土木专业外语PPT课件

1、1Words 1. elasticity 弹性，弹力 elastic adj. 弹性的 2. stiffness n. 刚度，硬度 stiff adj. 硬的, 僵直的, 拘谨的, 呆板的, 艰难的, 费劲的, 僵硬的 如：stiff frame 刚架， stiff girder 加劲梁 stiffen vt. 使硬, 使僵硬, 使生硬, 使粘稠 vi. 变粘, 变硬, 变猛烈 21. thermosetting 热凝性的，热固性的 thermo- 表示“热、热电”之义 如：thermoanalysis 热(学)分析 thermoalloy 热磁合金第1页/共70页2Building Mate

2、rials Materials for building must have certain physical properties to be structurally useful 建筑材料必须具有某些对结构有用的物理性能。 Primarily，they must be able to carry a load, or weight, without changing shape permanently 首先，它们必须能在不永久变形的情况下承受荷载或重量。 When a load is applied to a structure member，it will deform；that is

3、, a wire will stretch or a beam will bend 当荷载被施加到结构构件上时，构件将产生变形，即，钢丝将拉伸而梁将弯曲。 However，when the load is removed, the wire and the beam come back to the original positions 然而，当荷载移除时，钢丝和梁都将恢复原来的状态。 This material property is called elasticity. 这种特性就被称为弹性。第2页/共70页3 If a material were not elastic and a de

4、formation were present in the structure after removal of the load, repeated loading and unloading eventually would increase the deformation to the point where the structure would become useless. 如果材料不是弹性的，结构中的变形在荷载移除后仍然存如果材料不是弹性的，结构中的变形在荷载移除后仍然存在，那么重复加载和卸载将最终使变形增加到结构不能使用的在，那么重复加载和卸载将最终使变形增加到结构不能使用的程

5、度。程度。 All materials used in architectural structures，such as stone and brick, wood, steel, aluminum, reinforced concrete，and plastics，behave elastically within a certain defined range of loading. 在建筑结构中使用的所有材料，如石头和砖、木材、钢材、在建筑结构中使用的所有材料，如石头和砖、木材、钢材、铝材、钢筋混凝土和塑料等，在某个有限的荷载范围内均表现铝材、钢筋混凝土和塑料等，在某个有限的荷载范围内均

6、表现出弹性。出弹性。 If the loading is increased above the range，two types of behavior can occur：brittle and plastic. In the former, the material will break suddenly 如果荷载增加到超过了这个范围，那么可能表现出两种特如果荷载增加到超过了这个范围，那么可能表现出两种特性：脆性和塑性。在前者中，材料将突然破裂。性：脆性和塑性。在前者中，材料将突然破裂。Building Materials 第3页/共70页4Building Materials In th

7、e latter，the material begins to flow at a certain load(yield strength), ultimately leading to fractureAs examples，steel exhibits plastic behavior, and stone is brittle. 在后者中，材料在某个荷载（屈服强度）下开始塑性变形，最终导致断裂。例如，钢表现出塑性，石头则是脆性。 The ultimate strength of a material is measured by the stress at which failure(f

8、racture) occurs 材料的极限强度通过发生破坏（断裂）时的应力来测量。 A second important property of a building material is its stiffness 建筑材料的第二个重要特性是它的刚度。 This property is defined by the elastic modulus, which is the ratio of the stress(force per unit area)，to the strain(deformation per unit length). 这种特性由弹性模量来定义，弹性模量是应力（单位面

9、积的力）与应变（单位长度的变形）的比值。第4页/共70页5 The elastic modulus，therefore，is a measure of the resistance of a material to deformation under load. 因此，弹性模量是材料抵抗荷载作用下变形能力的度量单位。 For two materials of equal area under the same load，the one with the higher elastic modulus has the smaller deformation. 在相同荷载下，相同面积的两种材料，高弹

10、性模量的一种具有较小的变形。 Structural steel, which has an elastic modulus of 30 million pounds per square inch (psi), or 2,100,000 kilograms per square centimeter，is 3 times as stiff as aluminum，10 times as stiff as concrete，and 15 times as stiff as wood 型钢，有30000000磅每平方英尺的弹性模量，其刚度是铝的3倍，混凝土的10倍，木材的15倍。Building

11、Materials 第5页/共70页6 Masonry consists of natural materials，such as stone，or manufactured products，such as brick and concrete blocks. 圬工包括天然材料，如石头，或者制成品，如砖和混凝土块。 Masonry has been used since ancient times；mud bricks were used in the city of Babylon for secular buildings，and stone was used for the great

12、 temples of the Nile Valley 圬工从古代就开始被使用了；泥砖被用在巴比伦城市的非宗教建筑物中，石头被用在尼罗河流域的大寺庙中。 The Great Pyramid in Egypt, standing 481 feet(147 meters)high，is the most spectacular masonry construction 埃及的大金字塔，高147m，是最壮观的圬工建筑。 Masonry units originally were stacked without using any bonding agent，but all modern masonr

13、y construction uses a cement mortar as a bonding material 圬工单元最初是没有使用任何粘结剂而堆积在一起的，但是所有的现代圬工建筑都使用了水泥砂浆作为粘合材料。 Masonry第6页/共70页7 Modern structural materials include stone，bricks of burnt clay or slate，and concrete blocks 现代建筑材料包括石头，烧结粘土砖或板岩，以及混凝土砌块。 Masonry is essentially a compressive material；it cann

14、ot withstand a tensile force，that is，a pull 圬工实质上是一种抗压材料；它不能承担拉力。 The ultimate compressive strength of bonded masonry depends on the strength of the masonry unit and the mortar 砌合的圬工材料的极限抗压强度取决于圬工单元和砂浆的强度。 The ultimate strength will vary from 1,000 to 4,000 psi(70 to 280 kgsq cm)，depending on the pa

15、rticular combination of masonry unit and mortar used 极限强度将在1000到4000psi之间变化，这取决于圬工单元和所使用的砂浆的特定组合。 Masonry第7页/共70页8 Timber is one of the earliest construction materials and one of the few natural materials with good tensile properties. 木材是最早的建筑材料之一，是为数不多的具有好的抗拉特性的天然材料之一。 Hundreds of different species

16、 of wood are found throughout the world，and each species exhibits different physical characteristics 世界各地可以发现成百上千个不同品种的木材，每一个品种都表现出不同的物理特征。 Only a few species are used structurally as framing members in building construction. 只有少数的种类在建筑施工中作为框架构件在结构中使用。 In the United States，for instance，out of more t

17、han 600 species of wood, only 20 species are used structurally 比如，在美国，在超过600个木材品种中，只有20种在结构中使用。 Timber第8页/共70页9 These are generally the conifers，or softwoods，both because of their abundance and because of the ease with which their wood can be shaped 这些通常是针叶松，或软木，是因为它们产量丰富并容易成型。 The species of timber

18、 more commonly used in the United States for construction are Douglas fir，Southern pine，spruce，and redwood. 在美国更通常被用于建筑的木材品种是美国松，南方松，云杉和红木。 The ultimate tensile strength of these species varies from 5,000 to 8,000 psi(350 to 560 kgsq cm). 这些品种的极限抗拉强度从5000变化到8000psi。 Hardwoods are used primarily for

19、cabinetwork and for interior finishes such as floors 硬木最初是被用作细木家具和内部的成品，比如地板。 Because of the cellular nature of wood，it is stronger along the grain than across the grain 因为木材多孔的特征，它沿纹理方向的强度比跨纹理方向的强度要大。 Timber第9页/共70页10 Wood is particularly strong in tension and compression parallel to the grain，and

20、it has great bending strength 木材在平行于纹理方向的抗拉和抗压能力都特别强，它还有很大的抗弯强度。 These properties make it ideally suited for columns and beams in structures 这些特性使它在结构中非常理想地适用于梁和柱。 Wood is not effectively used as a tensile member in a truss, however, because the tensile strength of a truss member depends upon connec

21、tions between members 然而，木材却不能被有效地用作桁架中的抗拉构件，因为桁架构件的抗拉强度取决于构件之间的连接。 It is difficult to devise connections which do not depend on the shear or tearing strength along the grain, although numerous metal connectors have been produced to utilize the tensile strength of timbers 虽然生产了许多利用木材抗拉强度的金属连接器，但是很难设

22、计与沿木材顺纹方向抗剪强度或抗扯裂强度关系不大的接头。 Timber第10页/共70页11 Steel is an outstanding structural material 钢筋是一种重要的结构材料。 It has a high strength on a pound-for-pound basis when compared to other materials, even though its volume-for-volume weight is more than ten times that of wood. 当和其他材料比较时，相同重量的基础上它有更高的强度，即使相同体积的重

23、量是木材的十倍。 It has a high elastic modulus，which results in small deformations under load 它有较高的弹性模量，其结果就是荷载作用下变形较小。 It can be formed by rolling into various structural shapes such as I-beams，plates，and sheets； it also can be cast into complex shapes；and it is also produced in the form of wire strands an

24、d ropes for use as cables in suspension bridges and suspended roofs，as elevator ropes，and as wires for prestressing concrete 它能通过碾压被做成不同的结构型式，比如I梁，板和薄板；它还可以被浇铸成复杂的型式；它还可以被制成用作悬索桥和悬吊式屋顶中缆索的钢丝绳和钢丝索的形状，用作电梯吊索，和预应力混凝土的钢丝索。 Steel第11页/共70页12 Steel elements can be joined together by various means，such as b

25、olting，riveting，or welding 钢筋构件能通过不同的方式连接在一起，比如螺栓连接，铆接，或焊接。 Carbon steels are subject to corrosion through oxidation and must be protected from contact with the atmosphere by painting them or embedding them in concrete. 碳素钢在氧化作用下会腐蚀，必须要通过喷漆或把它们嵌入混凝土中从而避免与空气接触来加以保护。 Above temperatures of about 700 F(

26、371)，steel rapidly loses its strength, and therefore it must be covered in a jacket of a fireproof material(usually concrete)to increase its fire resistance 当温度高于371时，钢筋很快就会损失掉它的强度，因此必须要用一种防火材料（通常是混凝土）将它包裹起来以增加它的抗火性。 Steel第12页/共70页13 The addition of alloying elements，such as silicon or manganese，res

27、ults in higher strength steels with tensile strengths up to 250,000 psi(17,500 kgsq cm) 加入合金元素，如硅或锰，将得到抗拉强度高达250000psi的高强度的钢筋。 These steels are used where the size of a structural member becomes critical，as in the case of columns in a skyscraper 这些钢筋被用在结构构件的尺寸很重要的结构中，比如摩天大楼的柱子中。 Steel第13页/共70页14 Alu

28、minum is especially useful as a building material when lightweight，strength，and corrosion resistance are all important factors 当轻质、强度和抗腐蚀成为所有的重要因素时，铝就是一种特别有用的建筑材料。 Because pure aluminum is extremely soft and ductile, alloying elements, such as magnesium，silicon，zinc，and copper，must be added to it to

29、 impart the strength required for structural use 因为纯铝非常软且具韧性，所以必须要添加一些合金元素，如锰、硅、锌和铜等，以给它提供结构使用所需要的强度。 Structural aluminum alloys behave elastically 结构铝合金表现出弹性。 They have an elastic modulus one third as great as steel and therefore deform three times as much as steel under the same load 它们的弹性模量是钢筋的1/

30、3，因此在相同的荷载条件下其变形就是钢筋的3倍。 Aluminum 第14页/共70页15 The ultimate tensile strength of aluminum alloys ranges from 20,000 to 60,000 psi(1,400 to 4,200 kgsq cm) 铝合金的极限抗拉强度变化范围在20000到60000psi之间。 Aluminum can be formed into a variety of shapes；it can be extruded to form I-beams，drawn to form wire and rods, and

31、 rolled to form foil and plates. 铝能被塑造成不同的型式；它能被压制成I梁，拉伸成丝和棒，碾压成薄片和板。 Aluminum members can be put together in the same way as steel by riveting, bolting，and(to a lesser extent)by welding 铝构件能用和钢筋一样的方式，铆接、螺栓连接和焊接等连接到一起。 Apart from its use for framing members in buildings and prefabricated housing，alu

32、minum also finds extensive use for window frames and for the skin of the building in curtain-wall construction 除了用于建筑物和预制装配式房屋中的框架构件以外，铝还有更广泛的用途用于窗框和幕墙建筑结构的外表面。 Aluminum 第15页/共70页16 Concrete is a mixture of water，sand and gravel，and portland cement 混凝土是水、砂和砾石、以及波特兰水泥的混合物。 Crushed stone, manufactured

33、 lightweight stone, and seashells are often used in lieu of natural gravel 碎石、人造轻型石料和贝壳通常被用在自然砾石的场所。 Portland cement, which is a mixture of materials containing calcium and clay，is heated in a kiln and then pulverized 波特兰水泥，它是钙和粘土的混和材料，在窑里加热然后研成粉末。 Concrete derives its strength from the fact that pu

34、lverized portland cement，when mixed with water, hardens by a process called hydration 混凝土的强度来自于：粉碎的波特兰水泥，当和水混和的时候，就通过一个被称为水合作用的过程硬化。 In an ideal mixture，concrete consists of about three fourths sand and gravel(aggregate)by volume and one fourth cement paste 在理想的混合物中，混凝土由大约3/4体积的砂和砾石（骨料）及1/4的水泥浆组成。 C

35、oncrete 第16页/共70页17 The physical properties of concrete are highly sensitive to variations in the mixture of the components，so a particular combination of these ingredients must be custom-designed to achieve specified results in terms of strength or shrinkage 因为混凝土的物理特性对成分组合的变化十分敏感，所以这些成分的一个特定的组合就必须

36、根据强度或收缩来习惯性地设计得到达特定的结果。 When concrete is poured into a mold or form，it contains free water，not required for hydration, which evaporates 当混凝土被注入进一个模型时，它含有游离水，不需要水合作用，这些水会蒸发。 As the concrete hardens，it releases this excess water over a period of time and shrinks 当混凝土硬化时，它会在一段时间释放出多余的水并收缩。 As a result

37、of this shrinkage，fine cracks often develop 收缩的结果往往是产生细微的裂缝。 Concrete 第17页/共70页18 In order to minimize these shrinkage cracks，concrete must be hardened by keeping it moist for at least 5 days 为了使这些收缩裂缝减到最少，必须使混凝土在保持至少5天的潮湿状态下硬化。 The strength of concrete increases in time because the hydration proces

38、s continues for years；as a practical matter，the strength at 28 days is considered standard 混凝土的强度随着时间的增加而增强，因为水合作用会持续很多年；作为一种工程材料，28天强度被考虑作为标准。 Concrete deforms under load in an elastic manner 混凝土在荷载下的变形是弹性模式。 Although its elastic modulus is one tenth that of steel，similar deformations will result s

39、ince its strength is also about one tenth that of steel 虽然其弹性模量是钢筋的1/10，但是将产生相近的变形，因为其强度也大约是钢筋的1/10。 Concrete is basically a compressive material and has negligible tensile strength 混凝土基本上是一种抗压材料，抗拉强度是微不足道的。 Concrete 第18页/共70页19 Reinforced concrete has steel bars that are placed in a concrete member

40、 to carry tensile forces 钢筋混凝土有放置在混凝土构件中用来承担拉力的钢条。 These reinforcing bars，which range in diameter from 0.25 inch(0.64 cm)to 2.25 inches (5.7 cm)，have wrinkles on the surfaces to ensure a bond with the concrete 这些钢筋，直径范围从0.25英寸到2.25英寸，表面有纹路以保证和混凝土的粘结。 Although reinforced concrete was developed in man

41、y countries，its discovery usually is attributed to Joseph Monnier，a French gardener，who used a wire network to reinforce concrete tubes in 1868 虽然钢筋混凝土在许多国家被生产，但是它的发现通常被归功于Joseph，一个法国的花匠，他曾在1868年使用钢筋网加固混凝土管。 This process is workable because steel and concrete expand and contract equally when the tem

42、perature changes 这种做法切实可行是因为钢筋和混凝土在温度变化时其膨胀和收缩相等。 Reinforced Concrete 第19页/共70页20 If this were not the case，the bond between the steel and concrete would be broken by a change in temperature since the two materials would respond differently 如果情况不是这样，那么钢筋和混凝土间的粘结将在温度变化时受到破坏，因为这两种材料的反应不同。 Reinforced c

43、oncrete can be molded into innumerable shapes，such as beams，columns，slabs，and arches，and is therefore easily adapted to a particular form of building 钢筋混凝土可被浇铸成各种形状，例如梁、柱、板和拱，因此它易适用于建筑的特殊结构。 Reinforced concrete with ultimate tensile strengths in excess of 10,000 psi(700 kgsq cm)is possible，although

44、most commercial concrete is produced with strengths under 6,000 psi(420 kgsq cm) 极限抗拉强度超过10000psi的钢筋混凝土都是有可能的，虽然大多数生产出来的商业混凝土的强度都低于6000psi。 Reinforced Concrete 第20页/共70页21 Plastics are rapidly becoming important construction materials because of the great variety，strength，durability，and lightness 塑料

45、因为它的多样化，强度，耐久性，和轻质性，很快就成为了重要的建筑材料。 A plastic is a synthetic material or resin which can be molded into any desired shape and which uses an organic substance as a binder 塑料是一种合成材料或树脂，它能被浇铸成任何期望的形状，它还使用有机物质作为粘结剂。 Organic plastics are divided into two general groups：thermosetting and thermoplastic 有机塑料

46、被分为了两个大的类别：热凝性和热塑性。 Plastics 第21页/共70页22 The thermosetting group becomes rigid through a chemical change that occurs when heat is applied；once set，these plastics cannot be remolded 当加热时，热凝性一类就会发生化学变化变硬；一旦凝固，这些塑料就不能够再重铸。 The thermoplastic group remains soft at high temperatures and must be cooled bef

47、ore becoming rigid，this group is not used generally as a structural material 热塑性这一类在高温下仍保持柔软，而且在变硬以前必须要降温；这一类通常不能作为结构材料使用。 The ultimate strength of most plastic materials is from 7,000 to 12,000 psi(490 to 840 kgsq cm)，although nylon has a tensile strength up to 60,000 psi(4.200 kgsq cm) 大部分塑料的极限强度在

48、7000到12000psi之间，虽然尼龙的抗拉强度高达60000psi。 Plastics 第22页/共70页23 This text introduced some knowledge about building materials. Primarily, building materials must have elasticity. A second important property of a building material is its stiffnessThe text introduced detailedly the following building materia

49、ls which are used frequently: masonry, timber, steel, aluminum, concrete, reinforced concrete and plastic. 这篇文章介绍了建筑材料的一些知识。首先，建筑材料必这篇文章介绍了建筑材料的一些知识。首先，建筑材料必须具有弹性。建筑材料的第二个重要特性是它的刚度。文章详须具有弹性。建筑材料的第二个重要特性是它的刚度。文章详细地介绍了一下几种常用的建筑材料：砖石材料、木材、钢材、细地介绍了一下几种常用的建筑材料：砖石材料、木材、钢材、铝、混凝土、钢筋混凝土和塑料。铝、混凝土、钢筋混凝土和塑料。 要求

50、：掌握本课的专业词汇和专业知识以及一些翻译技巧。要求：掌握本课的专业词汇和专业知识以及一些翻译技巧。Brief Summary第23页/共70页24Lesson 19 Structural Analysis结构分析New words and phrases:ascertain procedure facilitate abrupt complexity coplanar nonconcurrent reaction superposition unknown contraflexure laborious redundant simultaneous algebra multiplicatio

51、n invert random neutral axis 中和轴timeconsuming 耗时的pin joint 铰接angular displacement 角位移earthquakeresistant 抗地震的statically indeterminate structure 超静定结构第24页/共70页25Structural Analysis All structures must be designed to support loads without danger of overall collapse or failure of the components 所有的结构都必

52、须被设计得在不出现全面的倒塌或构件的破坏等危险的条件下就能支撑荷载。 One way to assure structure safety is to ascertain that stresses and strains produced by loads are less than those allowed by established design codes 保证结构安全的一种方法是确定由荷载产生的应力、应变比公认的设计规范所容许的应力、应变小。 This determination of stresses and strains in structures is a primary

53、 objective of structural analysis. 在结构中确定应力和应变是结构分析的主要的目的。 Generally，analysis begins with a check of the overall stability of a structure 通常，分析是从检查结构的总体稳定性开始的。第25页/共70页26 This involves the determination of the forces exerted by the structure against its supports. 这涉及到确定结构施加到它的支撑的力。这涉及到确定结构施加到它的支撑的力。

54、 If the supports are adequate to withstand the forces，they in turn react with equal but opposite forces against the structure. 如果支撑足够承受这些力，那么它们依次作用大小相等的反如果支撑足够承受这些力，那么它们依次作用大小相等的反力到结构上。力到结构上。 If computation shows that the reactions balance the loads (weight of structure, occupants, stored materials，

55、vehicles，wind，and earthquake forces)，the structure is in static equilibrium. 如果计算显示反力平衡了荷载（结构、人群、存放的材料等如果计算显示反力平衡了荷载（结构、人群、存放的材料等的重量，车辆荷载，风力和地震力），那么结构就处于静力平衡的重量，车辆荷载，风力和地震力），那么结构就处于静力平衡状态。状态。 The next step is determination of internal forces and unit stresses in the components of the structure. 接下来的

56、一步就是确定结构的各组成部分的内力和单位应力。接下来的一步就是确定结构的各组成部分的内力和单位应力。Structural Analysis第26页/共70页27Structural Analysis Finally，if necessary，the deformation of the structure as a whole and of its components may be calculated. 最后，如果需要的话，还可能计算结构整体和各部分的变形。 These steps are facilitated by use of principles and concepts such

57、 as the law of equilibrium. 通过使用一些原理和概念，比如平衡原理，可以简化这些步骤。 Many of these tools are based on the assumption that the structure is elastic under loads；that is, stress is proportional to strain 这些工具中的许多都是基于这样一个假定：结构在荷载作用下是弹性的，也就是说，应力和应变成比例。 The structural analysis for stresses and strains in frame member

58、s includes consideration of static loads，such as the weight of the members and floors，contents of the building，and live loads (considered to be static)，and dynamic loads such as wind and earthquakes 框架构件中，应力和应变的结构分析包括静荷载的考虑，比如构件和楼板的重量，建筑物容量的考虑，活荷载的考虑（被认为是静态的），动荷载比如风和地震荷载的考虑。第27页/共70页28 Because of th

59、e nature of wind and the lack of better information，wind forces are considered to be statically applied to the structure 因为风的特性和缺乏更好的信息，所以风力往往被考虑成静止地施加到结构上。 The manner of calculating the loads and location of lines of action on the building face are prescribed by local building codes 计算荷载的模式和作用到建筑物表

60、面的（荷载）路线的位置由当地的建筑规范规定。 On the other hand，earthquake motions are applied at the base of the building from the ground below and are considered to be a random-type loading 另一方面，地震运动从地下施加到建筑物的基础上，被考虑成随机荷载。 The analysis for gravity and wind loads is performed by the application of the usual methods for l