Fiberglass profiles are visually known, standard profiles designed for various applications in construction and design, made of fiberglass.
Possessing the same external parameters as profiles made from traditional materials, profiled fiberglass has a number of unique characteristics.
Fiberglass profiles have one of the highest strength-to-weight ratios of any structural product, as well as excellent corrosion resistance. The products have high resistance to ultraviolet radiation, a wide range of operating temperatures (-100°C to +180°C), as well as fire resistance, which allows the use of this material in various areas of construction, especially when used in areas dangerous voltage, and in the chemical industry.
PRODUCTION OF GLASS PLASTIC PIPES AND PROFILES
The profiles are manufactured using the pultrusion method, a feature of the technology that This consists of continuous drawing of roving made of filament threads, pre-impregnated with a multicomponent system based on binders of various resins, hardeners, thinners, fillers, and dyes.
The fiberglass is impregnated with resin and then passed through a heated die. the desired shape, in which the resin hardens. The result is a profile of a given shape. Fiberglass profiles are reinforced on the surface with a special non-woven fabric (mat), thanks to which the products acquire additional rigidity. The profile frame is covered with fleece impregnated with epoxy resin, which makes the product resistant to ultraviolet radiation.
A feature of pultrusion technology is the production of straight products with a constant cross-section along the entire length.
The cross-section of the fiberglass profile can be any, and its length is determined in accordance with the wishes of the customer.
FRP structural profile comes in a wide range of shapes including I-beam, equal-flange, equal-flange, square pipe, round pipe, as well as a corner for laying when concreting the most different sizes, which can be used instead of the traditional metal corner subject to rapid destruction from rust.
Most often, a fiberglass profile is made of orthophthalic resin.
Depending on the operating conditions, it is possible to produce profiles from other types of resins:
- - vinylester resin: intended for use in conditions where high corrosion resistance is required from the material;
- epoxy resin : has special electrical properties, making products made from it optimal for use in hazardous voltage areas;
- acrylic resin: products made from it have low smoke emission in case of fire.
GLASS PLASTIC PROFILES STALPROM
In our company you can purchase standard and non-standard fiberglass profiles of any size according to your wishes and requirements. The main list of fiberglass profiles is as follows:
Corner
Dimensions of this material may be different. They are used in almost all fiberglass structures. Structurally, they are used in fiberglass staircases, lighting installations, in the bases of bridges, and transitions made of fiberglass flooring.
Corner symbol:
a – width,
b – height,
c – thickness.C-profile (C-profile)
Due to their corrosion resistance, fiberglass C-profiles are used primarily in the chemical industry.
Symbol for C-shaped profile:
a – width,
b – height,
c – opening width,
d – thickness.Fiberglass beam
Can be used either as a part of an integrated solution, or as an independent structure (fiberglass railings).
Beam symbol:
a – width,
b – height.I-beams
Fiberglass I-beams are most often used as load-bearing structures that cover large spans and are able to carry various loads. I-beams are the optimal design solution in the form of a base for fiberglass flooring, staircases, lighting installations, bridges, etc.
I-beam symbol:
a – width,
b – height,
c – thickness.Profile "Hat"
Used as an insulating profile mainly in the electronics industry.
Profile symbol:
a – width,
b – size of the upper part of the profile,
c – thickness.Rectangular pipes
The products are capable of bearing both vertical and horizontal loads.
Pipe designation:
a – width,
b – height,
c – wall thickness.Fiberglass rod is used as fiberglass antenna, sun umbrellas, profiles in model making, etc.
Bar symbols:
a – diameter.Taurus
They are used as additional structures in fiberglass walkways, stages, load-bearing surfaces, etc.
Brand symbols:
a – height,
b – width,
c – thickness.Round pipe
Such fiberglass pipes are not used in structures with internal pressure.
Pipe symbols:
a – outer diameter,
b – internal diameter.Intended for use as the basis of a structure, such as a staircase, staircase or work platform, gangway.
Channel symbols:
a – width,
b – height,
c/d – wall thickness.Z-profile (Z-profile)
Designed for use in gas cleaning facilities.
Profile legend:
a – width of the upper part of the profile,
b – height,
c – width of the lower part of the profile.
The dimensions of this material may vary. They are used in almost all fiberglass structures.
Construction is an area in which the chemical industry works tirelessly, creating new alloys and materials for the production of various products. One of the most important and promising achievements in this area in recent years is the results associated with work on such a composite material as fiberglass. Many engineers and builders call it the material of the future, since it has managed to surpass in its qualities many metals and alloys, including alloy steel.
What is fiberglass? This is a composite that has two components: a reinforcing and a binding base. The first one is fiberglass, the second one is different in its own way. chemical composition resin. Variations in the amount of both allow you to make fiberglass resistant to the conditions of almost any environment. But it should be understood that there is no universal type fiberglass, each of them is recommended for use in certain operating conditions.
Fiberglass is interesting to designers because finished products made from it appear simultaneously with the material itself. This feature gives a lot of scope for imagination, allowing you to produce a product with individual physical and mechanical characteristics according to the client’s specified parameters.
One of the most common fiberglass building materials is grating. Unlike steel decking, it is produced by casting, which gives it such characteristics as low thermal conductivity, isotropy, and of course, like steel materials, strength and durability.
Stair steps are made from fiberglass grating, however, the entire structure is also made from fiberglass parts: racks, handrails, supports, channels.
Of course, such stairs are very durable, they are not afraid of corrosion and exposure to chemical substances. They are easy to transport and install. Unlike metal structures, several people are enough to install them. An additional advantage is the ability to choose colors, which increases the visual appeal of the object.
Gangways made of fiberglass have become very popular. Their reliability is due to the same unique characteristics of the composite we are describing. Pedestrian areas equipped with fiberglass gangways do not require special maintenance; their operational capabilities are much higher than those of the same type of metal structures. It has been proven that the service life of fiberglass is much longer than the latter and amounts to more than 20 years.
Another highly effective offering is the fiberglass handrail system. All railing parts are very compact and easy to assemble by hand. In addition, the client has many variations of the finished design, as well as the opportunity to implement his own project.
Due to the dielectric properties of fiberglass, cable channels are made from it. The isotropy of this material increases the demand for products planned for use in facilities sensitive to electromagnetic vibrations.
In general, it can be noted that the range of fiberglass products is quite wide. Working with it, builders and designers can realize the most fantastic ideas. All designs offered by our company are reliable and durable. The quality of fiberglass determines its relatively high price, but at the same time it is the optimal ratio of the advantages of this material and the demand for it. And at the same time, it is important to understand that the costs of its purchase will pay off in the future due to the reduction in costs of its transportation, installation and subsequent maintenance.
Fiberglass reinforcement takes an increasingly strong position in modern construction. This is due, on the one hand, to its high specific strength (the ratio of strength to specific weight), on the other hand, to high corrosion resistance, frost resistance, and low thermal conductivity. Structures using fiberglass reinforcement are non-electrically conductive, which is very important to eliminate stray currents and electroosmosis. Due to the higher cost compared to steel reinforcement, fiberglass reinforcement is used mainly in critical structures that require special requirements. Such structures include offshore structures, especially those parts that are located in an area of variable water level.
CORROSION OF CONCRETE IN SEA WATER
The chemical effect of sea water is mainly due to the presence of magnesium sulfate, which causes two types of concrete corrosion - magnesium and sulfate. In the latter case, a complex salt (calcium hydrosulfoaluminate) is formed in the concrete, increasing in volume and causing cracking of the concrete.
Another strong corrosion factor is carbon dioxide, which is released by organic matter during decomposition. In the presence of carbon dioxide, insoluble compounds that determine strength are converted into highly soluble calcium bicarbonate, which is washed out of the concrete.
Sea water acts most strongly on concrete located directly above the top water level. When water evaporates, a solid residue remains in the pores of concrete, formed from dissolved salts. The constant flow of water into concrete and its subsequent evaporation from open surfaces leads to the accumulation and growth of salt crystals in the pores of concrete. This process is accompanied by expansion and cracking of concrete. In addition to salts, surface concrete experiences alternating freezing and thawing, as well as wetting and drying.
In the zone of variable water levels, concrete is destroyed to a slightly lesser extent due to the absence of salt corrosion. The underwater part of concrete, which is not subject to the cyclic action of these factors, is rarely destroyed.
The work provides an example of the destruction of a reinforced concrete pile pier, the piles of which, 2.5 m high, were not protected in the zone of variable water horizon. A year later, it was discovered that concrete had almost completely disappeared from this area, so that the pier was supported by only reinforcement. Below the water level the concrete remained in good condition.
The possibility of producing durable piles for offshore structures lies in the use of surface fiberglass reinforcement. Such structures are not inferior in corrosion resistance and frost resistance to structures made entirely of polymer materials, and surpass them in strength, rigidity and stability.
The durability of structures with external fiberglass reinforcement is determined by the corrosion resistance of fiberglass. Due to the tightness of the fiberglass shell, concrete is not exposed to the environment and therefore its composition can be selected only on the basis of the required strength.
FIBER FIBER REINFORCEMENT AND ITS TYPES
For concrete elements where fiberglass reinforcement is used, the design principles of reinforced concrete structures are generally applicable. The classification according to the types of fiberglass reinforcement used is similar. Reinforcement can be internal, external or combined, which is a combination of the first two.
Internal non-metallic reinforcement is used in structures operated in environments that are aggressive to steel reinforcement, but not aggressive to concrete. Internal reinforcement can be divided into discrete, dispersed and mixed. Discrete reinforcement includes individual rods, flat and spatial frames, and meshes. A combination is possible, for example, of individual rods and meshes, etc.
Most simple view Fiberglass reinforcement are rods of the required length, which are used instead of steel ones. Not inferior to steel in strength, fiberglass rods are significantly superior in corrosion resistance and are therefore used in structures in which there is a risk of reinforcement corrosion. Fiberglass rods can be fastened into frames using self-locking plastic elements or by binding.
Dispersed reinforcement consists of introducing concrete mixture when mixing chopped fibers (fibers), which are distributed randomly in concrete. Using special measures, directional arrangement of fibers can be achieved. Concrete with dispersed reinforcement is usually called fiber-reinforced concrete.
In case of aggressiveness of the environment to concrete effective protection is external reinforcement. In this case, external sheet reinforcement can simultaneously perform three functions: strength, protective and formwork functions during concreting.
If external reinforcement is not enough to withstand mechanical loads, additional internal reinforcement is used, which can be either fiberglass or metal.
External reinforcement is divided into continuous and discrete. Continuous is a sheet structure that completely covers the surface of the concrete, discrete is mesh-type elements or individual strips. Most often, one-sided reinforcement of the tensile face of a beam or slab surface is carried out. With one-sided surface reinforcement of beams, it is advisable to place bends of the reinforcement sheet on the side faces, which increases the crack resistance of the structure. External reinforcement can be installed both along the entire length or surface of the load-bearing element, and in individual, most stressed areas. The latter is done only in cases where protection of concrete from exposure to an aggressive environment is not required.
EXTERNAL GLASS PLASTIC REINFORCEMENT
The main idea of structures with external reinforcement is that a sealed fiberglass shell reliably protects the concrete element from environmental influences and, at the same time, performs the functions of reinforcement, taking mechanical loads.
There are two possible ways to obtain concrete structures in fiberglass shells. The first involves the manufacture of concrete elements, drying them, and then enclosing them in a fiberglass shell by multi-layer winding with glass material (fiberglass, glass tape) with layer-by-layer resin impregnation. After polymerization of the binder, the winding turns into a continuous fiberglass shell, and the entire element into a pipe-concrete structure.
The second is based on the preliminary production of a fiberglass shell and its subsequent filling with concrete mixture.
The first way to obtain structures that use fiberglass reinforcement makes it possible to create preliminary transverse compression of concrete, which significantly increases the strength and reduces the deformability of the resulting element. This circumstance is especially important, since the deformability of pipe-concrete structures does not allow taking full advantage of the significant increase in strength. Preliminary transverse compression of concrete is created not only by the tension of the glass fibers (although quantitatively it constitutes the main part of the force), but also due to the shrinkage of the binder during the polymerization process.
GLASS PLASTIC REINFORCEMENT: CORROSION RESISTANCE
The resistance of fiberglass plastics to aggressive environments mainly depends on the type of polymer binder and fiber. When internally reinforcing concrete elements, the durability of fiberglass reinforcement should be assessed not only in relation to external environment, but also in relation to the liquid phase in concrete, since hardening concrete is an alkaline environment in which the commonly used aluminoborosilicate fiber is destroyed. In this case, the fibers must be protected with a layer of resin or fibers of a different composition must be used. In the case of non-wetted concrete structures, no corrosion of fiberglass is observed. In wetted structures, the alkalinity of the concrete environment can be significantly reduced by using cements with active mineral additives.
Tests have shown that fiberglass reinforcement is more than 10 times more durable in an acidic environment, and more than 5 times more durable in salt solutions steel reinforcement. The most aggressive environment for fiberglass reinforcement is an alkaline environment. A decrease in the strength of fiberglass reinforcement in an alkaline environment occurs as a result of the penetration of the liquid phase into the glass fiber through open defects in the binder, as well as through diffusion through the binder. It should be noted that the nomenclature of starting substances and modern technologies The production of polymer materials makes it possible to widely regulate the properties of the binder for fiberglass reinforcement and obtain compositions with extremely low permeability, and therefore minimize fiber corrosion.
GLASS PLASTIC REINFORCEMENT: APPLICATION IN REPAIR OF REINFORCED CONCRETE STRUCTURES
Traditional methods of strengthening and restoring reinforced concrete structures are quite labor-intensive and often require a long shutdown of production. In the case of an aggressive environment, after repairs it is necessary to protect the structure from corrosion. High manufacturability, short hardening time of the polymer binder, high strength and corrosion resistance of external fiberglass reinforcement have determined the feasibility of its use for strengthening and restoring load-bearing elements of structures. The methods used for these purposes depend on the design features of the elements being repaired.
FIBER FIBER REINFORCEMENT: ECONOMIC EFFICIENCY
The service life of reinforced concrete structures when exposed to aggressive environments is sharply reduced. Replacing them with fiberglass concrete eliminates the cost of major repairs, losses from which increase significantly when production is required to be stopped during repairs. The capital investment for the construction of structures using fiberglass reinforcement is significantly higher than for reinforced concrete. However, after 5 years they pay for themselves, and after 20 years the economic effect reaches twice the cost of constructing the structures.
LITERATURE
- Corrosion of concrete and reinforced concrete, methods of their protection / V. M. Moskvin, F. M. Ivanov, S. N. Alekseev, E. A. Guzeev. - M.: Stroyizdat, 1980. - 536 p.
- Frolov N.P. Fiberglass reinforcement and fiberglass concrete structures. - M.: Stroyizdat, 1980.- 104 p.
- Tikhonov M.K. Corrosion and protection of marine structures made of concrete and reinforced concrete. M.: Publishing House of the USSR Academy of Sciences, 1962. - 120 p.
In foreign construction, the main application of all types of fiberglass is translucent fiberglass, which is successfully used in industrial buildings in the form of sheet elements with a corrugated profile (usually in combination with corrugated sheets of asbestos cement or metal), flat panels, domes, and spatial structures.
Translucent enclosing structures serve as a replacement for labor-intensive and low-cost window units and skylights in industrial, public and agricultural buildings.
Translucent fencing has found wide application in walls and roofs, as well as in elements of auxiliary structures: canopies, kiosks, fencing of parks and bridges, balconies, flights of stairs and etc.
In cold enclosures industrial buildings Corrugated sheets of fiberglass are combined with corrugated sheets of asbestos cement, aluminum and steel. This makes it possible to use fiberglass in the most rational way, using it in the form of separate inclusions in the roof and walls in quantities dictated by lighting considerations (20-30% of the total area), as well as fire resistance considerations. Fiberglass sheets are attached to the purlins and half-timbers with the same fasteners as sheets of other materials.
Recently, due to a decrease in prices for fiberglass and the production of self-extinguishing material, translucent fiberglass began to be used in the form of large or continuous areas in enclosing structures of industrial and public buildings.
Standard sizes of corrugated sheets cover all (or almost all) possible combinations with profile sheets made of other materials: asbestos cement, clad steel, corrugated steel, aluminum, etc. For example, the English company Alan Blun produces up to 50 standard sizes of fiberglass, including profiles, adopted in the USA and Europe. The assortment of profile sheets made of vinyl plastic (Merly company) and plexiglass (ICI company) is approximately the same.
Along with translucent sheets, consumers are also offered complete parts for their fastening.
Along with translucent fiberglass plastics, in recent years in a number of countries rigid translucent vinyl plastic, mainly in the form of corrugated sheets, has also become increasingly widespread. Although this material is more sensitive to temperature fluctuations than fiberglass, has a lower elastic modulus and, according to some data, is less durable, it nevertheless has certain prospects due to a wide raw material base and certain technological advantages.
Domes made of fiberglass and plexiglass are widely used abroad due to high lighting characteristics, low weight, relative ease of manufacture (especially plexiglass domes), etc. They are produced in spherical or pyramidal shapes with a round, square or rectangular outline in plan. In the USA and Western Europe Mostly single-layer domes are used, but in countries with colder climates (Sweden, Finland, etc.) - two-layer with an air gap and special device for draining condensate, made in the form of a small gutter around the perimeter of the supporting part of the dome.
The area of application of translucent domes is industrial and public buildings. Dozens of companies in France, England, the USA, Sweden, Finland and other countries are engaged in their mass production. Fiberglass domes typically come in sizes from 600 to 5500 mm, And from plexiglass from 400 to 2800 mm. There are examples of the use of domes (composite) of much larger sizes (up to 10 m and more).
There are also examples of the use of reinforced vinyl plastic domes (see Chapter 2).
Translucent fiberglass, which until recently was used only in the form of corrugated sheets, is now beginning to be widely used for the manufacture of large-sized structures, especially wall and roofing panels standard sizes that can compete with similar structures made from traditional materials. There is only one American company, Colwall, which produces three-layer translucent panels up to b m, has used them in several thousand buildings.
Of particular interest are the developed fundamentally new translucent panels of a capillary structure, which have increased thermal insulation ability and high translucency. These panels consist of a thermoplastic core with capillary channels (capillary plastic), covered on both sides with flat sheets of fiberglass or plexiglass. The core is essentially a translucent honeycomb with small cells (0.1-0.2 mm). It contains 90% solids and 10% air and is made mainly from polystyrene, less often plexiglass. It is also possible to use polocarbonate, a thermoplastic with increased fire resistance. The main advantage of this transparent design is its high thermal resistance, which provides significant savings on heating and prevents the formation of condensation even at high humidity air. An increased resistance to concentrated loads, including impact loads, should also be noted.
The standard dimensions of capillary structure panels are 3X1 m, but they can be manufactured up to 10 m long m and width up to 2 m. In Fig. 1.14 shown general form and details of an industrial building, where panels of a capillary structure measuring 4.2X1 were used as light barriers for the roof and walls m. The panels are laid along the long sides on V-shaped spacers and joined at the top using metal overlays with mastic.
In the USSR, fiberglass has found very limited use in building structures (for individual experimental structures) due to its insufficient quality and limited range
(see chapter 3). Basically, corrugated sheets with a small wave height (up to 54 mm), which are used mainly in the form of cold fencing for buildings of “small forms” - kiosks, canopies, light canopies.
Meanwhile, as feasibility studies have shown, the greatest effect can be achieved by using fiberglass in industrial construction as translucent fences for walls and roofs. This eliminates expensive and labor-intensive lantern add-ons. The use of translucent fencing in public construction is also effective.
Fences made entirely of translucent structures are recommended for temporary public and auxiliary buildings and structures in which the use of translucent plastic fencing is dictated by increased lighting or aesthetic requirements (for example, exhibition, sports buildings and structures). For other buildings and structures total area light openings filled with translucent structures are determined by lighting calculations.
TsNIIPromzdanii, together with TsNIISK, Kharkov Promstroyniproekt and the All-Russian Research Institute of Fiberglass and Fiberglass, has developed a number of effective structures for industrial construction. The simplest design are translucent sheets laid along the frame in combination with corrugated sheets of non-porous
transparent materials (asbestos cement, steel or aluminum). It is preferable to use shear wave fiberglass in rolls, which eliminates the need to join sheets widthwise. In case of longitudinal waves, it is advisable to use sheets of increased length (for two spans) to reduce the number of joints above the supports.
Covering slopes in the case of a combination of corrugated sheets made of translucent materials with corrugated sheets of asbestos cement, aluminum or steel should be assigned in accordance with the requirements,
Presented for coatings made of non-transparent corrugated sheets. When constructing coverings entirely of translucent wavy sheets, the slopes should be at least 10% in the case of joining sheets along the length of the slope, 5% in the absence of joints.
The overlap length of translucent corrugated sheets in the direction of the slope of the coating (Fig. 1.15) should be 20 cm with slopes from 10 to 25% and 15 cm with slopes greater than 25%. In wall fences, the overlap length should be 10 cm.
When applying such solutions, serious attention must be paid to the arrangement of fastenings of sheets to the frame, which largely determine the durability of structures. The corrugated sheets are fastened to the purlins with bolts (to steel and reinforced concrete purlins) or screws (to wooden purlins) installed along the crests of the waves (Fig. 1.15). Bolts and screws must be galvanized or cadmium plated.
For sheets with wave sizes 200/54, 167/50, 115/28 and 125/35, fastenings are placed on every second wave, for sheets with wave sizes 90/30 and 78/18 - on every third wave. All extreme wave crests of each corrugated sheet must be secured.
The diameter of bolts and screws is taken according to calculation, but not less than 6 mm. The diameter of the hole for bolts and screws should be 1-2 mm Larger than the diameter of the mounting bolt (screw). Metal washers for bolts (screws) must be bent along the curvature of the wave and equipped with elastic sealing pads. The diameter of the washer is taken by calculation. In places where corrugated sheets are attached, wooden or metal pads are installed to prevent the wave from settling on the support.
The joint across the direction of the slope can be made using bolted or adhesive joints. At bolted connections the overlap length of corrugated sheets is taken to be no less than the length of one wave; bolt pitch 30 cm. Bolted joints of corrugated sheets should be sealed with tape gaskets (for example, elastic polyurethane foam impregnated with polyisobutylene) or mastics. For adhesive joints, the length of the overlap is calculated, and the length of one joint is no more than 3 m.
In accordance with the guidelines for capital construction adopted in the USSR, the main attention in research is paid to large-sized panels. One of these structures consists of a metal frame, working for a span of 6 m, and corrugated sheets supported on it, working for a span of 1.2-2.4 m .
The preferred option is filling with double sheets, as it is relatively more economical. Panels of this design size 4.5X2.4 m were installed in an experimental pavilion built in Moscow.
The advantage of the described panel with a metal frame is the ease of manufacture and the use of materials currently produced by industry. However, three-layer panels with skins made of flat sheets, which have increased rigidity, better thermal properties and require minimal metal consumption, are more economical and promising.
The low weight of such structures allows the use of elements of considerable size, however, their span, as well as corrugated sheets, is limited by maximum permissible deflections and some technological difficulties (the need for large-sized press equipment, joining sheets, etc.).
Depending on the manufacturing technology, fiberglass panels can be glued or integrally molded. Glued panels are made by glueing together flat skins with an element of the middle layer: ribs made of fiberglass, metal or antiseptic wood. For their manufacture, standard fiberglass materials produced by a continuous method can be widely used: flat and corrugated sheets, as well as various profile elements. Glued structures allow the height and pitch of the middle layer elements to be relatively widely varied, depending on the need. Their main disadvantage, however, is the larger number of technological operations, which makes their production more difficult, and also less reliable than in solidly molded panels, the connection of the skins with the ribs.
Fully formed panels are obtained directly from the original components - glass fiber and a binder, from which a box-shaped element is formed by winding the fiber onto a rectangular mandrel (Fig. 1.16). Such elements, even before the binder hardens, are pressed into a panel by creating lateral and vertical pressure. The width of these panels is determined by the length of the box elements and, in relation to the industrial building module, is taken to be 3 m.
Rice. 1.16. Translucent, fully molded fiberglass panels
A - manufacturing diagram: 1 - winding fiberglass filler onto mandrels; 2 - lateral compression; 3-vertical pressure; 4-finished panel after removing the mandrels; b-general view of a panel fragment
The use of continuous rather than chopped fiberglass for solidly molded panels makes it possible to obtain a material in panels with increased values of elasticity modulus and strength. The most important advantage One-step process and increased reliability of the connection of thin ribs of the middle layer with the skins are also important features of integrally molded panels.
At present, it is still difficult to give preference to one or another technological scheme for the manufacture of translucent fiberglass structures. This can be done only after their production has been established and data on the operation of various types of translucent structures have been obtained.
The middle layer of glued panels can be arranged in various options. Panels with a wavy middle layer are relatively easy to manufacture and have good lighting properties. However, the height of such panels is limited by the maximum wave dimensions
(50-54mm), in connection with which A)250^250g250 such panels have ogre
Zero rigidity. More acceptable in this regard are panels with a ribbed middle layer.
When selecting sizes cross section translucent ribbed panels, a special place is occupied by the question of the width and height of the ribs and the frequency of their placement. The use of thin, low and sparsely spaced ribs provides greater light transmission of the panel (see below), but at the same time leads to a decrease in its load-bearing capacity and rigidity. When assigning the spacing of the ribs, one should also take into account the load-bearing capacity of the skin under conditions of its operation under local load and a span equal to the distance between the ribs.
The span of three-layer panels, due to their significantly greater rigidity than corrugated sheets, can be increased for roof slabs to 3 m, and for wall panels - up to 6 m.
Three-layer glued panels with a middle layer of wooden ribs are used, for example, for office premises of the Kiev branch of VNIINSM.
Of particular interest is the use of three-layer panels for the installation of skylights in the roof of industrial and public buildings. The development and research of translucent structures for industrial construction were carried out at TsNIIPromzdanii together with TsNIISK. Based on comprehensive research
work row interesting solutions skylights made of fiberglass and plexiglass, as well as experimental objects were carried out.
Anti-aircraft lights made of fiberglass can be designed in the form of domes or panel construction (Fig. 1.17). In turn, the latter can be glued or solidly molded, flat or curved. Due to the reduced load-bearing capacity of fiberglass, the panels are supported along their long sides on adjacent blind panels, which must be reinforced for this purpose. It is also possible to install special support ribs.
Since the cross-section of a panel is, as a rule, determined by calculating its deflections, in some structures the possibility of reducing deflections is used by appropriately fastening the panel to supports. Depending on the design of such fastening and the rigidity of the panel itself, the deflection of the panel can be reduced both due to the development of the support moment and the appearance of “chain” forces that contribute to the development of additional tensile stresses in the panel. In the latter case, it is necessary to provide design measures that would exclude the possibility of the panel's supporting edges approaching each other (for example, by fastening the panel to a special frame or to adjacent rigid structures).
A significant reduction in deflections can also be achieved by giving the panel a spatial shape. A curved vaulted panel handles static loads better than a flat panel, and its contour facilitates better removal of dirt and water from the outer surface. The design of this panel is similar to that adopted for the translucent covering of the swimming pool in the city of Pushkino (see below).
Skylights in the form of domes, usually rectangular in shape, are arranged, as a rule, double, taking into account our relatively harsh climatic conditions. They can be installed separately
4 A. B. Gubenko
Domes or be interlocked on a covering slab. While in the USSR practical use found only domes made of organic glass due to the lack of fiberglass required quality and sizes.
In the covering of the Moscow Palace of Pioneers (Fig. 1.18) above the lecture hall, the lecture hall is installed in increments of about 1.5 m 100 spherical domes with a diameter of 60 cm. These domes illuminate an area of about 300 m2. The design of the domes rises above the roof, which ensures better cleaning and discharge of rainwater.
In the same building above winter garden another design was used, which consists of triangular bags glued together from two flat sheets organic glass, laid on a spherical steel frame. The diameter of the dome formed by the spatial frame is about 3 m. Plexiglass bags were sealed in the frame with porous rubber and sealed with U 30 m mastic. Warm air, which accumulates in the under-dome space, prevents the formation of condensation on inner surface domes.
Observations of the plexiglass domes of the Moscow Palace of Pioneers showed that seamless translucent structures have undeniable advantages over prefabricated ones. This is explained by the fact that the operation of a spherical dome consisting of triangular packages is more difficult than seamless domes of small diameter. The flat surface of double-glazed windows, the frequent arrangement of frame elements and sealing mastic make it difficult for water to drain and dust to blow off, and in winter time contribute to the formation of snow drifts. These factors significantly reduce the light transmission of structures and lead to disruption of the seal between elements.
Lighting tests of these coatings gave good results. It was found that the illumination from natural light of the horizontal area at the floor level of the lecture hall is almost the same as with artificial lighting. The illumination is almost uniform (variation 2-2.5%). Determination of the influence of snow cover showed that with a thickness of 1-2 cm room illumination drops by 20%. At above-zero temperatures, fallen snow melts.
Anti-aircraft domes made of plexiglass have also found use in the construction of a number of industrial buildings: the Poltava Diamond Tools Plant (Fig. 1.19), the Smolensk Processing Plant, the laboratory building of the Noginsk Scientific Center of the USSR Academy of Sciences, etc. The designs of the domes in these objects are similar. Dimensions of domes along the length 1100 mm, width 650-800 mm. The domes are two-layer, the supporting glasses have inclined edges.
Rod and other load-bearing structures made of fiberglass are used relatively rarely, due to its insufficiently high mechanical properties (especially low rigidity). The scope of application of these structures is of a specific nature, mainly associated with special operating conditions, such as, for example, when increased corrosion resistance, radio transparency, high transportability, etc. are required.
A relatively large effect is achieved by using fiberglass structures, exposed to various aggressive substances that quickly destroy ordinary materials. In 1960, only
in the USA, about $7.5 million was spent (the total cost of translucent fiberglass plastics produced in the USA in 1959 was approximately $40 million). Interest in corrosion-resistant fiberglass structures is explained, according to companies, primarily by their good economic performance indicators. Their weight
Rice. 1.19. Plexiglas domes on the roof of the Poltava Diamond Tools Plant
A - general view; b - design of the support unit: 1 - dome; 2 - condensate collection trough; 3 - frost-resistant sponge rubber;
4 - wooden frame;
5 - metal clamp; 6 - apron made of galvanized steel; 7 - waterproofing carpet; 8 - compacted slag wool; 9 - metal support cup; 10 -slab insulation; 11 - asphalt screed; 12 - granular filling
Slag
Much less steel or wooden structures, they are much more durable than the latter, easy to erect, repair and clean, can be made on the basis of self-extinguishing resins, and translucent containers do not require water meter glasses. Thus, a standard container for aggressive media with a height of 6 m and diameter 3 m weighs about 680 kg, while a similar steel container weighs about 4.5 T. Weight of exhaust pipe with diameter 3 m and height 14.3 mu intended for metallurgical production, is 77-Vio of the weight of a steel pipe with the same bearing capacity; although a fiberglass pipe was 1.5 times more expensive to manufacture, it is more economical than steel
noy, since, according to foreign companies, the service life of such structures made of steel is calculated in weeks, from of stainless steel- for months, similar structures made of fiberglass have been in operation for years without damage. So, a pipe with a height of 60 mm and a diameter of 1.5 m has been in operation for seven years. Previously installed pipe made of stainless steel lasted only 8 months, and its manufacture and installation cost only half as much. Thus, the cost of a fiberglass pipe paid for itself within 16 months.
Fiberglass containers are also an example of durability in aggressive environments. Such a container with a diameter and height of 3 l, intended for various acids (including sulfuric), with a temperature of about 80 ° C, is operated without repair for 10 years, having served 6 times longer than the corresponding metal one; the repair costs alone for the latter over a five-year period are equal to the cost of a fiberglass container.
In England, Germany and the USA, containers in the form of warehouses and water tanks of considerable height are also widespread (Fig. 1.20).
Along with the indicated large-sized products, in a number of countries (USA, England), pipes, sections of air ducts and other similar elements intended for operation in aggressive environments are mass-produced from fiberglass.
A relatively great effect is achieved by the use of fiberglass structures exposed to various aggressive substances that quickly destroy ordinary materials. In 1960, about $7.5 million was spent on the production of corrosion-resistant fiberglass structures in the USA alone (the total cost of translucent fiberglass plastics produced in the USA in 1959 was approximately $40 million). Interest in corrosion-resistant fiberglass structures is explained, according to companies, primarily by their good economic performance. Their weight is much less than steel or wooden structures, they are much more durable than the latter, they are easy to erect, repair and clean, they can be made on the basis of self-extinguishing resins, and translucent containers do not require water meter glasses. Thus, a serial tank for aggressive environments with a height of 6 m and a diameter of 3 m weighs about 680 kg, while a similar steel tank weighs about 4.5 tons. The weight of an exhaust pipe with a diameter of 3 m and a height of 14.3 m intended for metallurgical production, forms part of the weight steel pipe with the same load-bearing capacity; Although a fiberglass pipe was 1.5 times more expensive to manufacture, it is more economical than steel, since, according to foreign companies, the service life of such structures made of steel is calculated in weeks, of stainless steel - in months, similar structures made of fiberglass are operated without damage for years. Thus, a pipe with a height of 60 m and a diameter of 1.5 m has been in operation for seven years. The previously installed stainless steel pipe lasted only 8 months, and its production and installation cost only half as much. Thus, the cost of a fiberglass pipe paid for itself within 16 months.
Fiberglass containers are also an example of durability in aggressive environments. Such containers can be found even in traditional Russian baths, since they are not influenced by high temperatures, more information about various quality equipment for baths can be found on the website http://hotbanya.ru/. Such a container with a diameter and height of 3 m, intended for various acids (including sulfuric), with a temperature of about 80 ° C, is operated without repair for 10 years, serving 6 times longer than the corresponding metal one; the repair costs alone for the latter over a five-year period are equal to the cost of a fiberglass container. In England, Germany and the USA, containers in the form of warehouses and water tanks of considerable height are also widespread. Along with the indicated large-sized products, in a number of countries (USA, England), pipes, sections of air ducts and other similar elements intended for operation in aggressive environments are mass-produced from fiberglass.
