7 Structural Steel 结构钢.ppt

Structural Steel钢结构 教学目标 了解钢材作为结构材料的优缺点 了解不同性能的结构钢的应力-应变关系 熟悉各种描述结构钢性能、特点的词汇 熟悉科技类文献的常用句型 A person traveling in the United States might quite understandably decide（清楚地断定）that steel was the perfect structural material. He or she would see an endless number of（无穷无尽的）steel bridges, buildings, towers, and other structures comprising, in fact, a list too lengthy to enumerate（列举）. After seeing these numerous steel structures this traveler might be quite surprised to learn（了解）that steel was not economically made in the United States until late in the nineteenth century and the first wide-flange beams were not rolled（轧制）until 1908. The assumption of the perfection（完美）of this metal, perhaps the most versatile（通用的）of structural materials, would appear to be even more reasonable（合理的）when its great strength, light weight, ease of fabrication（制作）, and many other desirable（理想的） properties are considered（考虑）. These and other advantages of structural steel are discussed in detail（详细地）in the following paragraphs. 　　　当考虑这种金属具有高强、轻质、易制作以及很多其它理想的性能时，认为其完美的假定甚至显得更合理，或许它是最通用的建筑材料。这些和其它的结构钢的优势将在下面的段落中详细地讨论。 High Strength　　The high strength of steel per unit of weight means that structure weights will be small. This fact is of great importance for long-span bridges, tall buildings, and structures having poor foundation conditions（薄弱地基条件）. 高强度　　钢材每单位重量的高强度意味着结构的重量将是小的。这个事实对大跨的桥梁、高层建筑以及有着薄弱地基条件的结构具有重要意义。 Uniformity　　The properties of steel do not change appreciably（明显地）with time, as do those of reinforced-concrete structure. 一致性　　钢材的性能随时间的变化不明显，而钢筋混凝土结构的性能则随时间变化。 Elasticity　　Steel behaves closer to（更接近于）design assumptions than most materials because it follows（遵循）Hooke’s law up to fairly high stresses. The moments of inertia（惯性矩）of a steel structure can be definitely（确切地） calculated, while the value obtained for a reinforced-concrete structure are rather indefinite（不确切）. 弹性　　比起大多数材料，钢材的运行更接近于设计的假定，因为它直到相当高的应力仍然遵循虎克定理。一个钢结构的惯性矩可以确切地被计算，而钢筋混凝土结构得到的该值是非常得不确切。