第2单元(第6).ppt

1、1,Modern Buildings and Structural Materials,现代建筑与结构材料,2,【Objectives（教学目标）】：本课主要介绍现代建筑和建筑材料方面的基本知识，同时也介绍了建筑结构受力方面的特点，并应根据此特点来使用相关的建筑材料，通过本课的学习，应掌握建筑材料的基本特点及其适用范围，掌握相关的专业词汇。,【Key Issues（教学重点）】：建筑结构的受力特点，建筑材料的特性及其适用性。,3,Many great buildings built in earlier ages are still in existence and in use. Among

2、 them are the Pantheon and the Colosseum in Rome, Hagia Sophia in Istanbul; the gothic churches of France and England, and the renaissance cathedrals, with their great domes, like the Duomo in Florence and ST.Peters in Rome.,许多古代修建的大型建筑物现仍存在着，而且仍在使用。其中有罗马的万神庙（潘提翁神庙）和大斗兽场，伊斯坦布尔的圣索非亚教堂，法国和英国的哥特式教堂，和带有

3、巨大的穹窿顶的文艺复兴式教堂，象佛罗伦萨的大教堂和罗马的圣彼得大教堂。,Paragraph 1,Gothic churches ：哥特式教堂 Renaissance：文艺复兴 Dome：圆屋顶 Cathedral：大教堂,4,They are massive structures with thick stone walls that counteract the thrust of their great weight. Thrust is the pressure exerted by each part of a structure on its other parts.,它们都是些厚石

4、墙的庞大建筑。这种厚石墙能抵抗建筑物本身巨大重量所形成的推力。 推力是建筑物各部分作用于其它部分的压力。,Paragraph 1,Massive ：厚重的, 大块的, 魁伟的, 结实的 Counteract ：抵消, 中和, 阻碍 Thrust：推力, 猛推, 插, 戳, 刺,5,罗马万神庙,6,罗马万神庙（续）,7,罗马万神庙（续）,8,罗马大角斗场,9,罗马大角斗场（续）,10,罗马大角斗场（续）,11,圣索非亚教堂,12,圣索非亚教堂（续）,13,圣索非亚教堂（续）,14,圣彼得大教堂,15,圣彼得大教堂（续）,16,圣彼得大教堂（续）,17,These great buildings

5、were not the product of knowledge of mathematics and physics. They were constructed instead on the basis of experience and observation, often as the result of trial and error.,这些大型建筑物并非数学和物理知识的结晶。它们都是依据经验和观察而建造起来的，往往是反复试验出来的结果。,Paragraph 2,Trial and error:反复试验,18,One of the reasons they have survive

6、d is because of the great strength that was built into them-strength greater than necessary in most cases. But the engineers of earlier times also had their failure.,它们能留存下来的原因之一是因为它们建造得强度很大多数情况下超出所需要的强度。可是古代的工程师也失败过。,Paragraph 2,Survive ：幸免于, 幸存, 生还,19,In Rome, for example, most of the people lived

7、 in insula, great tenement blocks that were often ten stories high. Many of them were poorly constructed and sometimes collapsed with considerable loss of life.,例如在罗马，大部分人民都住在公寓中，这种公寓通常是一排排的有十层高的公寓大楼。其中有许多建造得很差，并且有时会倒塌，使许多人丧生。,Paragraph 2,Insula ：群屋 Tenement ：房屋, 住户, 租房子 Block：木块, 石块, 块, 街区, 阻滞, 一批,

8、20,21,Today, however, the engineer has the advantage not only of empirical information, but also of scientific data that permit him to make careful calculations in advance.,但是，现在的工程师具备许多有利条件，不仅有经验资料，而且有供他预先做详细计算的科学数据。,Paragraph 3,Empirical ：完全根据经验的, 经验主义的,22,When a modern engineer plans a structure,

9、 he takes into account the total weight of all its component materials. This is known as the dead load, which is the weight of the structure itself.,一个现代工程师当他设计一座建筑物时，他要考虑这座建筑物所有组成材料的总重量，这就是所谓的静荷载，即建筑物自身的重量。,Paragraph 3,Dead load ：静荷载，恒载,23,He must also consider the live load, the weight of all the

10、people, cars, furniture, machines, and so on that the structure will support when it is in use.,他还必须考虑动荷载，即在建筑物使用时它要承受的人，车辆，设备、机器等等的重量。,Paragraph 3,Live load ：动荷载，活荷载 Furniture ：家具, 设备, 储藏物,24,In structures such as bridges that will handle fast automobile traffic, he must consider the impact, the fo

11、rce at which the live load will be exerted on the structure.,对于象桥梁这种需要承担高速汽车交通的构筑物，他必须考虑到冲力，即动荷载将借以作用于结构物的那种力。,Paragraph 3,Impact ：碰撞, 冲击, 冲突, 影响, 效果,25,He must also determine the safety factor, that is, an additional capability to make the structure stronger than the combination of the three other

12、factors.,他还必须确定出安全系数，即附加的承载能力，以使建筑物的承载能力比上述三个因素结合起来还要强些,Paragraph 3,26,The modern engineer must also understand the different stresses to which the materials in a structure are subject. These include the opposite forces of compression and tension. In compression the material is pressed or pushed tog

13、ether; in tension the material is pulled apart or stretched, like a rubber band.,现代工程师还必须了解建筑物材料要承受的各种应力，其中包括压力和拉力这两种相反的力。在受压下，材料被压紧或推拢到一起，在受拉下，材料象一个橡皮筋那样被拉开或拉长。,Paragraph 4,Compression ：压力 Tension：拉力 Rubber band： 橡皮筋,27,In addition to tension and compression, another force is at work, namely shear,

14、 which we defined as the tendency of a material to fracture along the lines of stress.,除了拉力和压力之外，还有一种称为剪力的力在起作用，我们给它下定义为，使材料沿应力线破坏的趋势,Paragraph 4,Shear ：剪力 Fracture：破裂, 骨折,28,The shear might occur in a vertical plane, but it also might run along the horizontal axis of the beam, the neutral plane, wh

15、ere there is neither tension nor compression.,剪力可能发生在垂直面上，但它也可能沿着梁的水平轴线中性面作用，中性面上既没有拉力也没有压力。,Paragraph 4,Neutral plane：中性面,29,Altogether, three forces can act on a structure: vertical-those that act up or down; horizontal-those that act sideways; and those that act upon it with a rotating or turning

16、 motion.,总的说来，有三种力作用于建筑物，垂直的那些向上或向下作用的力，水平的那些侧向作用的力，以及那些以一种旋转或转动的运动作用于建筑物上的力。,Paragraph 5,Vertical ：垂直的 Horizontal：水平的,30,Forces that act at an angle are a combination of horizontal and vertical forces. Since the structures designed by civil engineers are intended to be stationary or stable, these f

17、orces must be kept in balance.,成一个角度作用的力是水平力和垂直力的合力。因为土木工程师设计的建筑物总是力求使它们静止或稳定，因此这些力必须保持平衡。,Paragraph 5,Combination ：结合, 联合, 化合, 化合物 Stationary：固定的,31,The vertical forces, for example, must be equal to each other. If a beam supports a load above, the beam itself must have sufficient strength to count

18、erbalance that weight.,例如，各垂直力必须彼此相等。假如一个梁支承上面的一个荷载，梁本身必须有足够的强度去抗衡这个重量。,Paragraph 5,Counterbalance ：使平均, 使平衡, 弥补,32,The horizontal forces must also equal each other so that there is not too much thrust either to the right or to the left. And forces that might pull the structure around must be counte

19、red with forces that pull in the opposite direction.,水平力也必须彼此相等，才能不出现过多的向右或向左的推力。并且，那些可能推动构筑物转动的力必须由向反方向推动的力去抵销。,Paragraph 5,33,One of the most spectacular engineering failures of modern times, the collapse of the Tacoma narrows bridge in 1940, was the result of not considering the last of these fac

20、tors carefully enough.,现代最引人注目的工程事故之一1940年塔科马海峡大桥的倒塌，就是由于没有非常仔细地考虑这些因素中的最后一个因素。,Paragraph 6,Spectacular ：引人入胜的, 壮观的 Collapse：倒塌, 崩溃, 失败, 虚脱,34,When strong gusts of wind, up to sixty-five kilometers an hour, struck the bridge during a storm, they set up waves along the roadway of the bridge and also

21、a lateral motion that caused the roadway to fall.,在一场暴风雨中，当每小时高达65公里的强劲狂风冲击这座桥时，狂风引起了沿着桥面方向的波动；同时还产生了一种使路面塌落的横向运动。,Paragraph 6,Lateral ：横(向)的, 侧面的 Roadway：车行道, 路面, (铁道的)路线,35,1940年 11月7日上午11：0 刚开通几个月的塔科玛大桥（悬索桥）由于风致振动而倒塌！,1 中跨扭转,2 扭转的严重程度： 右侧人行道比左侧高8.5m,3 该开始破坏时， 有一块混凝土桥面掉入水中,4 第一轮破坏后的样子,5 中跨破坏后，边跨的松

22、弛、下垂现象,6 桥刚倒塌后的照片,36,Fortunately, engineers learn from mistakes, so it is now common practice to test scale models of bridges in wind tunnels for aerodynamic resistance.,Paragraph 6,Wind tunnels ： 风洞试验 Aerodynamic resistance ：空气动力学抵抗力,幸亏工程师们从错误中汲取了教训，所以现在的通常做法是将按比例缩小的桥梁模型放在风洞中检验它们的空气动力学抵抗力。,37,The p

23、rincipal construction materials of earlier times were wood and masonry brick, stone, or tile, and similar materials. The courses or layers were bound together with mortar or bitumen, a tar-like substance or some other binding agent.,早期的主要建筑材料是木材和砖，石、瓦，以及类似材料。 材料行或层之间，用灰浆或沥青(一种象焦油的物质)，或者别的粘结剂粘结在一起。,P

24、aragraph 7,Wood：木材 Masonry：圬工，砌筑 Tile：瓦 mortar：砂（灰）浆 Bitumen：沥青 Tar：焦油, 柏油 Binding agent：粘合剂，接合剂,38,The Greeks and Romans sometimes used iron rods or clamps to strengthen their buildings. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rust

25、ed away.,希腊人和罗马人有时还用铁条或铁夹子去加固建筑物。例如，雅典的帕提依神庙的圆柱上就有原来安装铁棍的钻孔，现在铁棍已经锈蚀掉了。,Paragraph 7,Iron rods：铁条 Clamp：夹子 Rust：铁锈,39,巴特农神庙,40,巴特农神庙（续）,41,巴特农神庙（续）,42,The Romans also used a natural cement called pozzolana, made from volcanic ash, that became as hard as stone under water.,罗马人还使用一种叫白榴火山灰的天然水泥，这是用火山灰制成

26、，在水中能变得和石头一样坚硬。,Paragraph 7,Pozzolana ：白榴 Volcanic ash ：火山灰,43,Both steel and cement, the two most important construction materials of modern times, were introduced in the nineteenth century. Steel ,basically an alloy of iron and a small amount of carbon, had been made up to that time by a laborious

27、 process that restricted it to such special uses as sword blades.,近代的两种最重要的建筑材料，钢材和水泥，都是十九世纪出现的。直到那时为止，钢(基本上是铁和少量碳的合金)一直是要经过很复杂的工艺过程才能制成的，这就使钢只限于用在制剑刃这类特殊的用途上,Paragraph 8,Alloy ：合金 Carbon ：碳 Laborious：艰苦的, 费力的, (指人)勤劳的 Sword blades：剑刃,44,cement,lime,45,46,steel wire,Steel bar,strand,47,48,国家体育场“鸟巢”是

28、2008年北京奥运会主体育场。 “鸟巢”是一个大跨度的曲线结构，以巨大的钢网围合、覆盖着9.1万人的体育场，采用了当今先进的建筑科技，其中，钢结构是世界上独一无二的。“鸟巢”钢结构总重4.2万吨，最大跨度343米，结构相当复杂，为国内外特有建筑。,49,After the invention of the Bessemer process in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile strength; that is,

29、 it does not lose its strength when it is under a calculated degree of tension, a force which, as we have seen, tends to pull apart many materials.,1856年发明贝色麦法以后，人们才能以低价大量地使用钢。钢的极大优点是它的抗拉强度，即：在特定程度拉力就象我们已经知道的那种会把许多种材料拉断的力的作用下，它的强度不会降低。,Paragraph 8,Bessemer process ：贝色麦法,50,New alloys have further in

30、creased 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.,新的合金进一步增强了钢的强度，并且还消除了它所存在的一些问题，如疲劳。疲劳是一种连续应力变化下材料强度的削弱。,Paragraph 8,Fatigue：疲劳,51,Modern cement, called Portland cement, was invented i

31、n 1824. It is a mixture of limestone and clay, which is heated and then ground into a powder. It is mixed at or near the construction site with sand, aggregate(small stones, crushed rock, or gravel), and water to make concrete.,Paragraph 9,Portland cement ：波特兰水泥Limestone ：石灰石 Clay ：粘土 Aggregate：骨料 C

32、rushed rock：碎石 Gravel：砾石,现代的波特兰水泥，是1824年发现的。是将石灰石和粘土的混合物加热后磨成粉末。在建筑现场或靠近现场的地方，将它与砂、骨料(小石子、碎石或砾石)、水混合后，就制成混凝土。,52,Different proportions of the ingredients produce concrete with different strength and weight. Concrete is very versatile; it can be poured, pumped, or even sprayed into all kinds shapes.,

33、不同的配料比例能制成不同强度和重量的混凝土。混凝土的适用性很强，它可以灌注，可以用泵抽送，甚至可喷射成各种各样的形状。,Paragraph 9,Ingredient：成分, 因素 Versatile：通用的, 多才多艺的, 多面手的 Pour：灌注, 倾泻, 涌入, 流, 倾盆大雨 Pump：(用泵)抽(水), 抽吸 Spray：喷射, 喷溅,53,54,And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances com

34、plement each other.,而且，钢有很大的抗拉强度，混凝土却有很大的抗压强度。因而，这两种材料可以互相补充。,Paragraph 9,Complement ：补助, 补足,55,They also complement each other in another way: they have almost the same rate of contraction and expansion. They therefore can work together in situations where both compression and tension are factors.,

35、它们还可以在其它方面互相补充：它们具有几乎相同的收缩率和膨胀率。因而它们可以在同时存在着压与拉力两种因素的情况下共同起作用。,Paragraph 10,Contraction：收缩, 缩写式, 紧缩 Expansion：扩充, 开展, 膨胀, 扩张物,56,Steel rods are embedded in concrete to make reinforced concrete in concrete beams or structures where tension will develop. Concrete and steel also form such a strong bond

36、-the force that unites them-that the steel cannot slip within the concrete.,在受拉的混凝土梁或结构中埋置钢筋，就制成钢筋混凝土。混凝土和钢还形成一种很强的粘结一种将它们连结起来的力使钢不能在混凝土中滑动。,Paragraph 10,Steel rods ：钢筋 Embed：使插入, 使嵌入 Reinforced concrete：钢筋混凝土 Bond：结合，粘结 Slip ：滑倒,57,Still another advantage is that steel does not rust in concrete. Ac

37、id corrodes steel, whereas concrete has an alkaline chemical reaction, the opposite of acid.,还有另一个优点就是钢在混凝土中不锈蚀。酸会腐蚀钢，而混凝土却具有与酸相反的碱性化学反应。,Paragraph 10,Acid ：酸, 酸的 Corrode：使腐蚀, 侵蚀 Alkaline：碱的, 碱性的,58,Prestressed concrete is an improved form of reinforcement. Steel rods are bent into the shapes to giv

38、e them the necessary degree of tensile strength. They are then used to prestress concrete, usually by pretensioning or posttensioning method.,预应力混凝土是钢筋混凝土的一种改进形式。钢筋被弯成各种形状以使它具有所需要的受拉强度。然后，通常采用先张法或后张法对混凝土预加应力。,Paragraph 11,Prestressed concrete :预应力混凝土Pretensioning :先张 Posttensioning：后张,59,Prestressed concrete has made it possible to develop buildings with unusual shapes, like some of the modern sports arenas, with large spaces unbroken by any obstructing supports. The uses for this relatively new structural method are constantly bei