Fiberglass materials. Typical areas of application of fiberglass structures in construction. External fiberglass reinforcement
Fiberglass profiles are visually known, standard profiles designed for various applications in construction and design, made of fiberglass.
Having the same external parameters as profiles 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 are highly resistant 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 operating in hazardous voltage zones, 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 of the desired shape, in which the resin hardens. As a result, a profile of a given shape is obtained. 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
The dimensions of this material may vary. 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 span large spans and are capable of carrying various loads. I-beams are the optimal design solution in the form of a base for fiberglass flooring, staircases, lighting installations, walkways, 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.
Among the many new and varied structural synthetic materials The most widely used for the construction of small ships are fiberglass plastics, consisting of fiberglass reinforcing material and a binder (most often based on polyester resins). These composite materials have a number of advantages that make them popular among designers and builders of small vessels.
The process of curing polyester resins and producing fiberglass based on them can occur at room temperature, which makes it possible to manufacture products without heating and high blood pressure, which in turn eliminates the need for complex processes and expensive equipment.
Polyester fiberglass plastics have high mechanical strength and are not inferior, in some cases, to steel, while having a much lower specific gravity. In addition, fiberglass plastics have a high damping capacity, which allows the boat hull to withstand large shock and vibration loads. If the impact force exceeds the critical load, then the damage in the plastic case is, as a rule, local and does not spread over a large area.
Fiberglass has a relatively high resistance to water, oil, diesel fuel, atmospheric influences. Fuel and water tanks are sometimes made from fiberglass, and the translucency of the material allows one to observe the level of the stored liquid.
The hulls of small ships made of fiberglass are usually monolithic, which eliminates the possibility of water penetrating inside; they do not rot, do not corrode, and can be repainted every few years. For sports vessels, the ability to obtain a perfectly smooth surface is important. outer surface body with low friction resistance when moving in water.
However, as a structural material, fiberglass also has some disadvantages: relatively low rigidity, a tendency to creep under constant loads; connections of fiberglass parts have relatively low strength.
Fiberglass plastics based on polyester resins are manufactured at temperatures of 18 - 25 0 C and do not require additional heating. Curing of polyester fiberglass takes place in two stages:
Stage 1 – 2 – 3 days (the material gains approximately 70% of its strength;
Stage 2 – 1 – 2 months (increasing strength to 80 – 90%).
To achieve maximum structural strength, it is necessary that the binder content in fiberglass is minimally sufficient to fill all the gaps of the reinforcing filler with the chain to obtain a monolithic material. In conventional fiberglass, the binder-filler ratio is usually 1:1; in this case, the total strength of glass fibers is used by 50 - 70%.
The main reinforcing fiberglass materials are strands, canvases (glass mats, chopped fiber and glass fabrics.
The use of woven materials using twisted glass fibers as reinforcing fillers for the manufacture of fiberglass hulls of boats and yachts is hardly justified both economically and technologically. On the contrary, nonwoven materials for the same purposes are very promising and the volume of their use is growing every year.
The cheapest type of material is glass strands. In the bundle, glass fibers are arranged in parallel, which makes it possible to obtain fiberglass with high tensile strength and longitudinal compression(along the fiber length). Therefore, strands are used to produce products where it is necessary to achieve predominant strength in one direction, for example, frame beams. When constructing buildings, cut (10 - 15 mm) strands are used to seal structural gaps formed when making various types of connections.
Chopped glass strands are also used for the manufacture of hulls of small boats and yachts, obtained by spraying fibers mixed with polyester resin onto an appropriate mold.
Fiberglass - roll materials with chaotic laying of glass fibers in the plane of the sheet - also made from strands. Fiberglass plastics based on canvas have lower strength characteristics than fabric-based fiberglass plastics, due to the lower strength of the canvases themselves. But fiberglass, cheaper, has a significant thickness and low density, which ensures their good impregnation with the binder.
Layers of fiberglass can be bonded in the transverse direction chemically (using binders) or mechanical stitching. Such reinforcing fillers are laid on surfaces with a large curvature more easily than fabrics (fabric forms folds and requires preliminary cutting and adjustment). Hopsts are used primarily in the manufacture of hulls of boats, motorboats, and yachts. In combination with fiberglass fabrics, canvases can be used for the manufacture of ship hulls, which are subject to higher strength requirements.
The most responsible structures are made on the basis of fiberglass. Most often, satin weave fabrics are used, which provide a higher utilization rate of the strength of the threads in fiberglass.
In addition, fiberglass tow is widely used in small shipbuilding. It is made from untwisted threads - strands. This fabric has greater weight, lower density, but also lower cost than fabrics made from twisted threads. Therefore, the use of rope fabrics is very economical, taking into account, moreover, the lower labor intensity when molding structures. In the manufacture of boats and boats, rope fabric is often used for the outer layers of fiberglass, while the inner layers are made of hard fiberglass. This achieves a reduction in cost of the structure while simultaneously ensuring the necessary strength.
The use of unidirectional rope fabrics, which have predominant strength in one direction, is very specific. When molding ship structures, such fabrics are laid so that the direction of greatest strength corresponds to the greatest effective stresses. This may be necessary in the manufacture of, for example, a spar, when it is necessary to take into account the combination of strength (especially in one direction), lightness, taper, varying wall thickness and flexibility.
Nowadays, the main loads on the spar (in particular, on the mast) act mainly along the axes; it is the use of unidirectional tow fabrics (when the fibers are located along the spar that provides the required strength characteristics. In this case, it is also possible to manufacture the mast by winding the tow onto a core (wooden, metal etc.), which can subsequently be removed or remain inside the mast.
Currently, the so-called three-layer structures with lightweight filler in the middle.
Tpex-layer construction consists of two outer load-bearing layers made of durable sheet material of small thickness, between which is placed a lighter, although less durable aggregate. The purpose of the filler is to ensure the joint work and stability of the load-bearing layers, as well as to maintain the specified distance between them.
The joint operation of the layers is ensured by their connection with the filler and the transfer of forces from one layer to another by the latter; the stability of the layers is ensured, since the filler creates almost continuous support for them; the required distance between layers is maintained due to sufficient rigidity of the filler.
Compared to traditional single-layer ones, the three-layer structure has increased rigidity and strength, which makes it possible to reduce the thickness of shells, panels and the number of stiffeners, which is accompanied by a significant reduction in the weight of the structure.
Three-layer structures can be made from any materials (wood, metal, plastics), but they are most widely used when using polymer composite materials, which can be used both for load-bearing layers and for filler, and their connection to each other is ensured by gluing.
In addition to the possibility of reducing weight, three-layer structures have other positive qualities. In most cases, in addition to their main function of forming a hull structure, they also perform a number of others, for example, they impart thermal and sound insulation properties, provide a reserve of emergency buoyancy, etc.
Three-layer structures, due to the absence or reduction of set elements, make it possible to more rationally use the internal volumes of the premises, lay electrical routes and some pipelines in the core itself, and make it easier to maintain cleanliness in the premises. Due to the absence of stress concentrators and the elimination of the possibility of fatigue cracks, three-layer structures have increased reliability.
However, it is not always possible to ensure a good bond between the load-bearing layers and the filler due to the lack of adhesives with the necessary properties, as well as insufficient careful adherence technological process gluing. Due to the relatively small thickness of the layers, their damage and filtration of water through them, which can spread throughout the entire volume, are more likely.
Despite this, three-layer structures are widely used for the manufacture of hulls of boats, boats and small vessels (10 - 15 m long), as well as the manufacture of separate structures: decks, superstructures, deckhouses, bulkheads, etc. Note that the hulls of boats and boats, in in which the space between the outer and inner skins is filled with foam plastic in order to ensure buoyancy, strictly speaking, cannot always be called three-layer, since they do not represent flat or curved three-layer plates with a small thickness of the filler. It is more correct to call such structures double-sheathed or double-hulled.
It is most advisable to make elements of deckhouses, bulkheads, etc., which usually have flat, simple shapes, in a three-layer design. These structures are located in the upper part of the hull, and reducing their mass has a positive effect on the stability of the vessel.
The currently used three-layer ship structures made of fiberglass can be classified according to the type of filler as follows: with a continuous filler made of polystyrene foam, balsa wood; with fiberglass honeycomb core, aluminum foil; box-shaped panels made of polymer composite materials; combined panels (box-shaped with polystyrene foam). The thickness of the load-bearing layers can be symmetrical or asymmetrical relative to the middle surface of the structure.
By manufacturing method three-layer structures can be glued, with a foaming filler, molded on special installations.
The main components for the manufacture of three-layer structures are: glass fabrics of the T – 11 – GVS – 9 and TZhS-O,56-0 brands, fiberglass meshes of various brands; Marui polyester resins PN-609-11M, epoxy resins grades ED - 20 (or other grades with similar properties), foam plastics grades PVC - 1, PSB - S, PPU-3s; fire-resistant laminated plastic.
Three-layer structures are made monolithic or assembled from individual elements (sections) depending on the size and shape of the products. The second method is more universal, as it is applicable to structures of any size.
The manufacturing technology of three-layer panels consists of three independent processes: production or preparation of load-bearing layers, production or preparation of filler and assembly and gluing of panels.
The load-bearing layers can be prepared in advance or directly during the formation of the panels.
The aggregate can also be applied either in the form of finished boards or foamed by increasing the temperature or by mixing the appropriate components during the production of the panels. Honeycomb core is manufactured at specialized enterprises and supplied in the form of cut slabs of a certain thickness or in the form of honeycomb blocks that require cutting. Tile foam is cut and processed on carpentry band saws or circular saws, thickness planers and other woodworking machines.
The decisive influence on the strength and reliability of three-layer panels is exerted by the quality of gluing of the load-bearing joints with the filler, which, in turn, depends on the quality of preparation of the bonded surfaces, the quality of the resulting adhesive layer and adherence to gluing regimes. The operations of preparing surfaces and applying adhesive layers are discussed in detail in the relevant literature on gluing.
For gluing load-bearing layers with honeycomb core, adhesives of the BF-2 (hot-curing), K-153 and EPK-518-520 (cold-curing) brands are recommended, and with tile foams, adhesives of the K-153 and EPK-518-520 brands are recommended. The latter provide higher bonding strength than BF-l glue and do not require special equipment to create the required temperature (about 150 0 C). However, their cost is 4 - 5 times higher than the cost of BF - 2 glue, and the curing time is 24 - 48 hours (curing time of BF - 2 - 1 hour).
When foaming foam plastics between the load-bearing layers, applying adhesive layers on them, as a rule, is not required. After gluing and the necessary exposure (7 - 10 days), mechanical processing of the panels can be carried out: trimming, drilling, cutting holes, etc.
When assembling structures from three-layer panels, it should be taken into account that in the joints the panels are usually loaded with concentrated loads and the joints must be reinforced with special inserts made of a material that is denser than the filler. The main types of connections are mechanical, molded and combined.
When fastening saturation parts on three-piece structures, it is necessary to provide internal reinforcements in the fastener, especially when using mechanical fasteners. One of the methods of such strengthening, as well as the technological sequence of the unit, is shown in the figure.
When choosing structural materials for building and infrastructure construction, engineers often choose various types of fiberglass reinforced plastic (FRP), offering optimal combination strength properties and durability.Widespread industrial use of fiberglass began in the thirties of the last century, but until now its use is often limited by a lack of knowledge about what types of this material are applicable in certain conditions. There are many types of fiberglass; their properties, and therefore their areas of application, may differ in many ways. In general, the advantages of using this type of material are as follows:
Low specific gravity (80% less than steel)
Corrosion resistance
Low electrical and thermal conductivity
Permeability to magnetic fields
High strength
Easy to care forIn this regard, fiberglass is a good alternative to traditional construction materials– steel, aluminum, wood, concrete, etc. Its use is especially effective in conditions of strong corrosive effects, since products made from it last much longer and require virtually no maintenance.
In addition, the use of fiberglass is justified from an economic point of view, and not only because products made from it last much longer, but also because of its low specific gravity. Due to the low specific weight, savings on transportation costs are achieved, and installation is also simplified and cheaper. An example is the use of fiberglass walkways at a water treatment plant, the installation of which was completed 50% faster than previously used steel structures.[I]Fiberglass walkways installed on the pier
Despite the fact that it is impossible to list all the areas of application of fiberglass in the construction industry, most of them can be summarized into three groups (types): structural elements of structures, gratings and Wall panels.
[U]Structural elements
There are hundreds of different types structural elements structures made of fiberglass: platforms, walkways, stairs, handrails, protective covers etc.
[I]Fiberglass staircase[U]Grids
Both casting and pultrusion can be used to make fiberglass gratings. The gratings made in this way are used as decking, platforms, etc.
[I]Fiberglass grille[U]Wall panels
Made from fiberglass, wall panels are primarily used in less critical applications such as commercial kitchens and bathrooms, but they are also used in specialty applications such as bulletproof screens.Most often, fiberglass products are used in the following areas:
Construction and architecture
Tool production
Food industry and beverage industry
Oil and gas industry
Water treatment and purification
Electronics and electrical engineering
Construction of swimming pools and water parks
Water transport
Chemical industry
Restaurant and hotel business
Power plants
Pulp - paper industry
MedicineWhen choosing a specific type of fiberglass for use in a particular area, it is necessary to answer the following questions:
Will there be aggressive chemical compounds present in the work environment?
What should the load-bearing capacity be?
In addition, factors such as fire safety, since not all types of fiberglass contain fire retardants.Based on this information, the fiberglass manufacturer, based on the characteristics tables, selects the optimal material. In this case, it is necessary to make sure that the characteristics tables refer to the materials of this particular manufacturer, since the characteristics of the manufactured materials vary different manufacturers may differ in many ways.
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 found wide application in walls and roofs, as well as in elements of auxiliary structures: canopies, kiosks, fences of parks and bridges, balconies, flights of stairs and etc.
In the cold enclosures of 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 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 accepted in the USA and Europe. The assortment of profile sheets made of vinyl plastic (Merly company) and plexiglass (I-C-I 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, predominantly single-layer domes are used, while in countries with colder climates (Sweden, Finland, etc.) - two-layer ones with an air gap and a special device for draining condensate, made in the form of a small gutter along 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 capable of competing with similar designs 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 air humidity. 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 on the long sides on V-shaped spacers and joined at the top using metal overlays with mastic.
In the USSR, fiberglass was found in building structures very limited use (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, the total area of light openings filled with translucent structures is 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. For 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, having increased rigidity, better thermal properties and requiring minimum flow metal
The low weight of such structures allows the use of elements of considerable size, but their span, as well as corrugated sheets, is limited by maximum permissible deflections and some technological difficulties (the need for large-sized pressing 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 the 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 greater number of technological operations compared to solid-molded panels, which makes their production more complex, as well as the connection of the skins with the ribs less reliable than in solid-molded panels.
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 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 of solidly molded panels is also the single-stage process and increased reliability of connecting the thin ribs of the middle layer with the skins.
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 ways. Panels with a wavy middle layer are relatively easy to manufacture and have good lighting properties. However, the height of such panels is limited maximum dimensions waves
(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
worked on a number of interesting solutions for skylights made of fiberglass and plexiglass, and also carried out experimental projects.
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 works better than a flat panel for static loads, and its outline helps better removal 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).
Rooflights 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. So far in the USSR, only domes made of organic glass have found practical use 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 their better cleaning and rainwater discharge.
In the same building, a different structure was used above the winter garden, which consists of triangular packages glued together from two flat sheets organic glass, laid according to steel frame spherical shape. 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. The warm air that accumulates in the space under the dome prevents the formation of condensation on the inner surface of the dome.
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 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 support cups have inclined edges.
Rod and others 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 exhaust pipe 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 load-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, of stainless steel - in months, similar structures made of fiberglass are operated without damage for years. 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 m, 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.
