Movable supports of metal long-span coverings. The buildings are long-span. Long-span structures in the modern world
Planar structures
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LECTURE 7. STRUCTURAL SYSTEMS AND STRUCTURAL ELEMENTS OF INDUSTRIAL BUILDINGS
Frames of 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 roofs in buildings with a 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 combined 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 on the outside of the columns, the internal walls of buildings are supported by 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 There are single-field and double-field. 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 the decks are made of reinforced concrete prestressed ribbed slabs with a width of 1.5 and 3.0 meters and a length equal to the pitch of the beams or trusses.
In non-insulated coverings, a cement strainer, on which the roll 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 coverings above rooms with high humidity air.
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 covering slab.
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 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 resist the action well high temperature, 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 hot objects touch the floors 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
Stairs 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 growing 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 design and static operation bearing structures coatings can be divided into planar (working in one 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 buildings of a unique nature, 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.
The atrium of one of the American hotels owned by Gaylord Hotels
the future comes from the present
and is determined by the path we choose today
Long-span translucent structures are becoming an integral part of urban architecture of the 21st century. The best architects today are increasingly creating amazing complexes of buildings, the center of attraction in which, a certain spatial core, is large atrium spaces - voluminous, filled with light and comfort, well protected from negative external influences and covered with reliable translucent coatings.
Further active development of such structures will probably be able in the near future not only to maximally expand the comfortable and safe space of the human environment, but will also make it possible in the future to change the appearance of our cities and improve their current condition.
Architecture of the era of globalization
At all times in their history, people have sought to protect and protect themselves from numerous unfavorable and dangerous influences from their environment. Heat and cold, rain and wind, predatory animals and wild people have always been a known problem for a quiet human life. Therefore, from ancient times, our ancestors began to build shelters for themselves, which, by creating an artificial environment protected from external influences, brought more of the desired comfort and safety into their lives. And the emerging architecture, as an amazing and excellent instrument of these creative human actions, from its very inception and at all stages of development, tried to make maximum use of the available technical capabilities and existing aesthetic views in society to better satisfy these important human needs: both in comfort and in security.
Today has come an era of unprecedented technological development, and in construction industry this made it possible to implement almost any, the most daring architectural ideas. In this regard, the main factors limiting the implementation of all significant projects of modern architects today are often no longer the lack of technical capabilities for the construction of a large and complex object, but only some of our subjective ideas about it, such as: the insufficient usefulness of the future structure, its low demand and low profitability, or the future construction time is too long and the selling price is high. At the same time, with the beginning of a boom in the implementation of the principles of “sustainable development” and “green building” throughout the world, the presence of the factor of environmental sustainability of buildings is also gaining more and more weight for their construction.
With wide technical opportunities opening up for the development of architecture of the 21st century, modern architects in their work, it seems, should begin to take more into account the significant impact that their projects have on the development of the urban environment. It is obvious that modern megacities, having become hostages of the past path of their development and the ongoing approach to their development, are gradually becoming more and more a multifactorial problem for the peace and safety of their residents.
Having entered the era of globalization, our world has changed greatly over last years, and today it is hardly possible to find reasonable justifications for the ongoing formation of crowded living of people in separate points of space. Our society is beginning to understand the destructiveness of this process, but urban architecture, unfortunately, still continues to follow the path of creating high-rise projects and densifying urban development, thereby provoking an even greater concentration of the population in certain points of an already excessively overpopulated space.
At the same time, having modern technologies and using its colossal impact on the life of society, the architecture of the 21st century can not only maximize the comfortable and safe space of the human environment, but also can and should try, step by step, to radically change the appearance of our cities and improve their current state. In addition, Architecture, as the unsurpassed master of space, time and the imagination of many people, will certainly increasingly contribute to the emergence of fundamentally new eco-cities and eco-villages.
City under the dome
The dream of translucent coatings that protect streets and city blocks from rain and snow originated with people a long time ago. But only with the advent of the industrial revolution, which brought broad technical and financial opportunities, the implementation of such projects becomes feasible. It was only during the second half of the 19th century that large glass-covered arcades with rows of expensive shops and cozy cafes appeared in most of the main cities of Europe and America. And one of the very first notable pearls of that period of development of large glazed atrium spaces is the famous Galleria Vittorio Emmanuel II in Milan, open to visitors back in 1877.
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Fig.2. Gallery of Victor Emmanuel II in Milan.
Since progress cannot be stopped, actively participating in it, and not remaining on the margins of history, is the task of all great countries. That is why, since the second half of the twentieth century, construction science in the USSR, the USA and some other countries has already been seriously working on the ability to protect their cities with large translucent domes from: undesirable weather phenomena, negative features of the local climate, excessive levels of solar radiation and other environmental influences unfavorable for humans. In recent years, the list of stimulating factors further research in this direction, we can add: rapid and unpredictable climate changes on the planet, an alarming increase in environmental pollution, growing threats of extremism, as well as the desire of people to reduce the extremely high energy costs of their cities.
Today, the creation of long-span translucent protective structures (hereinafter referred to as LSPS), in which there is a lot of natural light and comfort, has become more active than ever before. New ideas are emerging and a variety of unique projects are being created - such as the Dome over Houston - and some of these amazing projects are already being implemented. Thus, in Astana, with the help of English engineers and Turkish builders, a 100-meter (excluding the height of the spire) translucent tent was built, which housed the largest and most presentable shopping and entertainment center in Kazakhstan.
An even more amazing and grandiose structure was created in Germany - this is the Tropical Islands water entertainment center, which has an internal volume of about 5.5 million cubic meters. m and is rightfully the largest translucent building in the world by this indicator today.
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Fig.3-5. Water entertainment center "Tropical Islands" in Germany
An important stage in the development of volumetric translucent structures was the scientific substantiation of the possibility of their tangible efficiency - both in energy efficiency and in a significant reduction in heat loss, while simultaneously significantly expanding the newly created comfortable and in-demand public space.
The credit for this justification belongs to English and American architects and scientists, but, first of all, we can highlight the work of Terry Farrell and Rolf Lebens, who at the border of the 70-80s of the twentieth century created the concept of “buffer thinking”. The result of this concept was the active introduction of the “buffer effect” or the “double enclosure principle” into world architectural practice.
When researching the issue of the possibility of creating efficient large atrium spaces, warming, cooling and transformable types of atriums were identified. Only a little more than 30 years have passed since then, but even during this short period of time, modern atrium spaces have conquered the entire civilized architectural world (photos of American atriums given in this article are a small fraction of the existing multitude and variety of atrium spaces built over the years). Unfortunately, modern Russia, in this sense, does not yet have great achievements.
Agreeing with the existing arguments of experts, on the advisability of using in modern architecture large atrium spaces, and without trying to dispute their conclusions, the author of the article further proposes to consider the possibility of how, with the help of multi-belt cable structures, to create (cover) such spaces cheaper and more reliably, and also not be particularly limited by the size of atriums, introducing a new technology for covering large spans. It seems that in Russian conditions, even just the creation of the simplest second fence (buffer space) around city blocks will make it possible to wisely use those numerous heat losses of covered buildings, which will not be irretrievably dissolved in the surrounding space, but will provide heating for the resulting atrium spaces. Only due to a high-quality translucent protective coating, the temperature in such atrium spaces in winter can be 10-15 degrees higher than outside.
In the summer, in addition to reasonable, adjustable partial shading of the internal space, from excessive solar radiation and overheating, it is possible to provide for the opening of ventilation openings in the translucent covering, as well as to implement other known and effective methods creating a comfortable microclimate inside the entire translucent complex. Obviously, creating a comfortable and stable microclimate in one large enclosed space will be much easier and cheaper than providing the same comfortable conditions simultaneously in thousands of small rooms.
The very nature of volumetric translucent structures encourages us to discard some of the stereotypes of our thinking when solving such problems, and take a fresh look at the possibility of creating a comfortable environment in the new conditions of large volumetric spaces. At the same time, there are already new effective technical solutions that use the important advantages of large spaces and make it possible to provide stable comfortable conditions for the entire internal space of the BSZS at significantly lower energy costs.
Meanwhile, the possibilities for using multi-belt cable coverings seem to be wider. Thus, the process of building eco-cities, which is still in its infancy and timidly announces itself, also cannot be imagined without large-span translucent structures. I would like to think that the 21st century, having appreciated the new large-span translucent architecture, will actively develop and improve it, and will also try to use it to quickly make a breakthrough in urban planning, replacing the dull, energy-inefficient and unsafe concrete jungle of modern megacities with convenient, comfortable and environmentally friendly cities.
Rice. 6-11 Masdar City (illustrations by Foster + Partners). 
The most ambitious and pompous eco-city project today can be called Masdar City. This is probably the first truly serious attempt at an integrated approach to organizing the city of the future - powered by energy from renewable sources (sun, wind, etc.) and having a sustainable ecological environment with minimal emissions carbon dioxide into the atmosphere, as well as a system for the complete recycling of waste from urban activities.
Unfortunately, the location chosen for the construction of Masdar City was not the most successful, and future residents and operating organizations will still have to experience some of the inconveniences of the location of this corner of the desert. It is so obvious that the technical solutions included in the city project will not be able to fully cope with the 50-degree summer heat (the exception will be closed spaces, including all atriums). The rainy periods in December-January, and later the season of heavy fog, will also not be comfortable for the residents of the new city. And if we remember the fairly frequent winter-spring sandstorms in that part of the desert, we will understand that without large-span translucent coatings covering and protecting city blocks from these local natural phenomena, city residents will periodically have to experience certain inconveniences.
The concept proposed below for the construction of large-span translucent structures fits well into projects like Masdar City and, it seems, is quite capable of helping such projects save money on both the construction and operation of modern cities. And also to make these cities safer and more comfortable.
Figure 6-11. This is how the future Masdar City can be seen in colorful advertising brochures and magazine illustrations (illustrations by Foster + Partners).
In 2012, Russian engineers developed a concept for covering large spans that is technically accessible today and effective in implementation, allowing for the construction of a variety of large-span buildings and structures. The idea is to create a multi-belt cable covering over a complex of buildings, which, covering large spans between supporting buildings, will be able to carry any design load and create a single durable and reliable translucent covering for the entire complex. The coating will provide the ability to maintain constant and comfortable parameters for humans in the enclosed internal space of such an object: temperature, humidity, air mobility and cleanliness, illumination, safety, etc.
The idea of multi-belt cable systems is based on the well-known principles of suspended structures, which have been widely used in the world for the construction of long-span buildings and structures for more than half a century. But hanging structures have not become more widespread in long-span construction due to some of their shortcomings. Thus, large-span buildings with suspended roof structures, as a rule, cannot provide a slope of the roof to the outside of the building, which creates additional difficulties with the removal of precipitation from the roof. In addition, by creating very significant horizontal loads in high supports, cable-stayed structures force builders to solve this problem with additional financial investments in powerful buttresses for these loads. But the main disadvantage of hanging structures is their high deformability under the influence of local loads.
Multi-belt cable systems managed to overcome the listed disadvantages of long-span cable-stayed coverings and even created the opportunity to successfully cover much larger spans, which today can give a new impetus to the development of long-span construction.
It is known that the covering of large spans at all times of the development of our civilization interested and attracted the attention of not only architects and builders, but also ordinary people. The creation of majestic structures with large spans has always been an indicator of the advanced development of engineering, as well as the technical and financial power of countries capable of building such structures.
What is multi-belt rope covering and how does it work?
To understand how a multi-belt cable covering works, one must imagine the design of any known long-span covering that was used to block the span between two supporting buildings. (for example, spatial cross-bar slab). If the span is large enough, then this coating will inevitably bend under its own weight, and when exposed to additional external loads (from snow, wind, etc.) it may collapse. But to prevent this from happening long-span covering did not collapse, we pull high-strength steel cables under it in several rows (belts), from one supporting building to another, tension them and install (at certain distances along the length of the cables) between the belts of the resulting cable system, spacer posts, and between adjacent cables in all belts of the cable system - spacers and/or guy wires. Multi-banding helps ensure that at any span length the cable system is biconvex and supports the sagging covering in question from below.
At the same time, in the coating, due to the tension of the cables and the work of the spacer posts, not only will the resulting deflection disappear, but also a deflection will appear with the opposite sign - upward. This allows the coating not only not to collapse under the influence of extreme loads on it, but, on the contrary, will contribute to the possibility of it accepting significant additional loads, in accordance with the design characteristics of the cable system that will be assigned to it by the project.
Experts understand that a system of prestressed cable structures supporting a rigid, durable and stable coating is impossible without powerful support elements (receiving horizontal components from the thrust of the cable system), as well as a stabilizing system that absorbs all temporary loads on the coating, including negative wind pressure . Therefore, the proposed concept for the construction of BSZS takes into account all the conditions necessary for these structures.
So, in order to make the multi-belt cable covering unchangeable under the influence of temporary loads, it is additionally provided, with the help of guy ropes, to add additional load to the covering by the calculated value. At the same time, the covering guys are attached to the foundations of the supporting buildings, which avoids increasing the load on these foundations from the additional weight of the long-span covering caused by the tension of the guys.
As a result of the joint work of the multi-belt cable system and the glazed frame covering located on it, a single, lightweight and reliable long-span translucent cable covering was formed, which today is capable of covering spans of 200-350 meters or more.
It is clear that the roof covering, the basis of which is long-span multi-belt cable systems, can, if desired, be made from any hydro-thermal insulating material, including translucent. For example, in conditions of low ambient temperatures, the best translucent material today is multi-chamber double-glazed windows.
The advantages of multi-belt cable systems over the currently known technical solutions used to cover large spans are obvious. This is a very significant strength and reliability of such systems, excellent load bearing capacity, lightness of structures, the ability to cover significantly larger spans, better light transmittance of the coating, several times lower metal consumption of structures and, as a result, relatively low cost of the entire coating.
Application of multi-belt cable systems.
It should be noted that the technology of covering large and extra-large spans using multi-belt cable systems will make it possible to build structures of a wide variety of volumes, shapes and purposes. These can be: the largest hangars and production workshops, indoor athletics and football stadiums, long-span public spaces, entertainment and shopping centers, residential areas under a translucent shell, large glass pyramids and domes (which can accommodate a wide variety of multifunctional complexes real estate or corporate centers). Multi-lane cable systems can also be useful in the construction of new design long-span suspension bridges, especially in places where construction of other types of bridges is impossible or too expensive.
Fig. 12. A translucent structure in the form of a PYRAMID with a height of 200 m.
It seems that the construction of long-span translucent complexes should be developed as block development. And one of the most spectacular and optimal initial options for such a functional development can be, for example, the shape of a translucent block in the form of a regular quadrangular PYRAMID (Fig. 11) with the following parameters:
- height of the pyramid – 200 m;
- base dimensions - 300x300 m;
- base area (territory protected by translucent coatings) – 9.0 ha;
- area of enclosing structures - 150,000 m2;
- geometric volume of the pyramid (P200) - 6.0 million cubic meters.
In such a glazed quarter, in order not to overcrowd the internal space of the complex, it is reasonable to have only 320-450 thousand square meters of usable space (above ground), occupied by commercial and/or residential real estate and located mainly in the supporting buildings of this translucent complex. The remaining volume of the structure (more than 4.0 million cubic meters) is multifunctional atriums.
For comparison, with an increase in the height of such a pyramid P200 (a geometrically ideal pyramid has a ratio of 3:4:5) by only 50 meters, the parameters of P250 will be: base - 375x375 m; Sbas = 14.1 hectares, Sglass = 235.0 thousand sq.m. There will be an almost twofold increase in the internal volume of the translucent structure, which in this case will be equal to 11.7 million cubic meters, and the amount of space occupied by commercial real estate may increase to 0.8 - 1.0 million square meters. Moreover, what is especially attractive is that the area of the enclosing structures of the P250 pyramid will almost double! less than the total area of the enclosing structures of internal supporting buildings. Specialists should understand the importance of this ratio.
With a further increase in the internal volume of the BSZS and giving it a dome-shaped shape, a decrease in the ratio of the area of the enclosing structures of the translucent complex to the sum of all useful areas interior spaces(as well as to the sum of the areas of the enclosing structures of internal buildings), will change in a very pleasing progression, i.e. the process of such construction will become more and more economically attractive!
Sports centers with translucent coating.
To others promising direction the use of multi-belt cable translucent coverings, today we see the construction of indoor football stadiums and other long-span sports facilities. Every year the demand for indoor sports stadiums in the world is increasing (for example, not only Europeans and North Americans are building large indoor stadiums for themselves, but also less wealthy countries such as Argentina and Kazakhstan have recently built such structures, and the Philippines is now building, as they say , the largest indoor stadium in the world). In anticipation of preparations for the 2018 football championship, the demand for such facilities may also emerge in Russia.
The uniqueness and high cost of currently existing long-span sports structures (with a span of 120-150 m or more) lies in the fact that each such structure is carried out to the maximum capabilities of the construction industry of the place of its construction, is associated with numerous complex and accurate calculations of load-bearing structures, increased responsibility and significant material intensity of implemented solutions. The disadvantages of the ceilings of all these long-span structures are the same: they are complex, bulky, metal-intensive, and therefore irrational and extremely expensive. In addition, due to the powerful load-bearing metal structures of the coating, the insolation of all indoor stadiums today is extremely low, which makes it very difficult to maintain the natural grass surface of modern sports arenas in proper condition.
Fig. 13. Football stadium in Poland. At EURO 2012.
Fig. 14. Wembley Stadium is the most famous stadium in England
It seems that the use of translucent multi-belt cable coverings should radically change this unfavorable state of affairs in the construction of long-span buildings. sports facilities(the sketches in Fig. 15-19 show one of the possible options for the construction of a relatively inexpensive indoor multifunctional sports complex).
Rice. 15-18 sketches of a large indoor stadium.
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1 and 2 – buildings that serve as supporting structures for the translucent coating;
4 – multi-belt cable systems;
10 – guy ropes;
11 – 3-belt cable translucent covering;
18 and 19 – spectator stands;
21 – self-supporting translucent structures
Rice. 19. Section of a 3-belt cable translucent covering (see designation 4 and 11, in Fig. 17)
5 - high-strength metal cable;
6 - cable covering belt;
7 - spacer stand;
8 - horizontal spacer-stretch:
12 - translucent coating elements;
13 - frame structure of the translucent coating.
Multi-belt cable systems (4) (overlapping the span between supports (1 and 2) are inclined outward of the structure due to the difference in the heights of the supporting buildings and are the basis for placing on top of them a sliding translucent covering (11), made of frame structures (13) and translucent elements ( 12) .
The multi-belt cable system, guy ropes (10) and other special technical solutions will provide the cable covering with the necessary rigidity and resistance to the perception of all design loads.
Between the supporting buildings (1 and 2), along the contour of the outer walls of the stadium, self-supporting translucent structures (21) are provided, which make the contour of the outer walls closed.
The use of multi-belt cable coverings will be able to provide all new stadiums with the simplest, most reliable and relatively inexpensive design of translucent covering, while at the same time providing better insolation of the arena than in all indoor stadiums built to date.
The construction of long-span multi-belt cable-based translucent coverings today is not a very difficult task, since in construction practice there is many years of experience in the use of long-span cable-stayed coverings, which basically use the same technical solutions, materials, products and equipment, and the same technical specialists.
A large and beautiful, indoor and comfortable modern sports center is necessary for every developing city, not only for holding events in decent conditions sports competitions throughout the year, but also for the widespread involvement of the urban population in active sports and their personal health. To achieve this, a multifunctional sports complex may include not only a high-quality football field, numerous gyms, swimming pools and fitness centers, but any choice of facilities for recreational and educational activities various types sports, and the high-rise part of the sports complex, if desired, can accommodate hotel and office centers close to the profile of the facility.
With the help of the best specialized construction companies(for example, French " Freyssinet International & Cie" or Japanese "TOKYO ROPE MFG.CO, LTD.", which are world leaders in the design and manufacture of cable-stayed structures), it is possible to begin building the proposed long-span translucent objects today.
Fig. 20. Dome-shaped protective structure with a translucent coating.
Prospects for the architecture of long-span translucent complexes.
The huge atrium spaces of the BSZS can combine many tasks. For example, atriums with volumes of millions of cubic meters will be able to accommodate the largest luxurious water park, a full-fledged sports stadium, and much more at the same time. But, it seems that in the future, the majority of BSZS will prefer the opportunity to place large and cozy landscape gardens with sports and children's playgrounds, fountains and waterfalls, enclosures with exotic animals and picturesque ponds, outdoor swimming pools and cafes on the lawns. After all, everyone is so evergreen blooming garden will give residents and guests of the BSZS the opportunity to communicate daily with wildlife - both in the hottest summer months, and the long rainy days of autumn, and in the snowy cold months of winter.
Fighters for the conservation of nature should like the fact that during the construction of the BSZS, the process of penetration of living nature inside the huge man-made translucent structures is intensified. By occupying spaces specially prepared for it in the BSZS and forming sustainable ecosystems in them (with the active help of humans), nature will be able to qualitatively fill the architectural objects of the future, making them more functional and more attractive to people. At the same time, in the atrium spaces organized by people, the best BSZS, mutualism (mutually beneficial cohabitation) of nature and man will undoubtedly occur.
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Fig.21-22. Atriums of American hotels owned by the famous Gaylord Hotels.
The positive results that will be obtained during the construction of the BSZS fully meet the needs of modern urban planning. This is the economic and environmental attractiveness of the structures; intensive development of the artificial human environment, closely related to the natural environment and ensuring a high quality of life for people; the formation of a new type of eco-cities and improvement of the environmental situation in existing megacities; the emergence of new popular areas for the development of technical progress and significant savings in natural resources.
BSZS according to many criteria the best way comply with the principles of Green Buildings, and will contribute not only to improving the quality of construction projects, but also to preserving the environment.
Construction of the BSZS will helpdecide the following important tasks of “sustainable development” and the requirements of the “green” standards LEED, BREEAM, DGWB:
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reducing the level of consumption of energy and material resources by buildings;
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reducing adverse impacts on natural ecosystems;
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ensuring a guaranteed level of comfort in the human environment;
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creation of new energy-efficient and energy-saving products, new jobs in the production and maintenance sectors;
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formation of public demand for new knowledge and technologies in the field of renewable energy.
Atriums of translucent structures will certainly return our courtyards to their former relevance and relevance, as a newly created public space that is charming in many respects, freed from cars and filled with sunlight, coziness, and comfort.
The design features of the BSZS and their reasonable use will, in the future, make it possible to optimize the construction of such structures in such a way that constructing a complex of buildings covered with a translucent dome will be much cheaper than constructing the same complex of buildings under identical conditions, but without a protective dome.
So, it is obvious that the cost of translucent coating and operating costs (with correct and purposeful movement in this direction) will decrease with increasing volume of the structure (not in absolute terms, but relative to costs per 1 square meter of usable area). This natural conclusion is confirmed by ordinary logic, common sense, and mathematics.
And a several-fold reduction in the area of the enclosing structures of the BSZS, relative to the sum of the areas of the enclosing structures of internal buildings, will inevitably lead to a decrease in the energy consumption for heating the BSZS complex and for its air conditioning, relative to the same volume of ordinary buildings not protected by a translucent shell.
At the same time, all internal buildings of the BSZS will have a simplified finishing of external walls (without expensive coatings and lack of insulation), and window openings will not necessarily be glazed with double-glazed windows, which will inevitably affect the cost of the foundations. The main heating and air conditioning systems of interior buildings can be moved into atrium spaces, making interior living and office spaces simpler, more efficient, etc.
New eco-cities in the future, it seems, may well consist mainly of BSZS located close to each other and as autonomous as possible. Such translucent structures will be built among wildlife and integrated into the natural landscape, and will also be connected to each other and to other cities by the most modern high-speed transport communications. This will probably lead not only to a complete abandonment of personal vehicles by many residents of the eco-cities of the future, due to their uselessness, but will also be able to permanently eliminate places where the flow of people and the flow of cars dangerously intersect.
But the most important result of the construction of eco-sustainable, long-span translucent structures is the expansion and improvement of a comfortable human environment, without negative consequences for nature.
Saint Petersburg
06/09/2013
Notes
:
. Dome over Houston" - http://youtu.be/vJxJWSmRHyE
;
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The largest tent in the world
- http://yo www.youtube.com/watch utu.be/W3PfL2WY5LM
;
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"Tropical Islands" - www.youtube.com/watch ;
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Masdar City - www.youtube.com/watch;
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Long span suspension bridge -
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Bibliography
:
1. Marcus Vitruvius Pollio, de Architectura - the work of Vitruvius in English translation Gwilta (1826);
2. L G. Dmitriev, A. V. Kasilov. "Cable-stayed coverings". Kyiv. 1974;
3. Zverev A.N. Long-span roofing structures for public and industrial buildings. St. Petersburg State University of Civil Engineering - 1998;
4. Kirsanov N.M. Hanging and cable-stayed structures. Stroyizdat - 1981;
5. Smirnov V.A. Suspension bridges of large spans. Higher school. 1970;
6. Eurasian patent No. 016435 - Protective structure with a long-span translucent coating - 2012;
7. 
Fig.23-28. Atriums of the American chain of upscale hotels "Gaylord Hotels".
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 for installing coating elements;
c) the presence, in some cases, of large parts and structures of the building, whatnots, stands of indoor stadiums, foundations for equipment, bulky equipment, etc. under the covering.
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 of internal parts of 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
In recent years, a large number of thin-walled spatial reinforced concrete structures coverings in the form of shells, folds, tents, etc. 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 both public and industrial buildings.
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In Fig. Figure 20 shows geometric diagrams of precast reinforced concrete shells, rectangular in plan.
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 using various methods, differing mainly in the presence or absence of mounting 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 constructive solution Installation of domes is carried out using a temporary support, in a hinged way 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 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 supporting 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.
The Olympic sports complex is designed as a spatial structure of an elliptical shape 183×224 m. Along the outer contour of the ellipse, with a pitch 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 high-strength bolts were installed (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.
Long-span buildings include theaters, concert and gyms, exhibition pavilions, garages, hangars, aircraft and shipyards and other buildings with spans of main load-bearing structures of 50 m or more. As a rule, such buildings are designed as single-span. They are covered with beam systems (mainly trusses), frames, arches, cable-stayed (hanging), combined and other structures.
Significant forces arise in the truss rods of large spans; therefore, instead of the traditional sections of two angles, double-walled composite sections are used. The height of the trusses is assigned within the l/s-Vis span, and it turns out to be more than 3.8 m. Trusses of this height cannot be transported by rail; they are assembled at the construction site.-
The frames are used in building coverings with spans of 60-120 m. Due to the rigid connection of the crossbar with the racks, the bending moments in the span will be less than in a beam structure: This allows not only to reduce the cross-sectional area of the chords, but also the height of the crossbar, and therefore the height of the building . Both hingeless and double-hinged frames are used. Hinged ones are lighter than double-hinged ones, but they require larger foundations and are more sensitive to temperature changes and support settlements. It is not recommended to use them in subsidence soils. Double-wall sections of truss chords
Arches are used in coverings of long-span buildings with spans up to: 200 m. They are more profitable than beam and frame systems. Arches are: solid and through; non-hinged, double-hinged and three-hinged. Hinged arches with the same load are lighter than double-hinged ones, but for them, like for hingeless frames, massive foundations are required and they are so. they are more sensitive to changes in temperature and settlement of supports.
Most often, through double-hinged arches with a lifting boom equal to Vs-Ve are used. span. As the lifting boom increases, the longitudinal force in the arch decreases and the bending moment increases;
The cross-sections of the arch rods can be single-walled or double-walled
The stability of the main load-bearing structures (trusses, frames, arches) is ensured by horizontal and vertical connections. First of all, connections must be installed that secure the compressed belts of through structures
Frames and arches are statically indeterminate systems. Hinged frames and arches are three times statically indeterminate, double-hinged frames are once statically indeterminate. Usually, a thrust is taken as an extra unknown - a force, the approximate value of which for through frames and arches can be found using the formulas given in the designer's handbook.
Knowing the thrust, they determine the bending moments M, longitudinal N and transverse forces Q in the frame or arch as in a statically determinate structure, and from them the forces in the rods.
The forces in the rods of through frames and arches can also be determined by constructing force diagrams. Based on the forces obtained, the sections of the rods are selected, the nodes and connections are calculated in the same way as is done for trusses.
The dead weight of the load-bearing structures and the weight of the roof in< большепролетных сооружениях является основной нагрузкой, существенно влияющей на расход металла на покрытие, поэтому при выборе их конструктивной фор-» мы следует отдавать предпочтение более lightweight designs. Particular efforts should be made to reduce the dead weight of the roof by using aluminum and other roofing panels with light, effective insulation.
Hanging and cable-stayed coatings are those in which flexible threads, mainly cables, are used as a supporting structure.
The main supporting structures of the hanging system - the cables - work only in tension, so they fully utilize the load-bearing capacity of the material
and it becomes possible to use steel of the highest strength.
Their transportation and installation are significantly simplified, which reduces the cost of construction. The above is a very important advantage of hanging systems compared to trusses, frames and arches. However, hanging structures also have serious disadvantages: they have increased deformability and require special supports to absorb thrust.
To reduce the deformability of cable stays, various methods of stabilizing them are used. For example, in double-belt cable-stayed systems, the rigidity of the cables is increased due to the construction of so-called stabilizing cables, connected to the load-bearing cables with hangers and spacers or a lattice of flexible prestressed elements.
The thrust depends on the ratio ///. At ///>Y, the increase in thread sag with increasing load is insignificant and can be neglected. In this case, the thrust can be determined by the formula. The cross-section of the cable is selected based on the force T.
For cable stays, steel ropes, bundles and strands of high-strength wire, round hot-rolled steel are used increased strength And thin sheets.
In combined systems, concentrated forces are transferred to a flexible thread through a rigid element, which makes it possible to significantly reduce their deformability.
For long-span buildings, in particular for hangars, a cantilever combined system is used, consisting of a rigid element and suspensions. The truss serves as a rigid element, which redistributes the concentrated forces between the suspensions. The latter serve as intermediate supports for the truss, and it operates as a continuous beam on elastically subsiding supports. .
The advantage of a console combined system is that for a rigid element (truss) there is no need to provide a rigid support at the second end. Thanks to this, large-sized gate structures can be easily created for hangars.
Long-span buildings can also be covered with spatial systems in the form of vaults, folds and domes.
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