grupoavigase.com/includes/239/5092-chico-busca-chico.php Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect.
We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. In a facade, polymers have an effect on, for example, humidity, thermal balance, lighting or energy generation. According to research, a low level of technology in a building, i. The exact level of savings is based on the dimensions of the facade, its support and connection points and the supporting structure required.
Economic and ecological benefits are then combined. Optimised functional performance. Needing less energy to run the building might therefore be more effective than the savings realised through other measures. When used for insulation and energy generation in a building envelope, transparent and translucent polymers have an especially positive effect on the overall LCA. In this situation, the facade has the task of, on the one hand, tapping additional energy sources for the building e.
With polymers in the facade like with glazing it is therefore the g- and U-values that need to be adapted. On the other hand, polymers generally offer good g-values, which means that the higher passive solar energy gains can reduce the energy consumption. Membranes and foils in pneumatic structures must be investigated particularly carefully because this is where an appropriate U-value can only be achieved through the permanent use of energy e.
This means that the technical performance of the material e. Loadbearing structure and form Structural systems Geometry of lightweight surface structures Tensile surface structures Detailed design aspects Calculations Testing and approval Quality control and industrial safety. Building with foil Cushion lay-up and form Details Air supplies for pneumatic structures Safety of cushion structures Mechanically prestressed foil Cable net support systems.
Building with textile membranes Elements of the construction Seams Linear supports Edges Corner details High and low points. Complex building envelopes The envelope design brief Special aspects of foil and membrane designs Combinations of polymer and glass. Facades and pitched roofs are the principal applications for transparent, translucent or opaque polymer sheets. They are also suitable as internal partitions, for shielding electrical equipment alongside railway facilities or for balustrade infill panels.
The facade panels in everyday use can be made from brittle thermoplastics or fibre-reinforced polymers or other composites such as mineral boards. All these sheets are available in solid or hollow variations, which has an effect on the details.
Fire Testing. This chapter is distributed under the terms of the Creative Commons Attribution 3. Clipping is a handy way to collect important slides you want to go back to later. Polymers have several applications in construction industry. Cheng, Hercules Incorporated. Here, also lignin could play an important role in the future: Mostly used for energetic issues, it could now find application as a mechanical alternative for improved insulations. Electrochemical biosensors have gained ever-increasing acceptance in the field of medical diagnostics, health care, environmental monitoring, and food safety due to high sensitivity, specificity, and ability for real-time analysis coupled with speed and low cost and polymers are promising candidates that can facilitate a new generation of biosensors [ 1 - 7 ].
In principle, sheets can be used to build both watertight envelopes and also facing leaves with a ventilation cavity. Forms of construction based on polymer sheets sometimes borrow details such as point fixings or elastomeric strips from glass construction because there is a lack of details designed specifically for polymers. But in contrast to brittle glass, such elaborate measures are actually unnecessary. Compared with glass, polymer sheets are relatively easy to drill and cut to size.
Especially interesting here is the option of being able to incorporate the connection details into the sheets themselves during production. One essential difference when compared with glass or metal is that polymer sheets are not diffusion-resistant. The associated risk of condensation should be dealt with by construction measures such as a ventilation cavity. Sheets made from solid or fibre-reinforced polymers are generally between 3 and 7 mm thick. They are usually produced in large formats and only cut to size in the course of the final erection on site. The cut edges of fibre-reinforced polymers should be sealed afterwards.
Fixing Outer envelopes that serve merely as protection against the weather and for appearance purposes can be relatively straightforward forms of construction. The sheets can be bolted, screwed or riveted to the supporting framework Figs. Owing to the lower elastic modulus of the material, it is in many cases unnecessary to include expansion joints and elongated holes, especially with corrugated sheets, because the restraint stresses due to thermal movements are comparatively small Fig.
Joints between flat panels can often be simply overlapped and, like with panes of glass, the sheets laid on elastomeric strips Fig. Apart from that, the forms of construction can be built watertight. The supporting construction required is, however, more involved than with other methods of fixing.
Special fixing systems are worth considering for facades with a ventilation cavity; such systems are not visible from outside Fig. This solution protects the edges of the sheets against mechanical damage and in the case of fibre-reinforced polymers prevents the exposed edges from absorbing water.
Point fixings are very suitable in principle and their details are simpler than with glass because the holes are much easier to drill Fig. It is also possible to embed threaded sockets in the sheets to ease the fixing to the supporting framework Fig. Waterproofing Solid polymer sheets are generally not designed to be watertight, but instead make use of open drained joints.
Sheets that must be supported without restraint require relatively wide joints in order to accommodate the large movements of the polymer as a result of temperature fluctuations. Silicone sealants are therefore mostly unsuitable for polymer sheets. One simple option for a horizontal joint design is to overlap the sheets or to use preformed sealing strips Figs. Vertical joints can also be designed with preformed sealing or cover elements Figs. Screws and bolts with elastomeric sealing washers are required to achieve a watertight envelope.
They are suspended from the supporting construction via their webs, the vertical joints are sealed by way of a built-in overlap. The fixing and jointing methods for twin- and multi-wall sheets are more complicated than those for solid sheets because of the more complex geometries and the thin walls involved. This is especially true when the thermal insulation properties of the sheets must be retained by avoiding open joints or penetrations. There are limits to the widths of twin- and multiwall sheets that can be produced, but they can be produced in any length subject only to transport restrictions.
They are simply lined up side by side to form facades. Butt-jointed twinand multi-wall sheets do not result in satisfactory results because either the thermal insulation effect is interrupted or it is impossible to create a watertight joint Fig. Integral joints or special connecting sections have proved advantageous. Individual details have to be developed for corners as well as the top and bottom edges of sheets, although preformed corner and edge trims are available for certain products Fig. Metal connecting parts attached with adhesive a Plate b Angle Building in plates or perforated sheet metal to optimise a connection, with rovings looped through perforations a Axonometric view b Section Proprietary fittings for building into fibrereinforced polymers.
Fibre-reinforced polymer Lug made from thin sheet steel Long fibres rovings , looped through perforations Normal planar fibre reinforcement. Glued joints Steel lugs and angles can also be attached with adhesive as an alternative to using built-in components Fig. High forces can be transferred with a sufficiently large adhesive joint. Built-in metal fittings Built-in fittings made from steel, stainless steel or aluminium are useful for individual connections with a concentrated load transfer.
The coefficients of thermal expansion of the laminate and the built-in part should be compatible with each other in order to minimise restraint stresses. The thermal expansion coefficients for fibrereinforced polymers vary over a wide range depending on type of fibre and laminate lay-up, which is why it is not possible to make any global recommendations regarding materials. The very low coefficient of thermal expansion of CFRP makes it less suitable for combining with metals. Metal lugs and plates should be kept as thin as possible in order to minimise the disruption to the laminate lay-up Fig.
Perforated sheet metal enables a better penetration of the polymer during production and the long fibres rovings can also be looped through the perforations, which increases the load-carrying capacity yet further.
Screws and threaded sleeves can be anchored in the laminate with prefabricated built-in components. As with lugs and plates, thin perforated sheet metal produces the best results Figs. Large built-in fittings are also possible with sandwich elements. They are positioned within the core material.
Sandwich elements are responsible for two main functions when building with fibre-reinforced polymers: increasing the load-carrying capacity beyond that of a thin laminate, and thermal insulation. A design without joints is therefore desirable in order to avoid degrading E 2.
Polymer materials account for the highest growth area in construction materials. In basic terms, polymers are very long molecules typically made up of many. Apr 11, Polymer materials account for the highest growth area in construction materials. Well-established applications of polymers in construction.
One option here is to provide a loose tongue and groove joint for the core and subsequently laminate over the joints Fig. During construction, the forces are transferred exclusively via the joint in the core material, which calls for the use of a material with a suitable loadbearing capacity, e. Once the joint has been finished, the facing plies of fibre-reinforced polymer are continuous and the joint is concealed, the sandwich element essentially continuous.
It may be necessary, however, to add a final ply over the entire structure in order to achieve an adequate load-carrying capacity. Bolted joints Sandwich elements can also be connected via bolts or screws where economic criteria dictate or where the construction is not permanent. Local reinforcement is necessary to cope with the stress concentration at the joint, which usually results in a lower loadbearing capacity and a lower thermal insulation value, however.
A stepped joint Fig. The bolted connection can be strengthened with an integral steel collar. Alternatively, an integral flange can be formed in the sandwich element Fig.
Facing ply made from fibre-reinforced polymer Rigid foam core Loose tongue made from rigid foam, glued in place Facing ply laminated in situ after joining elements. Large format built-in steel parts Large-format built-in parts can replace the core material locally in a sandwich element, which achieves an increase in the load-carrying capacity but without this being visible from the outside. For example, the roof shell to the Itzhak Rabin Center is made from sandwich elements with integral steel trays for connecting to the columns Fig.
The first step in the production is to assemble all the fibre plies, the rigid foam core and the built-in parts. The entire cross-section is then impregnated with the polymer using the resin infusion method in a second step Fig. On site the finished E 2. As the final shape of the cushion depends not only on its cutting pattern, but also on the elongation of the material itself, it is essential to make sure that there is sufficient clearance between the underside of each cushion and the primary loadbearing structure or other components.
This is because the sag of the cushion can be expected to increase over time due to the creep of the material caused by constant, sometimes high, loading. This section deals mainly with the construction details for air-filled cushion assemblies. Movable central layer a Moved by repositioning b Moved by elastic elongation E 3.
In contrast to coated woven fabrics, welding foil materials results in a homogeneous joint. The tensile strength and waterproofing quality at the seam could therefore be achieved, in theory, with a welded seam no wider than the thickness of the material. The prerequisite for this, however, is that the areas adjacent to the seam are perfectly formed. Foil materials are clamped along their edges or held in place by edge cables or webbing belts in pockets — all similar details to those of textile membranes.
But as foil is employed mainly for pneumatic cushion designs, rigid edges with clamping sections represent the commonest solutions. These sections are generally extruded, anodised aluminium products. Sections with rough surface finishes or sharp edges or affected by galvanic corrosion must be avoided at all costs because such defects can cause mechanical damage to the foil and changes in its microstructure. Clamping details can include strips made from elastomeric materials such as ethylene propylene diene monomer rubber EPDM laid between the foil and the metal clamping sections in order to protect the foil against all mechanical, chemical and thermal actions.
Such elastomers can be integrated directly into clamping elements in the form of factory-fitted polymer edge beads Fig. The clamping along the edges of foil cushions can satisfy several constructional, technical and building physics requirements at the same time:. Many different edge clamping sections are available for ETFE cushions, which undergo constant development by their manufacturers so that all the functions listed above can be properly covered and integrated. We can distinguish between a number of different types of edge clamp.
When using a thermally insulated clamping section, it is important to remember that the insulating value of the cushion decreases severely towards its edges and more condensation will collect on the underside of the cushion here. Such edge details should therefore include a drainage channel below the clamping section Fig. Condensation is less of a problem where the upper and lower layer are clamped separately. Simple edge clamp details In principle, we distinguish between clamping with simple flat bars Fig.
With the former detail, the keder is fitted behind the bar itself and therefore the fixing screws or bolts have to pass through holes in the edge of the foil. With extruded aluminium sections, the keder can be held in place in front of the fasteners, which avoids having to penetrate the foil, and therefore damaging it. Edge clamp detail with factory-fitted polymer edge bead In this type of detail, the fabricated foil with its welded keder is already threaded into a polymer edge bead usually made from EPDM at the factory, and the polymer edge bead itself later clamped in a two-part aluminium section Fig.
This type of edge clamp detail has a number of advantages over the simple edge clamp described above:. Heating causes plastic deformation of the foil, which results in a state of stress equilibrium. At open corners the keder is stopped short of the corner; the welded seam continues, however, as far as the corner itself and therefore ensures that the foil remains watertight Fig.
Edge clamp detail with erection aid Separate clamping bars can be integrated into the clamping section in order to simplify the installation of the cushions. These separate bars are clipped into the sections attached to the loadbearing structure without the need for any screws or bolts and are either fitted directly to the keder or clamped to a polymer edge bead Fig.
Once all the sections on one side. As the angle at the corner of a foil cushion becomes more acute, so it becomes more and more difficult to achieve a homogeneous transfer of the stresses in the surface to the corner and thus avoid wrinkles and creases. In the case of very acute angles, the keder in the edge should be turned around the corner with a polygonal or rounded form. Sharp corners are in practice sometimes pretensioned and heated. Ring D-ring Custom corner plate Webbing belt along edge of membrane Retaining bar Slotted corner plate Pocket for cable along edge of membrane Edge cable Corner plate Webbing belt Threaded fitting in sleeve Spherical washer Tie bar.
Wherever two flexible membrane edges meet at a corner, the forces in the edge cables must be anchored and transferred to the loadbearing structure or foundations in the direction of the resultant reaction. The characteristics of corner details are therefore essentially determined by the design of the membrane edge. For simplicity, the following descriptions are based on a typical corner detail with two edge cables in order to present the different forms of construction.
A membrane is always doubled at a corner in order to handle the unavoidable stress peaks, which can occur because the membrane cannot dissipate overstresses within the short span at the gusset, neither through elongation nor through racking of the weave of the fabric. The additional layer of membrane is permanently welded or stitched to the main membrane and fitted around the corner in an arc. Edge cable pockets should be widened at the corners so that they do not tear.
Corner plates are usually made from galvanised steel or stainless steel because anti-corrosion coatings on steel are inevitably damaged by tensioning equipment and movements of the cables. Corner details for webbing belt edges. In contrast to steel cables, webbing belts are not sensitive to buckling and so can be fitted to corner details at very tight radii.
This enables very compact details to be designed, with a steel ring or a custom corner plate with slits to be stitched into the corner during fabrication of. Open slits can also be provided where later replacement or later fitting of the corner plates is desirable Fig. Rounding off all edges and corners of custom plates is vital. In some circumstances a second hole must be provided for the tensioning equipment in addition to the hole for the actual fixing so that erection and tensioning of the corner can be carried out.
Corner details with cable connections. Both the membrane and the edge cables must be connected to the corner plate in this type of corner detail. Open membrane corners At open membrane corners the membrane is not connected to the corner plate directly, but rather via the edge cables and, if necessary, ratchet straps. With this type of detail, the membrane is cut around the corner plate in an arc shape and reinforced by a second layer of material in this zone.
The tangential forces parallel to the edge cable at an open membrane corner must be transferred separately to the corner plate in order to prevent slippage of the membrane at the corner, especially during erection. This is achieved in most cases by stitching webbing belts into the membrane pocket which are tensioned against the corner. Equalising and unifying interior wall surface temperatures to match interior air temperature E 5. Objective and effect of thermal insulation measures Why do we actually try to reduce the heat transfer through the building envelope?
The reasons are varied and go well beyond the alleged primary inducement of saving energy, and many are related to each other Fig. The physiological functions of the human body serve as the starting point for creating a sufficiently hygienic and comfortable interior climate. Various areas are touched on and influenced within the scope of any thermal insulation measure Fig.
These effects must be addressed and checked. At the same time, there are many potential conflicts to be overcome Fig. As the governing external conditions acting on a building are of a dynamic nature, a purely static approach to thermal insulation measures is inappropriate, even though this type of approach has been used hitherto in all the relevant standards and regulations. Dynamic interactions between exterior, building envelope and interior — and hence consequences for the heat flow — result from, in particular, solar energy gains via translucent and transparent areas of the building envelope and the heat storage properties of building components thermal mass.
The development of efficient building envelopes using foil and membrane materials to provide protection from the climate requires the consideration of diverse aspects that are perhaps unnecessary when working with conventional building materials and forms of construction. In conjunction with the further specific characteristics of these extremely thin and flexible materials, these special aspects in turn result in unique solutions to many issues, only some of which are presented here, with no claim to be exhaustive.
Thermal performance is an important aspect for a building envelope and, as foil and membrane materials for reasons of their minimal thickness alone 0. This is the case with air-filled pneumatic membrane cushion structures in particular, but with tensile surface structures the normal answer is to provide additional thermal insulation. Air-filled cushion designs are frequently chosen not for their structural and constructional benefits, but rather because their intrinsic multi-layer construction leads to a vast improvement in the thermal insulation properties.
When transparency, i. As Fig. Consequently, this represents an improvement Fig. Nonetheless, the cushion edge details are still important for the heat transfer through a building envelope composed of membrane cushions. Besides the thermal insulation quality of the clamping frame detail e. In an opaque envelope construction with comparatively heavyweight building materials and, possibly, thermal insulation as well, it is conduction that is the dominant component in the total heat transfer.
By comparison, in permeable, lightweight, multi-layer designs, i. The thermal conductivities of the materials used, as with all thin, planar polymer materials, are practically irrelevant because of the minimal thickness of each material and its position perpendicular to the heat flow. The large proportion of heat transfer by way of radiation leads to a differentiated behaviour of the envelope in relation to the radiation environment. It is this behaviour that must be considered when optimising the energy efficiency of the design Fig.
A considerable energy transfer via radiation can be expected in the absence of clouds to attenuate the radiation effect, i. As a result, the temperature of certain exposed surfaces, for example, can drop well below that of the surroundings. The condensation that may occur must be taken into account when designing the envelope. Radiation longwave through absorption Radiated heat due to temperature of cushion depending on surface emissivity, possibly reflection of radiation low E.
Critical here is the Uf-value, i. One fundamental frame optimisation option that can be used for membrane cushions is to separate the individual layers and clamp them separately Fig. The potential im-. However, this solution involves considerably more design and construction input two clamping elements, airtightness, protection from weather during erection , which inevitably results in higher costs.
The standard variation of a factory-welded cushion with a common clamping arrangement, fixed directly to the. The headquarters of this Danish manufacturer of glass fibre-reinforced polymers GFRP seems to form a gentle hill in the flat landscape. Development, production and offices are combined here under one roof, with an integral high-bay racking warehouse defining the maximum height of the building.
All the functional areas of the production are grouped around this central element. Offices, development and marketing are housed in the three storeys on the east side of the building, separated from the production bay by glazing, which permits a visual link between the two areas. At the same time these atria ensure that plenty of daylight is distributed throughout the interior. The outer leaf consists of vapour-tight sandwich panels clad with GFRP planks.
Overlapping joints ensure that this outer leaf, in front of a ventilation cavity, remains rainproof. Specially formed GFRP sections were used for the window sills and window frames as well. The latter are very narrow on elevation yet still achieve a good insulation value. Both the pultruded sections and the facade panels are produced with a transparent resin so that the internal fibre reinforcement remains visible and lends the components a certain depth.
The all-glass facades to the three atria also make use of GFRP sections, which are glued directly to the panes of glass. The prefabricated elements are merely bolted together and to the supporting structure underneath. The rigid adhesive joints enable the glass to be used for carrying the loads, which means that the frame dimensions could be much smaller than those of an aluminium facade. This house and office belonging to the architects is located in the old quarter of Dachau. Almost half of the spacious open area on the eastern side of a building is sheltered beneath the long branches of a year-old lime tree.
This natural monument forms the focal point of this innercity square and makes this site unique. All the habitable rooms of the building therefore face east. The view of the tree is the chief theme and the facade, too, reflects this. Photographs of the tree were projected onto the external leaf and so the contours of the tree seem to embrace the entire building. The translucent envelope made from glass fibrereinforced polymer makes this possible. The tree motif plotted on special paper is laminated into the manually laminated panels.
The impregnation with synthetic resin means that the motif remains visible even though it is coated with the final layer of GFRP. Certain lighting conditions reveal the supporting framework behind, too. The multi-layer construction of the facade becomes visible, thus achieving a spatial effect and the lightness desired by the architects.
The colour and form of the set-back top storey represent a stark contrast to the rest of the building even though the same materials have been used. Paint with a high pigment content was mixed into the synthetic resin to achieve the muted aubergine colouring. The individual panels have rounded arrises and corners, and include flanges that are overlapped and bolted together at the joints.
The ensuing pattern of the joints lends the facade a certain structure. The negative moulds required for the individual GFRP elements were produced from polystyrene and polyurethane foam in unpretentious manual work with a file! The building stands as a clear contrast to its surroundings without dominating them, and allows the old tree to take the limelight in this urban setting.
Neydens is only a village on the French border with Switzerland, about 10 km south of Geneva. Nevertheless, it is the location of a major new leisure centre with swimming pools, outdoor areas, wellness facilities with sauna and Turkish bath, a fitness centre with climbing wall, plus shopping mall, hotel, restaurants and bars — a total area of approx. The architects restricted the volume of the complex and added green roofs so that the leisure centre would not dominate the charming landscape of this area. The enclosure for the water park with its several pools is particularly worthy of note.
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