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Материалы, которые используются для структурных целей следует несколько требований. В большинстве случаев важно, что они должны быть жесткий, прочный, пожар устойчивы и легко крепится вместе.Наиболее часто используемые материалы – сталь, бетон, камень, дерево и кирпич. Они отличаются в твердости, прочности и огнестойкости.Древесина является наиболее древним конструкционный материал. Это легкие, дешевые и легко работать. Но древесина имеет определенные недостатки: он горит и разлагается.Камень принадлежит к одному из старейших строительных материалов, используемых человеком. Это характерно для многих свойств. Они являются механическую прочность, плотность, пористость, звуко- и теплоизоляцию и огнестойкости.Кирпичи были известны многие тысячи лет назад. Они являются примерами искусственных строительных материалов.Бетон считается одним из самых важных строительных материалов. Бетон-смесь цемента, песка, щебня, камня и воды.Сталь вступают в общего пользования с развитием промышленности. Его производство требует специального оборудования и квалифицированных кадров.Пластмассы объединить все прекрасные характеристики строительного материала с Хорошие электроизоляционные свойства. Это не удивительно, что архитекторы и инженеры обратились к ним добавить красоты в современных домах и офисах.Все строительные материалы делятся на три основные группы:1. Основные строительные материалы, такие как искусственные камни, деревообрабатывающая и металлов.2. Переплетные материалы например, извести, гипса и цемента.3. среднее или вспомогательные материалы, которые используются для внутренних частей зданий.Мы используем много строительных материалов для несущих конструкций. Вяжущие материалы используются для изготовления искусственного камня и объединения различных плоскостях. Для внутренней отделки зданий мы используем вторичные материалы.Естественные строительные материалы – камень, песок, известь и древесины. Цемент, керамических изделий и бетона являются примерами искусственных строительных материалов.2 древесиныДревесина является наиболее древним конструкционный материал. По сравнению с стальной стержень, легче, дешевле, легче работать и его механических свойств являются хорошими. С другой стороны древесина имеет определенные недостатки. Во-первых он горит и поэтому неподобающе для огнеупорных зданий. Во-вторых она убывает.В настоящее время огромное количество древесины используется для огромного числа целей. В здании древесины используется тоже.Древесина — это имя применяется для вырезать материал, получаемый из деревьев. Пиломатериалы, используемые для целей строительства делится на две группы: хвойные и лиственные породы. Лиственных пород, главным образом используются для декоративных целей, а обшивка, Шпонирование мебель и некоторые из них выбираются для конструктивного использования из-за их высокую прочность и долговечность. В современном строительстве лесоматериалов часто используется для оконных и дверных рам, настил, заборы и ворота, настенные тарелки, для временных зданий и неокрашенных внутреннего дерева.Timber cannot be used for either carpenters' or joiners' work immediately it has been felled because of the large amount of sap which it contains. Elimination of this moisture increases the strength, durability and resilience of timber.3 StoneStone has been used as a structural material since the earliest days.Almost all famous buildings of classic times, of the medieval andRenaissance periods and of the 18th and early 19th centuries were erected of stone masonry. In some places stone was used because of the scarcity of timber but in other places stone was preferred because of its durability.The stones which are usually used for masonry work are as follows:1. Granite is very hard, strong and durable. It is used particularly for basements, base courses, columns and steps and for the entire facades. Its colour may be grey, yellow, pink or deep red.2. Sandstone is composed of grains of sand or quarts cemented together. Sandstones form one of the most valuable materials. The durability of sandstones depends very largely upon the cementing material. Thus, there are different kinds of sandstones. Many sandstones are exceptionally hard and are selected for steps, sills, etc. It is an excellent material for concrete aggregate.3. Marble is a crystalline stone chiefly used for decorative purposes. White and black marbles are used for ornamental decoration where the beauty of the marble is shown to its best advantage.4 Metals and concreteAll metals are divided into ferrous metals and non-ferrous metals. Ferrous metals include iron, steel and its alloys. Non-ferrous metals are metals and alloys the main component of which is not iron but some other good element. Metals, in general, and especially ferrous metals are of good importance in variations.Metals possess the following properties:1. All metals have specific metallic lustre.2. They can be forged.3. Metals can be pulled.4. All metals except mercury are hard substances.5. They can be melted.6. In general, metals are good conductors of electricity.These characteristics are possessed by all metals but the metals themselves differ from one another. Steel and cast iron are referred to the group of ferrous metals. Cast iron is the cheapest of the ferrous metals. It is chiefly used in building for compressed members of construction, as the supporting members. When an engineer designs a steelwork he must carefully consider that the steel frame and every part of it should safely carry all the loads imposed upon it. The steel framework must be carefully hidden in walls, floors and partitions. It is steel and metal that is employed as reinforcement in modern ferroconcrete structures. In the curriculum of the Institute there is a special course on metal structures.Steel. There are different kinds of steel. Alloyed steel or special steelis corrosion-resistant steel. This kind of steel is widely used in building. Stainless steel is also corrosion-resistant steel. It is used for cutlery, furnace parts, chemical plant equipment, valves, ball-bearings, etc.Non-ferrous metals. Non-ferrous metals have the following characteristics: high electric and heat conductivity, high corrosion resistance, non-magnetic qualities, light weight.Alumunium. This is the oldest and best known light metal. It is used in aircraft, automobile, chemical and some other industries.Copper. Copper is the best conductor of electricity. There are different alloys with copper. An alloy of copper and tin is called bronze. This metal is often used for making various ornaments.Buildings of reinforced concrete may be constructed with load-bearing walls or with a skeleton frame. According to the first method, the exterior walls are designed of sufficient strength to carry the loads of the girders, beams, floors and roofs which rest on them. The interior supports may consist also of load-bearing walls or of columns, but this method does not utilize the full potentialities of concrete. By the second method, the floors and roofs rest directly on exterior and interior columns or are carried on beams and girders which, in turn, rest on the columns. The walls and partitions are simple enclosures of brick or reinforced concrete supported by the beams and girders. Most concrete buildings of any size are now designed according to this second or skeleton frame method.5 Cement: man's miracle mix
One of man's oldest building materials is finding its way into a lot of new places these days. Concrete, first discovered by the Romans, is now more widely used in construction than all other materials together.
The magic ingredient that makes concrete possible is cement, about which according to one expert more has been learnt in the past three decades than in the preceding 2000 years. Concrete is a synthetic stone which can be formed while soft into practically any shape the builder wants. Portland cement mixed with water is the paste that binds sand, gravel, clinker into an artificial rock that becomes harder as the years pass. Portland cement does not come from a place of that name; it was called Portland because Joseph Aspdin, the English builder who invented the first dependable, scientifically made cement about 1824, thought it resembled the rock excavated on the Isle of Portland on the Dorset Coast.
What's so new about cement after all these years? Several things. One item is "squeezed" concrete known technically as pre-stressed concrete. By giving concrete a big squeeze after it has hardened, builders can increase its elasticity ten times, so that it will bend under a heavy load without breaking. This is important in building bridges, viaducts and floors of large buildings.
The simplest way to pre-stress concrete is to put steel wires or rods in the concrete when it is poured.
An unusual American use of reinforced concrete is the floating highway bridge across Lake Washington. The depth of the lake made piers too expensive, so engineers built the bridge on hollow concrete pontoons anchored in place by steel cables. It is the longest pontoon bridge structure on Earth.
Until recently the aim of engineers was to make concrete with as few bubbles as possible. Now they have come up with a new concrete that has millions microscopic bubbles per cubic foot. It is made by adding an agent which foams to form the bubbles when the concrete is mixed. This concrete doesn't crack when freezing. The first "air bubble" roads were built many years ago. They have stood up under winter freezes so well that today this concrete is used for new road construction.
Another discovery is "soil cement". Several years ago road builders lacking funds found that they could mix cement with soil on the site of the road, wet it and compact it, then cover it with bitumen. The first road they built is still carrying traffic. There are miles of soil-cement secondary roads and streets today. Construction goes so fast that with modern equipment a road builder can complete a mile of soil cement road in one day.
Scientists are working on research into the behavior of cement and concrete under all kinds of conditions. Collaborating with engineers they are developing new ways
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