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Nanotechnolody's for real in the building industry
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Nanotechnology is sometimes seen as all hype, with little real-world application. But nanomaterials are already all around us. Take the buildings that we live and work in, for instance. You will find nanotechnology used to create stronger steel, self-cleaning glass, solar-collecting fabrics, and even smog-eating concrete. And not only are these nanomaterials present in our buildings, they are making them better places to live and work.
Self-cleaning glass has a nanoparticle coating dirt can't stick to, eliminating the need for expensive and dangerous manual window washing on tall buildings. Solar-collecting fabric is the first of a new wave of building components that convert solar radiation into electricity. That means no more applying unattractive solar panels to the roof, but instead integrating energy production into building facades. Nanocomposite steel is more corrosion resistant than conventional steel, and can reduce installation costs by up to 50%. And the quantity required to make a building may be up to 40% less than conventional steel. Smog-eating concrete is produced by applying a nanolayer of titanium dioxide to concrete, which triggers a catalytic reaction that destroys many pollutants in contact with the surface. At the very least, these materials reduce building maintenance costs, leaving more money for other improvements, and they can help clean up the environment. They can reduce energy costs as well. And for every nanomaterial available today, there are approximately seventy more in research and development, meaning that building construction and architecture are in for some big changes thanks to small technology.
• TAPESCRIPT 7A
A HORIZONTAL SUPPORT
A beam is a structural component mainly working in bending through the agency of vertical forces and that transmits to the bearing points the loads that are applied to it. A beam is a lengthened and
Английский язык для студентов строительных специальностей
TAPESCRIPTS 337
horizontal support made of metal, wood, reinforced or prestressed concrete and whose section has been studied for a good bending strength. Beams are mainly subjected to bending moments and shearing forces. Simple beams are made up of only one piece, of a section calculated to withstand the strains that aim at making them bending. When the strains become too strong, reinforced beams or compound beams are then used. Beams rest:
—either on a bearing with restraint (cantilever) or are restrained at both ends (exceptional);
—either on a cantilever and are then presented as continuous beams to which have been added a number of extra articulations in order to free oneself of the consequences of the difference in level of the supports;
—either on two free bearings, free and restrained; they are independent or isostatic beams. These beams work on the positive bending moment in the middle of span and with simple shearing force on bearing;
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—either on several bearings (beam in continuity); they are continuous or hyperstatic beams. This type of beam bears on one hand a positive bending moment much weaker than an independent beam; but, on the other hand, when on bearing, it bears an important negative bending moment as well as the shearing force.
• TAPESCRIPT 7B
ROOF
The roof of a building often reflects the climate of the place in which the building is located since it protects the people in it from rain and sun. In dry countries the roof is flat and can be used as an outdoor room when the sun is not too hot. Where it often rains the roof usually slopes so that the wet can run off it, and where there are snowfalls, the roof slopes steeply so that the snow will slide off and not build up into a thick layer. A roof that slopes is called a pitched roof.
After a time people found it inconvenient to live in a house with sloping sides, so they built upright walls and laid big beams
called tie-beams across the top at regular distances from each other. Then they put up the triangular frameworks resting on the tie-beams. These triangles of beams are called trusses. A ridge-piece, purlins, and rafters were used to complete the skeleton of the roof.
In the Middle Ages the wooden frame of the roof was not hidden by a ceiling on the inside and was often richly decorated. To increase the effect of height and space the hammer-beam roof was designed. This had no tie-beams, but instead there were short beams sticking out from both walls, and to these beams other timbers called struts were fixed to support the main rafters.
The waterproof covering of a pitched roof is usually of tiles, slates, or shingles. Tiles are thin slabs of baked clay, generally red or brown in colour. Strips of wood called battens are fixed to the outside of the rafters, usually over sheets of weatherproof roofing-felt which help to keep out draughts and wind-blown snow. The tiles, shingles, or slates are then hung on by projecting pieces called nibs, or nailed or clipped to the battens in regular horizontal rows or courses. Flat roofs usually consist of boards covered with overlapping sheets of roofing felt coated with bitumen. When a roof has to cover a large space, steel trusses are used instead of wood. Large flat roofs may be made of reinforced concrete with a waterproof covering.
• TAPESCRIPT 8A
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