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土木工程英语翻译2 托福口语怎么练
The history of civil engineering Another advance in steel construction（结构） is the method of fastening together（连在一起） the beams. For many years the standard method was riveting. A rivet is a bolt with a head that looks like a blunt screw（圆头螺丝钉） without threads（螺纹）. It is heated, placed in holes through the pieces of steel（钢构件）, and a cond head is formed at the other end by hammering（锤击）it to hold it in place（固定就位）. Riveting has now largely been replaced by welding, the joining together of pieces of ste Fundamentally, engineering is an end-product-oriented discipline that is innovative, cost-conscious and mindful of human factors. It is concerned with the creation of new entities, devices or methods of solution: a new process, a new material, an improved power source, a more efficient arrangement of tasks to aomplish a desired goal or a new structure. Engineering is also more often than not concerned with obtaining economical solutions. And, finally, human safety is always a key consideration.Engineering is concerned with the u of abstract scientific ways of thinking and of defining real world problems. The u of idealizations and development of procedures for establishing bounds
dcewithin which behavior can be ascertained are part of the process.
Many problems, by their very nature, can’t be fully described—even after the fact, much less at the outt. Yet aeptable engineering solutions to the problems must be found which satisfy the defined needs. Engineering, then, frequently concerns the determination of possible solutions within a context of limited data. Intuition or judgment is a key factor in establishing possible alternative strategies, process, or solutions. And this, too, is all a part of engineering.
Civil engineering is one of the most diver branches of engineering. The civil engineer plans, designs, constructs, and maintains a large variety of structures and facilities for public, mercial and industrial u. The structures include residential, office, and factory buildings; highways, railways, airports, tunnels, bridges, harbors, channels, and pipelines. They also include many other facilities that are a part of the transportation systems of most countries, as well as wage and waste disposal systems that add to our convenience and safeguard our health.The term “civil engineer” did not e into u until ab
out 1750, when John Smeaton, the builder of famous Eddystone lighthou near Plymouth, England, is said to have begun calling himlf a “civil engineer” to distinguish himlf from the military engineers of his time. However, the profession is as old as civilization.
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In ancient Egypt the simplest mechanical principles and devices were ud to construct many temples and pyramids that are still standing, including the great pyramid at Giza and the temple of Amon-Ra at Karnak. The great pyramid, 481 feet(146.6 meters)high, is made of 2.25 million stone blocks having an average weight of more than 1.5tons (1.4 metric tons). Great numbers of men were ud in the construction of such monuments. The Egyptians also made obelisks by cutting huge blocks of stone, some weighing as much as 1000 tons (900 metric tons). Cutting tools of hard bronze were ud.The Egyptians built cauways and roads for transporting stone from the quarries to the Nile. The large blocks of stone that were erected by the Egyptians were moved by using levers, inclined planes, rollers, and sledges.The Egyptians were primarily interested in the know-how of construction; They had very little interest in why-for of u .In contrast, t
he Greeks made great strides in introducing theory into engineering problems during the 6th to 3rd centuries B.C. They developed an abstract knowledge of lines, angles, surfaces, and solids rather than referring to specific objects. The geometric ba for Greek building construction included figures such as the square, rectangle, and triangle.
The Greek architekton was usually the designer, as well as the builder, of architectural and engineering masterpieces. He was an architect and engineer. Craftsmen, masons, and sculptors worked under his supervision. In the classical period of Greece all important buildings were built of limestone or marble; the Parthenon, for example, was built of marble.
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The principal construction materials The principal construction materials of earlier times were wood and masonry-brick, stone, or tile, and similar materials. The cours or layers（砖层）were bound together with mortar or bitumen, a tarlike substance, or some other binding agent. The Greeks and Romans sometimes ud iron rods or clamps to strengthen their building. The columns of the Parthenon in Athens（雅典的帕台农神庙）,
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for example, have holes drilled（钻孔） in them for iron bars that have now rusted away（锈蚀殆尽）. The Romans also ud a natural cement called pozzolana, made from volcanic ash, that became as hard as stone under water. Both steel and cement, the two most important construction materials of modern times, were introduced（推广） in the nieenth century. Steel, basically an alloy of iron （铁合金）and a small amount of carbon, had been made up to that time（到那个时候） by a laborious（繁复的） process that restricted it to such special us as sword blades（刀刃）. After the invention of the Besmer process （贝塞麦炼钢法）in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile strength; that is, it does not lo its strength when it is under a calculated degree (适当的) of tension, a force which, as we have en, tends to （往往）pull apart many materials. New alloys have further incread the strength of steel and eliminated some of its problems, such as fatigue, which is a tendency for it to weaken as a result of continual changes in stress（连续的应力变化）.Modern cement, called Portland cement, was invented in 1824. It is a mixture of limestone（石灰石） and clay, which is heated and then ground into a powder（磨成粉末）
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. It is mixed at or near the construction site （施工现场）with sand, aggregate (small stones, crushed rock, or gravel), and water to make concrete. Different proportions of the ingredients （配料）produce concrete with different strength and weight. Concrete is very versatile; it can be poured, pumped, or even sprayed into （喷射成）all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under pression. Thus, the two substances plement each other（互补）.They also plement each other in another way: they have almost the same rate of contraction and expansion. They therefore can work together in situations where（在…情况下） both pression and tension are factors（主要因素）. Steel rods（钢筋） are embedded in（埋入）concrete to make reinforced concrete in concrete beams or structures where tension will develop（出现）. Concrete and steel also form such a strong bond - the force that unites（粘合） them - that the steel cannot
slip（滑移） with the concrete. Still（还有） another advantage is that steel does not rust in concrete. Acid（酸） corrodes steel, whereas concrete has an alkaline chemical reaction, the opposite of acid. yw
The adoption of structural steel and reinforced concrete caud major changes in traditional construction practices（施工作业）. It was no longer necessary to u thick walls of stone or brick for multistory buildings, and it became much simpler to build fire-resistant floors（防火地面）. Both the changes rved to（有利于） reduce the cost of construction. It also became possible to erect（建造）buildings with greater heights and longer spans.Since the weight of modern structures is carried（承受） by the steel or concrete frame, the walls do not support the building. They have bee curtain walls, which keep out the weather and let in light. In the earlier steel or concrete frame building, the curtain walls were generally made of masonry; they had the solid look of bearing walls（承重墙）. Today, however, curtain walls are often made of lightweight materials such as glass, aluminum, or plastic, in various binations.
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