土木工程專業(yè)英語論文翻譯

1、建筑材料鋼的最嚴(yán)重缺點是它容易被氧化而需要被油漆或一些其他的適當(dāng)涂料保護。當(dāng)鋼被用于可能發(fā)生火災(zāi)環(huán)境時, 鋼應(yīng)該包圍在一些耐火的材料中, 例如石料或混凝土。通常，鋼的組合結(jié)構(gòu)不易被壓碎除非是在冶金成分不好，低溫的不利組合, 或空間壓力存在的情況下。建筑用鋁仍然不廣泛被在土木工程結(jié)構(gòu)中用,雖然它的使用正在穩(wěn)定地增加。藉著鋁合金作為一個適當(dāng)?shù)倪x擇和對其進行熱處理,可獲得各式各樣的強度特性。一些合金所展現(xiàn)的抗壓強度特性相似于鋼, 除線形彈性模量大約是7,000,000 牛/平方厘米，相當(dāng)于剛的三分之一。質(zhì)量輕和耐氧化是鋁的兩個主要優(yōu)點。因為它的特性對熱處理是非常敏感的,當(dāng)鉚接或焊接鋁的時候，一定要小

2、心仔細(xì)。一些技術(shù)已為制造預(yù)制鋁組合配件及形成若干的美麗的設(shè)計良好的外型結(jié)構(gòu)的鋁制結(jié)構(gòu)而發(fā)展起來。組合房屋配件制造的一般程序藉由螺栓連接，這似乎是利用建筑用鋁的最有前途的方法。加強和預(yù)應(yīng)力混凝土是主要的建筑材料。天然的水泥混凝土已經(jīng)被使用長達(dá)數(shù)世紀(jì)之久。現(xiàn)代的混凝土建筑興起于十九世紀(jì)中葉,盡管人造水泥被 Aspidin ，一個英國人于1825年申請了專利. 雖然一些建筑者和工程師在十九世紀(jì)后期用鋼筋混凝土作實驗, 但作為一種建筑材料它占統(tǒng)治地位是在二十世紀(jì)初期。后五十年鋼筋混凝土結(jié)構(gòu)設(shè)計和建筑得到迅速發(fā)展, 早期在法國的 Freyssinet 和比利時的 Magnel被大量使用。素混凝土作為建筑

3、材料有一個非常嚴(yán)重的缺點：就是它的抗拉強度非常有限, 只是它的抗壓強度的十分之一。素混凝土不僅受拉破壞是脆性破壞，而且受壓破壞也是在沒有多大變形預(yù)兆的情況下發(fā)生的準(zhǔn)脆性破壞。(當(dāng)然,在鋼筋混凝土建筑中,可以得到適當(dāng)?shù)难有?。只有進行適當(dāng)?shù)酿B(yǎng)護和合理的選擇并且摻加適當(dāng)?shù)幕旌咸旒觿?否則 霜凍破壞能嚴(yán)重的損害混凝土。在長期荷載作用下混凝土在選擇設(shè)計受壓情況方面要仔細(xì)考慮。在硬化的時候和它的早期養(yǎng)護下,混凝土收縮占主要地位, 因此需要添加適當(dāng)?shù)乇壤奶砑觿┒矣眠m當(dāng)?shù)慕ㄖ夹g(shù)來控制。藉由所有的這些可能的嚴(yán)重缺點，工程師已經(jīng)試著為各種實際結(jié)構(gòu)設(shè)計建立美麗的，持久的，和經(jīng)濟的鋼筋混凝土結(jié)構(gòu)。這是藉著設(shè)計

4、尺寸和鋼筋排列安排的謹(jǐn)慎選擇，和適當(dāng)?shù)乃嗟陌l(fā)展已經(jīng)趨于同步, 適當(dāng)添加劑混合比例, 混合配置, 而且養(yǎng)護技術(shù)和建筑方法，儀器的快速發(fā)展。混凝土具有多種用途，其組成材料廣泛可取，并且能非常方便地澆制成滿足強度及功能要求的形狀，同時，隨著新型預(yù)應(yīng)力混凝土、預(yù)制混凝土以及普通混凝土施工方法令人興奮的進一步改善和發(fā)展的潛力，這些因素綜合起來使得混凝土在絕大多數(shù)結(jié)構(gòu)中有著比其他材料更大的競爭力。在現(xiàn)代,藉由鋼和加強鋼筋的使用量在建筑結(jié)構(gòu)中的增加,木材在建筑期間主要地已經(jīng)被撤離到附屬的、暫時的和次要的結(jié)構(gòu)中使用,成為建筑材料的次要成員。然而, 現(xiàn)代的技術(shù)在最后六十年中已經(jīng)有使木材作為建筑材料恢復(fù)生氣的跡

5、象,藉由大量的改良了木材的加工方法,各種不同的處理方法增加了木材的耐久性, 而且疊片木材連同使用黏結(jié)技術(shù)的革命使得木材的性能有了更好的保證。各向同性的膠合板是最廣泛使用的壓層膠合板，隨著技術(shù)的發(fā)展，壓層膠合板已經(jīng)發(fā)展成為特定的結(jié)構(gòu)材料并對混凝土和鋼造成了強大的競爭力。將來可能發(fā)展的材料是工程塑料和稀有金屬及他們的合金,如鈹，鎢，鉭，鈦，鉬，鉻，釩和鈮。有許多不同的塑料可以用，而且這些材料所展現(xiàn)的力學(xué)性能在很大的范圍內(nèi)改變。在如此許多的特性中我比較設(shè)計方案選擇適當(dāng)?shù)目赡艿乃芰喜牧鲜强赡艿?。對塑料的使用受?jīng)驗的限制。一般而言，塑料一定要與空氣隔離。設(shè)計的這一個方面要求主要是對塑料結(jié)構(gòu)元素在使用中的

6、考慮。 塑料被應(yīng)用的最有希望的潛能之一是嵌板和貝殼型結(jié)構(gòu)。疊片或夾心嵌板已經(jīng)被用于此種結(jié)構(gòu)以鼓勵未來建筑大量應(yīng)用這一個類型材料。另一種引起注意的材料由纖維或像粒子的膠結(jié)加筋的微粒組成的合成物材料正在開發(fā)。雖然一種由玻璃或塑料膠結(jié)材料組成的玻璃纖維加筋合成物已經(jīng)被用長達(dá)數(shù)年之久, 但是他們很可能退落為次要的結(jié)構(gòu)材料。加筋混凝土是另一個積極地被學(xué)習(xí)而且發(fā)展的混合料。一些實驗正在工作情況下進行。實驗主要內(nèi)容為鋼和玻璃纖維，但是大部份的使用經(jīng)驗在鋼纖維方面比較先進。Building materialsThe most serious disadvantage of steel is that it o

7、xidizes easily and must be protected by paint or some other suitable coating. When steel is used in an enclosure where a fire could occur, the steel members must be encased in a suitable fire-resistant enclosure such as masonry, concrete. Normally, steel members will not fail in a brittle manner unl

8、ess an unfortunate combination of metallurgical composition, low temperature, and bi-or triaxial stress exists.Structural aluminum is still not widely used in civil engineering structures, though its use is steadily increasing. By a proper selection of the aluminum alloy and its heat treatment, a wi

9、de variety of strength characteristics may be obtained. Some of the alloys exhibit stress-strain characteristics similar those of structural steel, except that the modulus of elasticity for the initial linearly elastic portion is about 10,000,000 psi (700,000 kgf/cm*cm) or about one-third that of st

10、eel. Lightness and resistance to oxidation are, of course, two of the major advantages of aluminum. Because its properties are very sensitive to its heat treatment, care must be used when riveting or welding aluminum. Several techniques have been developed for prefabricating aluminum subassemblies t

11、hat can be readily erected and bolted together in the field to form a number of beautiful and well-designed shell structures. This general procedure of prefabrication and held assembly by bolting seems to be the most promising way of utilizing structural aluminum.Reinforced and prestesses concrete s

12、hare with structural material. Natural cement concretes have been used for centuries. Modern concrete construction dates from the middle of the nineteenth century, though artificial Portland cement was patented by Aspidin, an Englishman, about 1825. Although several builders and engineers experiment

13、ed with the use of steel-reinforced concrete in the last half of the nineteenth century, its dominant use as a building material dates from the early decades of the twentieth century. The last fifty years have seen the rapid and vigorous development of prestressed concrete design and construction, f

14、ounded largely on early work by Freyssinet in France and Magnel in Belgium.Plain (unreinforced) concrete not only is a heterogeneous material but also has one very serious defect as a structural material, namely, its very limited tensile strength, which is only of the order of one-tenth its compress

15、ive strength. Not only is tensile failure in concrete of a brittle type, but likewise compression failure occurs in a relatively brittle fashion without being preceded by the forewarning of large deformations. (Of course, in reinforced-concrete construction, ductile behavior can be obtained by prope

16、r selection and arrangement of the reinforcement.) Unless proper care is used in the selection of aggregates and in the mixing and placing of concrete, frost action can cause serious damage to concrete masonry. Concrete creeps under long-term loading to a degree that must be considered carefully in

17、selecting the design stress conditions. During the curing process and its early life, concrete shrinks a significant amount, which to a degree can be controlled by properly proportioning the mix and utilizing suitable construction techniques.With all these potentially serious disadvantages, engineer

18、s have learned to design and build beautiful, durable, and economical reinforced-concrete structures for practically all kinds of structural requirements. This has been accomplished by careful selection of the design dimensions and the arrangement of the steel reinforcement, development of proper ce

19、ments, selection of proper aggregates and mix proportions, careful control of mixing, placing, and curing techniques and imaginative development of construction methods, equipment and procedures.The versatility of concrete, the wide availability of its component materials, the unique ease of shaping

20、 its form to meet strength and functional requirements, together with the exciting potential of further improvements and development of not only the newer prestressed and precast concrete construction but also the conventional reinforced concrete construction, combine to make concrete a strong compe

21、titor of other materials in a very large fraction of structures.In modern times, with the increased use of steel and reinforced-concrete construction, wood has been relegated largely to accessory use during construction, to use in temporary and secondary structures, and to use for secondary members

22、of permanent construction. Modern technology in the last sixty years has revitalized wood as a structural material, however, by developing vastly improved timber connectors, various treatments to increase the durability of wood, and laminated wood made of thin layers bonded together with synthetic g

23、lues using revolutionary gluing techniques. Plywood with essentially nondirectional strength properties is the most widely used laminated wood, but techniques have also been developed for building large laminated wood members that for certain structures are competitive with concrete and steel.Materi

24、als with future possibilities are the engineering plastics and the exotic metals and their alloys, such as beryllium, tungsten, tantalum, titanium, molybdenum, chromium, vanadium, and niobium. There are many different plastics available, and the mechanical properties exhibited by this group of mater

25、ials vary over a wide range that encompasses the range of properties available among the more commonly used structural materials. Thus in many specific design applications it is possible to select a suitable plastic material for an alternative design. Experience with the use of plastics outdoors is limited. Generally speaking, however, plastics must be protected from the weather. This aspect of design is therefore a major consideration in the use of plastics for primary structural elements. One of the most promising potential used of