on the windward side, since the wind can blow polluted air back into the work area.

Doors and gates

Doors of industrial buildings do not differ in design from panel doors civil buildings.

The gates are intended to allow vehicles to enter the building and large masses of people to pass through.

The dimensions of the gate are determined in accordance with the dimensions of the equipment being transported. They must exceed the dimensions of the loaded rolling stock in width by 0.5-1.0 meters, and in height by 0.2-0.5 meters.

According to the method of opening, gates can be swing, sliding, lifting, curtain, etc.

Swing gates consist of two panels, hung by means of hinges in the gate frame (Fig. 81). The frame can be wooden, steel or reinforced concrete.

Rice. 81. Swing gates:

1 – pillars of the reinforced concrete frame framing the opening; 2 – crossbar.

If there is no space for opening the doors, the gates are made sliding. Sliding gates come in single-leaf and double-leaf types. Their door leaves have a design similar to swing doors, but in the upper part they are equipped with steel rollers, which, when opening and closing the gate, move along a rail attached to the crossbar of the reinforced concrete frame.

The lifting gate leaves are all-metal, suspended on cables and move along vertical guides.

The panel of curtain doors consists of horizontal elements that form a steel curtain, which, when lifted, is screwed onto a rotating drum located horizontally above the top of the opening.

Coatings

In one-story industrial buildings, the coverings are made without an attic, consisting of the main load-bearing elements of the covering and fencing.

In unheated buildings and buildings with excessive industrial heat generation, the enclosing structures of the coatings are made uninsulated, in heated buildings - insulated.

The cold roof structure consists of a base (flooring) and a roof. The insulated coating includes a vapor barrier and insulation.

Flooring elements are divided into small-sized (1.5 - 3.0 meters long) and large-sized (6 and 12 meters long).

In fencing made of small-sized elements, it becomes necessary to use purlins, which are placed along the building along beams or covering trusses.

Large-sized floorings are laid along the main load-bearing elements and the coatings in this case are called non-run.

Floorings

Non-running reinforced concrete decks are made of prestressed reinforced concrete ribbed slabs 1.5 and 3.0 meters wide and a length equal to the pitch of beams or trusses.

In non-insulated coverings, a cement screed is placed on top of the slabs, onto which the rolled roofing is glued.

In insulated coatings, low-thermal conductivity materials are used as insulation and additional vapor barrier is installed. Vapor barrier is especially necessary in coatings above rooms with high air humidity.

Small-size slabs can be reinforced concrete, reinforced cement or reinforced lightweight and cellular concrete.

Roll roofs are made of roofing material. A protective layer of gravel embedded in bitumen mastic is placed on the top layer of roll roofing.

Flooring made from leafy materials.

One of these floorings is galvanized steel profiled flooring, laid on purlins (with a truss spacing of 6 meters) or along lattice purlins (with a spacing of 12 meters).

Pitched cold coverings are often made from corrugated asbestos-cement sheets with a reinforced profile 8 millimeters thick.

In addition, sheets of corrugated fiberglass and other synthetic materials are used.

Drainage from coatings

Drainage extends the life of a building, protecting it from premature aging and destruction.

Drainage from the coatings of industrial buildings can be external and internal.

In one-story buildings, external drainage is arranged unorganized, and in multi-story buildings - with the use of drainpipes.

The internal drainage system consists of water intake funnels and a network of pipes located inside the building that drain water into the storm drain (Fig. 82).

Rice. 82. Internal drainage:

A– water intake funnel; b– cast iron pan;

1 – funnel body; 2 – cover; 3 – pipe; 4 – pipe collar; 5 – cast iron pan; 6 – hole for the pipe; 7 – burlap impregnated with bitumen; 8 - roll roofing; 9 – filling with molten bitumen; 10 - reinforced concrete slab coverings.

Internal drainage is arranged:

In multi-span buildings with multi-pitched roofs;

In buildings with large heights or significant differences in height of individual spans;

in buildings with large industrial heat releases, causing snow to melt on the surface.

Floors

Floors in industrial buildings are selected taking into account the nature of production impacts on them and the operational requirements placed on them.

Such requirements may be: heat resistance, chemical resistance, water and gas impermeability, dielectricity, non-sparking upon impact, increased mechanical strength and others.

It is sometimes impossible to select floors that meet all the necessary requirements. In such cases, it is necessary to use different types of floors within the same room.

The floor structure consists of a covering (clothing) and an underlying layer (preparation). In addition, the floor structure may include layers for various purposes. The underlying layer absorbs the load transmitted to the floors through the coating and distributes it to the base.

The underlying layers are rigid (concrete, reinforced concrete, asphalt concrete) and non-rigid (sand, gravel, crushed stone).

When installing floors on interfloor floors, floor slabs serve as the base, and the underlying layer is either absent altogether, or its role is played by heat and sound insulating layers.

Ground floors used in warehouses and hot shops, where they may be subject to shock from falling heavy objects or come into contact with hot parts.

Stone floors used in warehouses where significant shock loads are possible, or in areas covered by tracked vehicles. These floors are durable, but cold and hard. Such floors are usually covered with paving stones (Fig. 85).

Rice. 85. Stone floors:

A– cobblestones; b– from large paving stones; V– from small paving stones;

1 – cobblestone; 2 – sand; 3 – paving stones; 4 – bitumen mastic; 5 – concrete.

Concrete and cement floors used in rooms where the floor may be subject to constant moisture or exposure mineral oils(Fig. 86).

Rice. 86. Concrete and cement floors:

1 – concrete or cement clothing; 2 – concrete underlying layer.

Asphalt and asphalt concrete floors have sufficient strength, water resistance, water resistance, elasticity, and are easy to repair (Fig. 87). The disadvantages of asphalt floors include their ability to soften when the temperature rises, as a result of which they are not suitable for hot workshops. Under the influence of prolonged concentrated loads, dents form in them.

Rice. 87. Asphalt and asphalt concrete floors:

1 – asphalt or asphalt concrete clothing; 2 – concrete underlying layer.

TO ceramic floors include clinker, brick and tile floors (Fig. 88). Such floors are highly resistant to high temperatures and are resistant to acids, alkalis and mineral oils. They are used in rooms that require great cleanliness, in the absence of shock loads.

Rice. 88. Ceramic tile floors:

1 – ceramic tiles; 2 – cement mortar; 3 – concrete.

Metal floors used only in certain areas where the floors are touched by hot objects and at the same time a flat, hard surface is needed and in workshops with strong shock loads (Fig. 89).

Rice. 89. Metal floors:

1 – cast iron tiles; 2 – sand; 3 – soil base.

Floors can also be used in industrial buildings planks and from synthetic materials. Such floors are used in laboratories, engineering buildings, and administrative premises.

In floors with a rigid underlying layer, expansion joints are installed to avoid cracks. They are arranged along the lines expansion joints buildings and in places where different types of floors meet.

To lay utility lines, channels are installed in the floors.

The junction of floors to walls, columns and machine foundations is made with gaps for free settlement.

In wet rooms, to drain liquids, the floors are given a relief with slopes towards cast iron or concrete water intakes, which are called ladders. The drains are connected to the sewerage system. Along the walls and columns it is necessary to install skirting boards and fillets.

Stairs

Staircases of industrial buildings are divided into the following types:

- basic, used in multi-storey buildings for permanent communication between floors and for evacuation;

- official, leading to work sites and mezzanines;

- fire extinguishers, mandatory for building heights of more than 10 meters and intended for fire brigade members to climb onto the roof (Fig. 90).

Rice. 90. Fire escape

- emergency external, arranged for the evacuation of people when there is an insufficient number of main stairs (Fig. 91);

Rice. 91. Emergency ladder

Fire barriers

Classification of buildings and premises according to explosion and fire hazard is used to establish fire safety requirements aimed at preventing the possibility of a fire and ensuring fire protection people and property in case of fire. According to explosion and fire hazard, premises are divided into categories A, B, B1-B4, D and D, and buildings into categories A, B, C, D and D.

Categories of premises and buildings are determined based on the type of flammable substances and materials located in the premises, their quantity and fire hazardous properties, as well as based on the space-planning solutions of the premises and the characteristics of the technological processes carried out in them.

Fire barriers are installed to prevent fire from spreading throughout the building in the event of a fire. Fireproof floors serve as horizontal barriers in multi-storey buildings. Vertical barriers are fire walls (firewalls).

Firewall is intended to prevent the spread of fire from one room or building to an adjacent room or building. Firewalls are made of fireproof materials - stone, concrete or reinforced concrete, and must have a fire resistance rating of at least four hours. Firewalls must rest on foundations. Firewalls are made to cover the entire height of the building, separating combustible and non-combustible coverings, ceilings, lanterns and other structures and must rise above combustible roofs by at least 60 centimeters, and above non-combustible roofs by 30 centimeters. Doors, gates, windows, manhole covers and other fillings of openings in firewalls must be fireproof with a fire resistance rating of at least 1.5 hours. Firewalls are designed for stability in the event of a one-sided collapse of floors, coverings and other structures during a fire (Fig. 92).

Rice. 92. Firewalls:

A– in a building with fireproof external walls; b– in a building with combustible or non-combustible external walls; 1 – firewall ridge; 2 – end firewall.

Control questions

1. Name the design diagrams of industrial buildings.

2. Name the main types of frames for industrial buildings.

3. What types of walls are there in industrial buildings?

LECTURE 8. STRUCTURAL SYSTEMS AND STRUCTURAL ELEMENTS OF AGRICULTURAL BUILDINGS AND STRUCTURES

Greenhouses and greenhouses

Greenhouses and hotbeds are glazed structures in which the necessary climatic and soil conditions are artificially created to allow the cultivation of early vegetables, seedlings and flowers.

Greenhouse buildings are constructed primarily from prefabricated reinforced concrete glazed panels, fastened together by welding embedded parts.

The greenhouse structure consists of prefabricated reinforced concrete frames installed in the ground along the length of the greenhouse and prefabricated reinforced concrete frames (longitudinal bed of the greenhouse) laid on the frame consoles. Removable glazed greenhouse frames are made of wood (Fig. 94).

Rice. 94. Greenhouse made of prefabricated reinforced concrete elements:

1 – reinforced concrete frames; 2 – reinforced concrete northern log; 3 – the same, southern;

4 – sand; 5 – nutrient layer of soil; 6 – heating pipes in a layer of sand;

7 – glazed wooden frame.

LIST OF REFERENCES USED

1. Maklakova T. G., Nanasova S. M. Constructions of civil buildings: Textbook. – M.: ASV Publishing House, 2010. – 296 p.

2. Budasov B.V., Georgievsky O. V., Kaminsky V. P. Construction drawing. Textbook for universities / Under general. ed. O. V. Georgievsky. – M.: Stroyizdat, 2002. – 456 p.

3. Lomakin V. A. Fundamentals of construction. – M.: Higher School, 1976. – 285 p.

4. Krasensky V.E., Fedorovsky L.E. Civil, industrial and agricultural buildings. – M.: Stroyizdat, 1972, – 367 p.

5. Koroev Yu. I Drawing for builders: Textbook. for prof. Textbook establishments. – 6th ed., erased. – M.: Higher. school, ed. Center "Academy", 2000 – 256 p.

6. Chicherin I. I. Civil works: a textbook for beginners. prof. Education. – 6th ed., erased. – M.: Publishing Center “Academy”, 2008. – 416 p.

LECTURE 6. STRUCTURES OF LONG-SPAN BUILDINGS WITH SPATIAL COVERINGS

Depending on the structural design and static operation, load-bearing structures of coatings can be divided into planar (working in the same plane) and spatial.

Planar structures

This group of load-bearing structures includes beams, trusses, frames and arches. They can be made of prefabricated and monolithic reinforced concrete, as well as metal or wood.

Beams and trusses together with columns form a system of transverse frames, the longitudinal connection between which is carried out by covering slabs and wind braces.

Along with prefabricated frames, in a number of unique buildings with increased loads and large spans, monolithic reinforced concrete or metal frames are used (Fig. 48).

Rice. 48. Long-span structures:

A- monolithic reinforced concrete frame, double-hinged.

To cover spans over 40 meters, it is advisable to use arched structures. Arches can be structurally divided into two-hinged (with hinges on the supports), three-hinged (with hinges on the supports and in the middle of the span) and hingeless.

The arch works mainly in compression and transfers not only vertical load, but also horizontal pressure (thrust) to the supports.

Compared to beams, trusses and frames, arches have less weight and are more economical in terms of material consumption. Arches are used in structures in combination with vaults and shells.

Modern engineering and construction technologies allow the construction of unique long-span structures and spatial structures that have distances between load-bearing supports of more than 40 meters, making them reliable and functional. Most often these are factory machine-building and shipbuilding workshops, hangars, parking lots, stadiums, station buildings, theaters and galleries.

Long-span metal structures have elasticity and allow you to create various types of interfaces for constructing expressive geometric shapes and architectural solutions of any complexity. Moreover, they contain many stress concentrators. Correct and uniform distribution of high load-bearing loads between structural elements is important, since dangerous damage can occur under the influence of the natural gravity of the structure and the wobbling of external factors.

Structures based on long-span beams are at particular risk of developing deformations and cracks during construction and during operation, which subsequently lead to destruction. Therefore, they require constant real-time monitoring and monitoring of their condition to ensure safety conditions.

Typical reasons that cause problems in long-span buildings:

• poorly conducted geophysical and geodetic surveys, replacement of experimental calculations with modeling;
• design errors, miscalculations in determining loads and locations of geometric centers, displacement of axes, violation of the principles of straightness or rigidity of elements;
• violation of manufacturing technologies or rules for installation of structures, incorrect node connections, use of unsuitable building materials (for example, choosing a type of steel unsuitable for specific conditions);
• uneven sedimentary processes affecting the stability and integrity of foundations, supporting elements, vaults and ceilings;
• improper operation, abnormal loads and emergency impacts;
• temporary wear and tear;
• the influence of unfavorable natural factors (wind pressure, displacement of soil layers and movement groundwater, seismic processes, temperature and humidity conditions in which rusting of metal structural elements, destruction of concrete, etc. occurs);
• vibrations created by traffic and nearby construction work.

As a result of the influence of these factors and causes, deformations of the main supports and loss of their load-bearing capabilities, deflections and displacements of span beams, and progressive destruction occur. This creates a danger to human life and leads to economic losses associated with the need to compensate for damage from accidents and carry out repairs.

Object condition monitoring

Monitoring of long-span buildings and structures allows you to track physical wear and tear and decrease in load-bearing capacity engineering structures, identify unfavorable changes, the appearance of defects and damage, detect dangerous stress-strain states, monitor their exceedance of the limit values ​​provided for by the project, timely notice exceeding the established reliability coefficients and maximum permissible deviations of the observed parameters.

Monitoring is carried out using special high-precision measuring instruments, control devices, recorders significant parameters and reliability indicators that capture electromagnetic and ultrasonic vibrations, sensors and geodetic markers, computerized dispatch consoles, automatic equipment And signaling systems alerts.
Long-span buildings are equipped with engineering monitoring and control systems, which are informationally linked with the duty and dispatch services of the Ministry of Emergency Situations. Such systems make it possible to collect data simultaneously from many transmitters and according to different parameters. This information flows into a single center, is integrated, analyzed using specified algorithms, and ultimately produces a schematic and visually presented result indicating the state of the structure under study.

Based on this, monitoring specialists can draw up conclusions, forecasts and reports with reasonable diagnostics of objects, recommendations and programs of effective measures to eliminate existing defects and destabilizing factors, minimize risks and threats of occurrence emergency situations, their avoidance and prevention of damage. In the event of emergencies and emergency situations, rescue services are promptly informed about them.

Specialists in engineering and construction monitoring

SMIS Expert company develops system solutions to conduct vulnerability assessments and diagnose problems in long-span structures, monitoring support for the construction and operation of buildings for various purposes. We have extensive experience and highly qualified specialists. We use modern scientific knowledge and innovative technologies. We provide professional geodetic monitoring and research of all types of objects to determine the degree of their reliability, safety and durability. We sell high-precision measuring equipment and instruments.

Long-span structures play a significant role in world architecture. And this was laid down in ancient times, when this special direction of architectural design actually appeared.

The idea and implementation of long-span projects is inextricably linked with the main desire of not only the builder and architect, but of all humanity as a whole - the desire to conquer space. That is why, starting from 125 AD. e., when the first long-span structure known in history, the Pantheon of Rome (base diameter - 43 m), appeared, and ending with the creations of modern architects, long-span structures are especially popular.

History of long-span structures

As mentioned above, the first was the Pantheon in Rome, built in 125 AD. e. Later, other majestic buildings with large-span domed elements appeared. A striking example is the Church of Hagia Sophia, built in Constantinople in 537 AD. e. The diameter of the dome is 32 meters, and it itself gives the entire structure not only majesty, but also amazing beauty, which is admired by both tourists and architects to this day.

In those and later times it was impossible to build light structures from stone. Therefore, domed structures were characterized by great massiveness and their construction required serious time expenditure - up to a hundred years or more.

Later, for arranging the floors of large spans, they began to use wooden structures. Here shining example is an achievement of domestic architecture - the former Manege in Moscow was built in 1812 and had wooden spans 30 m long in its design.

The 18th-19th centuries were characterized by the development of ferrous metallurgy, which gave new and more durable materials for construction - steel and cast iron. This marked the advent of long-span aircraft in the second half of the 19th century. steel structures who received great application in Russian and world architecture.

The next building material that significantly expanded the capabilities of architects was reinforced concrete structures. Thanks to the emergence and improvement of reinforced concrete structures, the world architecture of the 20th century was replenished with thin-walled spatial structures. At the same time, in the second half of the twentieth century, suspended coverings, rod and pneumatic systems began to be widely used.

In the second half of the twentieth century, there appeared laminated wood. The development of this technology has made it possible to “bring back to life” wooden long-span structures, to achieve special indicators of lightness and weightlessness, to conquer space, without compromising on strength and reliability.

Long-span structures in the modern world

As history shows, the logic of the development of long-span structural systems was aimed at improving the quality and reliability of construction, as well as the architectural value of the structure. The use of this type of structure made it possible to make the most of the full potential of the load-bearing properties of the material, thereby creating lightweight, reliable and economical floors. All this is especially important for a modern architect, when the modern construction reduction in the mass of structures and structures has been promoted.

But what are long-span structures? Here expert opinions differ. There is no single definition. According to one version, this is any structure with a span length of more than 36 m. According to another, structures with an unsupported covering more than 60 m long, although they are already classified as unique. The latter also include buildings with a span of more than one hundred meters.

But in any case, regardless of the definition, modern architecture It is clear that long-span structures are complex objects. And this means high level responsibility of the architect, the need to take additional safety measures at each stage - architectural design, construction, operation.

An important point is the choice of building material - wood, reinforced concrete concrete or steel. In addition to these traditional materials, special fabrics, cables and carbon fiber are also used. The choice of material depends on the tasks facing the architect and the specifics of construction. Let's consider the main materials used in modern long-span construction.

Prospects for long-span construction

Taking into account the history of world architecture and the inevitable desire of man to conquer space and create perfect architectural forms, we can safely predict a steady increase in attention to long-span structures. As for materials, in addition to modern high-tech solutions, increasing attention will be paid to FCC, which is a unique synthesis of traditional material and modern high technology.

As for Russia, given the pace of economic development and the unmet need for facilities for various purposes, including trade and sports infrastructure, the volume of construction of long-span buildings and structures will constantly increase. And here unique design solutions, quality of materials and the use of innovative technologies will play an increasingly important role.

But let's not forget about the economic component. It is this that stands and will stand at the forefront, and it is through it that the effectiveness of a particular material, technology and design solution will be considered. And in this regard, I would again like to remember about laminated wood structures. According to many experts, they hold the future of long-span construction.

Question 59. Constructive decisions long-span systems. Loads acting on long-span structures. Layout of frames for long-span coverings

The frames of long-span roofs with beam and frame load-bearing systems have a layout scheme close to the frames of industrial buildings. For large spans and the absence of crane beams, it is advisable to increase the distances between the main load-bearing structures to 12-18 m. The systems of vertical and horizontal connections have the same purposes as in industrial buildings and are arranged in a similar way.

The layout of frame coverings can be transverse when load-bearing frames are placed across the building, and longitudinal, typical for hangars. With a longitudinal layout, the main supporting frame is placed in the direction of the larger dimension of the building plan and the transverse trusses rest on it.

The upper and lower chords of the supporting frames and transverse trusses are untied with cross braces, ensuring their stability.

In arched systems, the pitch of the arches is 12 m or more; The main purlins are laid along the arches, on which the transverse ribs supporting the roof deck rest.

For large spans and heights of the main load-bearing systems (frames, arches), spatially stable block structures are used by pairing adjacent flat frames or arches (Fig. 8), as well as by using triangular sections of arches. The arches are connected in the key by longitudinal connections, the importance of which for the rigidity of the structure is especially great when the lifting boom of the arches is large, when their overall deformability increases.

The transverse braces located between the outer pair of arches are calculated on the wind pressure transmitted from the end wall of the arched covering.

QUESTION 60. Long-span beam structures. Their advantages and disadvantages. Constructive decisions. Loads acting on beam structures. Fundamentals of calculation and design of beam structures.

Beam structures

Long-span beam structures are used in cases where supports cannot withstand thrust forces.

Beam systems for large spans are heavier than frame or arch systems, but are easier to manufacture and install.

Beam systems are used mainly in public buildings - theaters, concert halls, sports facilities.

The main load-bearing elements of beam systems used for spans of 50-70 m or more are trusses; Solid beams with large spans are unprofitable in terms of metal consumption.

Main advantages beam structures are characterized by precise operation, absence of thrust forces and insensitivity to support settlements. Main disadvantage– relatively high consumption of steel and high height, caused by large flying moments and rigidity requirements.

Rice. 1, 2, 3

The cross-sections of the rods of long-span trusses with forces in the rods exceeding 4000-5000 kN are usually taken to be composite of welded I-beams or rolled sections.

The high height of the trusses does not allow them to be transported by rail in the form of assembled shipping elements, so they are supplied for installation in bulk and consolidated on site.

The elements are connected by welding or high-strength bolts. High-precision bolts and rivets should not be used because they are labor intensive.

Long-span trusses are calculated and their sections are selected in the same way as light trusses of industrial buildings.

Due to large support reactions, it becomes necessary to transmit them strictly along the axis of the truss unit, otherwise significant additional stresses may arise.

For spans of 60-90m, the mutual displacement of the supports becomes significant due to the deflection of the truss and its temperature deformations. In this case, one of the supports can be a roller (Fig. 6), allowing free horizontal movements.

If the trusses are installed on high flexible columns, then even with spans of up to 90 m, both supports can be stationary due to the flexibility of the upper parts of the columns.

Long-span beam systems can consist of triangular trusses with prestressing, which are convenient to manufacture, transport and install (Fig. 7).

Inclusion in working together for compression of a reinforced concrete slab laid along the upper chords of the truss, the use of tubular rods and prestressing make such trusses economical in terms of metal consumption.

Steel sheets are included in the design sections of the upper and lower chords of the trusses.

In order for a thin sheet to work under compression, a preliminary tensile stress is created in it that is greater than the compressive stress from the load.

QUESTION 61. Frame long-span structures. Their advantages and disadvantages. Constructive decisions. Loads acting on frame structures. Fundamentals of calculation and design of frame structures.

Frame structures

Frames covering large spans, can be double-hinged or hingeless.

Hingeless frames are more rigid, more economical in metal consumption and more convenient to install; however, they require more massive foundations with dense bases for them and are more sensitive to temperature influences and uneven settlements of the supports.

Frame structures, compared to beam structures, are more economical in terms of metal consumption and are more rigid, due to which the height of the frame crossbar is lower than the height of beam trusses.

In long-span coverings, both continuous and through frames are used.

Solid frames are rarely used for small spans (50-60 m), their advantages: less labor intensity, transportability and the ability to reduce the height of the room.

The most commonly used frames are hinged frames. It is recommended to take the height of the frame crossbar equal to: with through trusses 1/12-1/18 of the span, with solid crossbars 1/20 - 1/30 of the span.

Frames are calculated using structural mechanics methods. To simplify the calculations, lightweight through frames can be reduced to their equivalent solid frames.

Heavy through frames (such as heavy trusses) must be designed as lattice systems, taking into account the deformation of all lattice rods.

For large spans (more than 50 m) and low rigid posts, it is necessary to calculate the frames for temperature effects.

Crossbars and racks of solid frames have solid I-sections; their load-bearing capacity is checked using formulas for eccentrically compressed rods.

In order to simplify the calculation of lattice frames, their expansion can be determined as for a solid frame.

Using an approximate calculation, preliminary sections of the frame chords are established;

determine the moments of inertia of cross-sections of crossbars and racks using approximate formulas;

calculate the frame using methods structural mechanics; the design diagram of the frame should be taken along the geometric axes;

Having determined the support reactions, the calculated forces in all the rods are found, according to which their sections are finally selected.

The types of sections, design of nodes and connections of frame trusses are the same as for heavy trusses of beam structures.

Another artificial method of unloading the crossbar is the displacement of the supporting hinges in the double-hinged frame from the axis of the rack inward. In this case, vertical support reactions create additional moments that unload the crossbar.