第一单元

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 accomplish 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.

从根本上，工程是一个以最终产品为导向的行业，它具有创新、成本意识，同时也注意到人为因素。 它与创建新的实体、 设备或解决方案有关：新工艺、新材料、一个改进的动力来源、任务的一项更有效地安排，用以完成所需的目标或创建一个新的结构。 工程是也不仅仅关心获得经济的解决方案。最终，人类安全才是一个最重要的考虑因素。

Engineering is concerned with the use of abstract scientific ways of thinking and of defining real world problems. The use of idealizations and development of procedures for establishing bounds within which behavior can be ascertained are part of the process.

工程关心的是，使用抽象的科学方法思考和定义现实世界的问题。理想化的使用和发展建立可以确定行为的边界的程序，是过程的一部分。

Many problems, by their very nature, can’t be fully described—even after the fact, much less at the outset. Yet acceptable engineering solutions to these 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, processes, or solutions. And this, too, is all a part of engineering.

很多的问题，就其本身的性质而言，不能完全被描述 — — 即使这一事实，在其开始之前。然而还必须找到对于这些问题可接受的工程解决方案，来满足预定的需求。直觉或判断是建立可能的替代策略、 流程或解决方案的关键因素。。而这也是工程的一部分。

Because of the variety and kinds of input that must be taken into account at each and every stage in the solution process ,engineering problems are most often approached in what can be referred to as a hierarchically structured sequential decision process.certain things must be known ,and the influence of these ascertained before subsequent steps in the solution process can be approached.

在每一个阶段的求解过程中必须考虑由于不同类型的输入产生的影响工程问题通常以什么可被称为层级结构顺序决定process.必须知道某些东西,以及它们的影响在随后的步骤确定求解过程能够到达。

Emphasizing one of the concepts alluded to above,engineering is most often concerned with the development of permissible alternatives not necessarily the identification of a unique solution .true,aesthetics ,or other considerations may eventually dictate a particular ,singular choice from among several or even many possibilities ,but those acceptable ones will have been established prior to that final stage ,using normal engneering methods .

强调提到概念之一以上学历,工程是最经常关注发展选择允许不一定识别有唯一解.真理，美学、或其他的考虑可能最终决定某一特定,单一的选择在几个甚至更多的可能性,但是那些接受已经确立的之前最后一期工程中使用普通的方法。

Civil engineering is one of the most diverse branches of engineering. The civil engineer plans, designs, constructs, and maintains a large variety of structures and facilities for public, commercial and industrial use. These 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 sewage and waste disposal systems that add to our convenience and safeguard our health.

土木工程是工程的最多样化的分支机构之一。土木工程师计划、设计、施工，和维护大量的结构和公共、商业和工业使用的设施。这些结构包括住宅，办公室和工厂大厦；公路、铁路、机场、隧道、桥梁、港口、渠道和管道。在其他大多数的国家它们还包括运输系统许多其他设施，以及将为我们的生活带来便利的和维护我们的健康污水及废物处理系统。

The term “civil engineer” did not come into use until about 1750, when John Smeaton, the builder of famous Eddystone lighthouse near Plymouth, England, is said to have begun calling himself a “civil engineer” to distinguish himself from the military engineers of his time. However, the profession is as old as civilization.

直到大约1750年，人们才开始使用“土木工程师”这一术语。约翰.斯密顿在英格兰普利茅斯附近，建造了著名的埃迪斯通灯塔的建造师，开始自称为“土木工程师"来将自己与当时的军事工程师区分开。然而，土木工程这个职业却像文明一样古老。

In ancient Egypt the simplest mechanical principles and devices were used 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 used 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 used.

古埃及人用最简单的机械原理和装置建造了许多至今仍矗立的庙宇和金字塔，包括吉萨大金字塔和在卡纳克的Amon-Ra的寺庙。这个大金字塔，481英尺（146.6 米）高，由2250000个石块组成，石块的平均重量超过1.5吨（1.4 吨）。建造如此的纪念性建筑使用了大量的人力。埃及人也作了一些重达1000吨(900吨)的石头的大块切割的方尖塔。硬青铜的切削刀具在其中使用到了。

The Egyptians built causeways 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.

为了从采石场向尼罗河运输石材埃及人建造了长堤和道路。由埃及人竖设的大块石头通过使用拉杆、斜平面、滚子和雪橇来移动。

The Egyptians were primarily interested in the know-how of construction; They had very little interest in why-for of use .In contrast, the 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 base for Greek building construction included figures such as the square, rectangle, and triangle.

埃及人主要对如何建造感兴趣；他们对为什么这么使用没有什么太多的兴趣。相反，在公元前六世纪到公元前三世纪希腊人取得了巨大的进步于工程理论的推广。他们发展了线、角度、面，和实体的抽象的知识，而不是与特定的对象产生联系。 希腊建筑施工的几何基础包括数字如正方形、矩形和三角形。

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.

希腊建筑师 通常是建筑工程杰作的设计师同时也是建造师。 他既是一个建筑师也是工程师。工匠、石匠和雕塑家在他的监督下工作。在希腊古典时期所有重要建筑物是由石灰石或大理石建造的；以帕台农神庙为例，由大理石建成的。

Modern Civil Engineering

现代土木工程

和工程中其他分支一样，土木工程是这样一门学科，需要有通过学习得来的数学和自然科学的知识，经验和实践被合理的应用于开发新方法来经济的利用材料和自然的力量为人类所用。

目前的土木工程师的任务涉及空间的开发，热核能量的使用，弹道导弹设施的建造，以及空气和水污染的控制—这些材料和施工作业体系的发展在10年前是遥不可及的。早期以建造桥梁，公路，运河，高架渠，大坝，机场和水利分配系统为职业的土木工程师将一直被需要。更好的方法将会被开发来完成以前的任务，但是新的更复杂的困难将继续出现来挑战他。

分支 土木工程师的技术活动是各种各样的，与ASCE的专业划分是一致的，ASCE在美国是用来划分土木工程领域的。具体划分有输气，建造，工程机械，公路，水力学，灌溉和排水，管道，供能，结构，测绘，城区规划和发展，以及航路和海港。

这些专业划分的招募说明了ASCE的各组成主要是建筑方面的。所有专业划分的活动都包括建造，尽管不是他们主要的任务。建筑仍然是土木工程师主要的工作。

教育 美国土木工程学科学士学位通常需要高中毕业后四年的学习，尽管有些学校需要进行五年的课程学习。普遍认为需要更先进的专业和科学的训练，伴同更宽广的教育，包括一定的社会人文教育。土木工程四年的学士学位和四年适当的工程经验将会使一个年轻人有申请注册专业工程师的能力。

许可证 土木工程师在保护公众远离那些不称职的新手工程师方面发挥了重要的作用，1907年在美国怀俄明州，对第一个关于注册工程师州许可证条款的通过，土木工程师也扮演了领导性的角色，现在所有的州都有这样的法律；波多黎各，巴拿马运河地带，哥伦比亚地区同样有许可条款。在1920年，注册专业工程师的周立委员会建立了一个组织，叫全美州立工程验收委员会。在1967年，这个名字被简称为国家工程验收委员会。

第三单元

Both steel and cement，the two most important construction materials of modern times，were introduced in the mineteenth century.Steel,basically an alloy of iron and a small amount of carbon,had been made up to that time by a laborious process that restricted it to such special uses as sword blades.After the invention of the Bsssenmer process in1858,steel was available in large quantities at low prices.The enormous advantage of steel is its tensile strength;that is,it does mot lose its strength when it under a calculated degree of tension,a force which,as we have seen,tends to pull apart many materials.New alloys have further increased the strength of steel and eliminnated some of its problems,such as fatigue ,whech is a tendency for it to weaken as a result of continual changes in stress.

钢筋和水泥作为现代的两个最重要的结构材料，在19世纪时已经被引进。钢筋的主要成分是铁的合金和少量的碳。在那个时候它经历过了一个艰辛的过程后呗发明了，它被抵制做成像有特殊用途的刀剑。在1856年，贝塞尔法促进了以低廉的价格的钢的生产。钢主要的有利方面是它的抗拉强度。当它在确定拉力作用下，它不会失去强度，同时就像我们所看到的这个力将会拉开许多其它金属。新的合金已经更好地提高了钢的强度并消除了它的许多毛病，想在应力频繁改变作用下产生的疲劳而使它的强度变弱。

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.Steel rods are embedded in concrete to make reinforced concrete in concrete beans or structures where tension will develop.Concrete and steel also form such a strong bone---the force that unites them---that the steel cannot slip within the concrete.Still another advantage is that steel does not rust in concrete.Acid corrodes steel,whereas concrete has an alkaline chemical reaction,the opposite of acid.

由于它们的收缩和膨胀系数几乎相同，这也是它们相互补充不足的另一个方法。所以它们可以在同时有压力和拉力作用的情况下一起起作用。钢筋嵌入在混凝土中以提高混凝土梁或结构中的混凝土的强度，混凝土和钢筋也可以在力的作用下，使他们形成非常强的粘结，钢筋也不会在混凝土中发生滑动。另一个优点是钢筋不易在混凝土中生锈。酸腐蚀钢筋，然而跟酸相对的碱也会发生碱化学反应。

The adoption of structural steel and reinforced concrete caused major changes in traditional construcion practices.It was no longer necessary to use thick walls of stone or brick for multistory builidings,and it became much simpler to build fire-resistant floors.Both these changes served to reduce the cost of construction.It also became possible to erect buildings with greater heights ans longer spans.

钢结构和钢筋混凝土的采用在传统建筑方式中产生巨大的改变。不再需用沉重的用石头或砖做成的墙来建造高层建筑，并且它使建造防火楼层变得更加简单。这两个变化都可以减少建造的经费。它也让建造更高高度和更长跨度的建筑成为了可能。

Since the weight of modern structures is carried by the steel or concrete frame,the walls do not support the building.They have become 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;the had the solid look of bearing walls.Today,however,curtain walls are often made of lightweight materials such as glass,aluminum,or plastic,in various combinations.

自从现代建筑的重量用钢或者混凝土结构来承重，墙体已经不再用来支撑建筑。它们已经变成用来调节气候和采光的幕墙。在更早的钢或者混凝土框架建筑中，幕墙一般用石材制作。它们具有承重墙结实的性能。然而如今，幕墙通常用像玻璃、铝或者塑料等轻质材料做成用于各种连接中。

Another advance in steel construction is the method of fastening together the beams.For many years the standard method was riveting.A rivet is a bolt with a head that looks like a blunt screw without threads.It is heated,placed in holes through the pieces of steel,and a second head is formed at the other end by hammering it to hold it in place.Riveting has now largely been replaced by welding,the joining together of pieces of steel by melting a steel material between them rnder high heat.

钢结构的另一种改进是将梁紧固在一起的方法。多年来标准方法是铆接技术。铆钉是一种有端部的螺栓看起来像上面没有螺纹钝螺杆。它被加热并通过钢片放置在孔里，并且用锤敲击另一段的第二个端部使其固定到相应位置。铆钉已经广泛被焊接取代，焊接是在高温下使钢片熔化并将它们粘结。

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 being developde.

预应力混凝土已经使建造各种奇形怪状的建筑成为了可能，像一些具有不受任何支撑物阻挡视线的大空间的现代体育场馆。对于这种相对比较新的结构方法的使用一直在不断发展。

The current tendency is to develop lighter materials.Aluminum,for example,weighs much less than steel but has many of the same properties.Aluminum beams have already been used for bridge construction and for the framework of the framework of a few buildings.

现在的趋势是发展更轻的材料。例如铝的重量比钢轻很多但它们有很多共同的特性。铝梁已经被用于桥梁建筑和少量框架结构的建筑中。

Lightweight concretes,another example,are now rapidlly developing throughout the world.They are used for their thermal insulation.The three types are illustrated below:

(a) Concrete made with lightweight aggregates;

(b) Aerated concrete(US gas concretes) foamed by whisking or by some chemical process during casting;

(c) No-fines concretes.

另一个例子，如今轻质混凝土在全世界正在快速发展。它们被用来隔热保温。三个类型说明如下：

（a） 混凝土用轻质骨料做成

（b） 加气混凝土在铸造期间通过搅拌或一些化学方法使其充满气泡。

（c） 混合混凝土

All three types are used for their insulating properties,mainly in housing,where they give high comfort in cold climates and a low cost of cooling in hot climates.In housing,the relative weakness of lightweight concrete walls is unimportant,but it matters in roof slabs,floor slabs and beams.In some locations,some lightweight aggregates cost little more than the best dense aggregates and a large number of floor slabs have therefore been built of lightweight aggregate concrete purely for its weight saving,with mo thought of its insulation value.

三种特性都被用做它们的隔热性能。主要用于一些房屋，在冷的气候下可以给予高度的舒适并且在热的气候下可以以较低的花费降温。在一些住宅，轻质混凝土墙的相对弱点并不重要，但是对屋顶板、地板和梁影响很大。在一些位置，轻质骨料比更致密骨料花费更少并且由于它节省重量许多地板只用轻质骨料制作，而不考虑它的隔热性能。

The lightweigh aggregate reduces the floor dead lad by about 20 per cen resulting in considerable savings in the floor steel in every floor and the roof,as well as in the column steel and(less) in the foundations.Ome London contractor prefers to use lightweight aggregate because it gives him the same weight reduction in the floor slab as the use of hollow tiles,with simpler organization and therefore higher speed and profit.The insulation value of the lightweight aggregate is only important in the roof insulation,which is greatly improved.

轻质骨料可以减少楼板上约20%的静荷载，这是由于它在每个楼板个屋顶减少了许多楼板钢筋的使用，同时柱子里的钢筋和地基里也是。一个伦敦的承包商喜欢用轻质混凝土，因为它使用楼板的空心瓦会帮助他减少同样重量、并且简单组织,从而提高速度和利润. 具有隔热价值的轻骨料仅仅是在屋顶隔热重要,这是屋顶保温很大的改善。

第四单元

Introdution

Mechanics of Materials deals with the response of various bodies, usually called members, to applied forces. In Mechanics of engineering Materials the members have shapes that either exist in actual structures or are being considered for their suitability as parts of proposed engineering structures. The materials in the members have properties that are characteristic of commonly used engineering materials such as steel, aluminum, concrete, and wood.

材料力学处理各种实体的力学反应，这些实体通常被称作构件。在工程材料的力学中，构件所拥有的形状，在实际结构中已经存在，或者正在考虑其是否适合作为拟议的工程结构的部分。在构件中的材料有常用工程材料具有的普遍特性，如钢、铝、混凝土和木材具有的特性。

As you can see already from the variety of materials, forces, and shapes mentioned, Mechanics of Engineering Materials is of interest to all fields of engineering. The engineer uses the principles of Mechanics of Materials to determine if the material properties and the dimensions of a member are adequate to ensure that it can carry its load safely and without excessive distortion. In general, then, we are interested in both the safe load that a member can carry and the associated deformation. Engineering design would be a simple process if the designer could take into consideration the loads and the mechanical properties of the materials, manipulate an equation, and arrive at suitable dimensions. Design is seldom that simple. Usually, on the basis of experience, the designer selects a trial member and then does an analysis to see if that member meets the specified requirements. Frequently, it does not and then a new trial member is selected and the analysis repeated. This design cycle continues until a satisfactory solution is obtained. The number of cycles required to find an acceptable design diminishes as the designer gains experience.

正如您从上述提到的各种材料、荷载和形状中看到的，工程材料力学是各个工程领域感兴趣的。工程师使用材料力学的基本原理来确定材料性质和构件的尺寸在没有过多的失真的情况下是否足以确保安全承担施加在其上的荷载。大体上，我们感兴趣的是构件可以承担的安全负荷和相关联的变形。工程设计可以是一个简单的过程如果工程师将荷载和材料的力学性能考虑在内通过列等式计算出合适的尺寸。设计是很少这么简单。通常，在经验的基础上，设计师选择试验的构件，然后进行分析看该成员是否满足指定的要求。经常，它不能，然后选择一个新的试验构件和重复分析。此设计周期一直继续，直到获得令人满意的解决方案。找到一种可接受的设计所需的周期数目，随着设计师经验的曾加，将会减少。

Design of Axially Loadde Members

To give you some insight into the design cycle ,an extremely simple member will be dealt with first.That member is a prismatic bar with a force,P,acting along its longitudinal axis in the direction such that it tends to slongate the bar.Such a force is referred to as an axial tensile load,and we can readily imagine it trying to pull the fibers apart and to cause failure on a transverse plane .It is safe to assume that all fibers of the bar,in regions from the point of application of the load,are being pulled apart with the same load inensity.With this assumption,the load intensity or stress is uniform on a transverse plane and is given by δ=P/A When P is Neetons and A is in square metres,stress,,is in Newtons per square metre(N/m2),which is by definition Pascals(Pa).

Deflection Due to Bengding

这章的主要内容是建立弯曲方程和求解弯曲方程时的经验方法。由于这类问题的难度和重要性，我们会遇到超静定结构并深入了解。

叠加法时求解静定结构的常用的方法。然而，熟悉叠加法比解决这个问题本身更重要，因为叠加法可应用在应力分析的很多领域，而且在我们今后的研究中还会经常应用。

平面力矩是一种简便的求解各种问题的方法。但是，当我们遇到比较前沿的结构的时候，他就会变得比较麻烦，我们就会需要更加先进的求解方法。就目前的阶段来说我们有充足的时间了解基础的方法。为了阐明在利用力矩平衡公式计算时内力的传递的规律我们学习偏心受压柱，这样我们就可以真正了解直线型和曲线型柱的区别。

这章提供了一个熟悉未知量的机会，他的应用将使静定问题变得非常简单。这仅仅是对已给出的主题的介绍，对于有兴趣的同学来说，还有很多东西需要学习。就我们现阶段来说，要阐明一个真正的限制条件，我们可以通过表达各种各样的断断续续的均布荷载，但是我们不能写出一个集中荷载的荷载函数。如果我们已经进行了下一步，并且解决了集中荷载的问题，我们会遇到奇怪的函数的由来，但是由于本书应用的范围限制了我们进行下一步的研究。

Failure Theories(参考)

In the design of a member subjected to a uniaxial load,the stresses was compared with the stresses to cause failure in test specimens that had also been subjected to uniaxial load. This is the simplest of all design problems;the method is quite adequate,since the nature of the loads and the stresses in the test and in the part being designed are identical. However,we soon encounter cases where the member being designed is not so simple and the stresses are not uniaxial;consider,for example,the stresses in the web of a beam or in a pressure vessel. In these cases we know that the stresses is two-dimensional or biaxial and it may,in other cases,be three-dimensional,or triaxial. For a structure having biaxial or triaxial stresses,how should we check the safety of the design? The most obvious way would be to conduct tests in which specimens are stressed to failure in the same multiaxial manner as in the structure;the allowable multiaxial stress can them be determined by the application of an adequate safety factor. However ,this would require a group of tests for every new set of multiaxial stresses that occurred in design. Such tests are difficult to perform,and the cost of performing them in the required numbers would be prohibitive .Consequently, we need a theory by which the results of the standard uniaxial test can be used to predict the failure of a part made of the same material when the stresses are multiaxial. In other words,we need a failure theory.

其中一个构件在设计中受到的压力载荷作用下,单比较了应力导致失败在测试标本,也受到了单轴负载这是最简单的所有设计问题,该方法是得相当不错,因为大自然的负荷及应力测试,在部分被设计的都是相同的然而,我们很快就遇到案例中,构件被设计的并非如此简单和应力不是单轴,举个例子,考虑网络中的种种压力,梁的或压力容器在这种情况下我们知道为二维和应力条件并可在其他情况下,是三维,或三轴它构成二轴或三轴应力有,我们应该如何检查安全的设计吗?最明显的办法就是在测试失败强调标本是在同一多轴方式在结构;允许多轴应力能够确定一个适当的安全系数的应用然而,这将需要一组测试,为每一个新的多轴应力发生在设计这些测试是困难的成本的表现,以及执行规定编号就太高,我们需要一套理论. 因此,我们需要一个理论,标准单向的结果测试可以被用来预言失败的一部分做同样材料应力是多轴。换句话说,我们需要是失败的理论。

To illustrate the need for a failure theory,let us consider a cylindrical pressure vessel. To aviod unnecessary complications,we will consider in judging the adequate of the design. In this approach we tacitly assumed that the maximum stress could be treated as a uniaxial stress and that it alone determined the safety of the design. The longitudinal stress was not considered although it may,without our knowledge,have had an influence on strength .It happens that our approach in this case is acceptable,but,in a biaxial state of stress,the second strss is not always inconsequential and an understanding of failure theory is necessary in order to avoid making some serious errors.

说明需要破坏理论,让我们来看一个圆柱压力容器为了避免不必要的并发症,我们将考虑在判断适当的设计在这种方式的时候,我们默许假定最大压力会被当作一个单轴应力和而个人安全设计的决定未考虑纵向压力尽管可能,没有我们的知识,有影响的力量,这种事情经常发生,我们的方法在这种情况下是可以接受的,但是,在混凝土构件的受力状况,第二个突出并不总是无关紧要,破坏理论的理解是为了避免作出一些严重的错误。

Unfortunately,as we will discover ,no single theory will be found to apply in all cases; for example,theories that are satisfactory for ductile materials are not acceptable for brittle materials. We will also find that one of the best theories is too complex for everyday use and that most designers prefer a simpler theory that introduces a small but safeside error.

不幸的是,我们将会发现,没有一种理论将被证明适用于所有情形;例如,均能满足理论不接受韧性材料为质材料我们也会发现最好的一种理论是非常复杂的适合于每天使用,同时,大多数设计师喜欢简单的理论,介绍了一个规模虽小但safeside错误。

In developing the various failuer theories,we cannot avoid three-dimensional effects,but we will treat only those cases in which one of the stresses is zero,thus avoiding complications that would tend to obscure the important part of the theories. This is not a serious limitation,since in engineering practice most problems are reduced to the biaxial stress state for design. When shear stresses occur along with normal stresses,the principal stresses are determined .Thus,for practical purposes,we need to consider failuer in a material subjected to two nonzero normal stresses while the third normal stress is zero. For ease in designating those principal stresses we will use numerical subscripts;δ1 and δ2 being the nonzero stresses stresses and δ3 being zero.

在发展中各种各样的失败理论,我们不可能避免三维的影响,不过,我们将对待的情况只有的压力之一为零,因此避免并发症,就会倾向于模糊理论的重要组成部分这不是一个严重的限制,因为在工程实践大多数问题归结为二轴应力设计状态当发生剪切应力与正常重音,确定主应力,所以工作用于实际目的,我们需要考虑失败在物质受到两个非零的应力当第3个正常应力为零为使指定那些主应力数值子脚是否被;我们将使用是δ1和δ2应力和δ3零应力为零。(参考截止)

We cannot discuss failure theory until we have defined failure. We might take the obvious definition that a material has failed when it has broken into two or more parts. However, it has already been pointed out that in most applications a member would be unserviceable due to excessive distortion long before it actually ruptured. Consequently, we will relate failure to yielding and consider that a material has failed when it will no longer return to its original shape upon release of the loads. In a simple tensile test we would then say that a ductile material has failed when the material begins to yield. Then for uniaxial stress, failure occurs when the stress reaches the yield stress, бy, in either tension or compression.

直到我们定义失败，我们才能讨论破坏理论。我们可能把一种材料的破坏定义为明显地碎成两部分或者更多块。然而，在大部分加载情形下一个构件可能会因为过度变形而失效已经被指出，在它实际破碎之前。因此，我们把屈服与破坏联系起来，考虑当一种材料在卸载之后不能再恢复到原来的形状时这种材料就破坏了。在一个简单拉伸测试中我们会说一种韧性的材料在它开始屈服的时候就破坏了。然后对于单轴应力，当应力达到屈服极限бy时发生破坏，无论是在压缩或者拉伸情形下。

Brittle materials fail by a different mechanism and will be discussed after the theories for ductile materials have been presented.

脆性材料失效机制与韧性材料不同，在韧性材料理论被阐述之后将会进行讨论。

第一单元 土木工程

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 accomplish 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.

从根本上，工程是一个以最终产品为导向的行业，它具有创新、成本意识，同时也注意到人为因素。 它与创建新的实体、 设备或解决方案有关：新工艺、新材料、一个改进的动力来源、任务的一项更有效地安排，用以完成所需的目标或创建一个新的结构。 工程是也不仅仅关心获得经济的解决方案。最终，人类安全才是一个最重要的考虑因素。

Engineering is concerned with the use of abstract scientific ways of thinking and of defining real world problems. The use of idealizations and development of procedures for establishing bounds within which behavior can be ascertained are part of the process.

工程关心的是，使用抽象的科学方法思考和定义现实世界的问题。理想化的使用和发展建立可以确定行为的边界的程序，是过程的一部分。

Many problems, by their very nature, can’t be fully described—even after the fact, much less at the outset. Yet acceptable engineering solutions to these 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, processes, or solutions. And this, too, is all a part of engineering.

很多的问题，就其本身的性质而言，不能完全被描述 — — 即使这一事实，在其开始之前。然而还必须找到对于这些问题可接受的工程解决方案，来满足预定的需求。直觉或判断是建立可能的替代策略、 流程或解决方案的关键因素。。而这也是工程的一部分。

Civil engineering is one of the most diverse branches of engineering. The civil engineer plans, designs, constructs, and maintains a large variety of structures and facilities for public, commercial and industrial use. These 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 sewage and waste disposal systems that add to our convenience and safeguard our health.

土木工程是工程的最多样化的分支机构之一。土木工程师计划、设计、施工，和维护大量的结构和公共、商业和工业使用的设施。这些结构包括住宅，办公室和工厂大厦；公路、铁路、机场、隧道、桥梁、港口、渠道和管道。在其他大多数的国家它们还包括运输系统许多其他设施，以及将为我们的生活带来便利的和维护我们的健康污水及废物处理系统。

The term “civil engineer” did not come into use until about 1750, when John Smeaton, the builder of famous Eddystone lighthouse near Plymouth, England, is said to have begun calling himself a “civil engineer” to distinguish himself from the military engineers of his time. However, the profession is as old as civilization.

直到大约1750年，人们才开始使用“土木工程师”这一术语。约翰.斯密顿在英格兰普利茅斯附近，建造了著名的埃迪斯通灯塔的建造师，开始自称为“土木工程师"来将自己与当时的军事工程师区分开。然而，土木工程这个职业却像文明一样古老。

第三单元 建筑材料（重点）

The principal 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 tarlike substance, or some other binding agent. The Greeks and Romans sometimes used iron rods or clamps to strengthen their building. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rusted away. The Romans also used a natural cement called pozzolana, made from volcanic ash, that became as hard as stone under water.早期的主要建筑材料包括木材以及像砖、石块、瓦片等类似材料的石材。砖层或夹层用砂浆、像焦油状的沥青或其他粘合剂年节在一起，有时希腊和罗马人用铁杆或夹钳加固建筑物。例如，帕台农神庙的柱子上就有一些钻孔，现在钻孔中的铁已经锈蚀尽了。罗马人常用一种称做白榴火山灰的水泥，他的成份是火山灰，在水中它会变得像石头一样坚硬。

Modern cement, called Portland cement, was invented in 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. 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 of shapes. And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances complement each other.

被称为波特兰的现代水泥于1824年制成的，它是粘土和石灰石的混合物，他们在加热时会裂化成粉末在施工现场或附近，与砂，骨料，水，搅拌制成水泥，水泥因组成成分比例的不同会有强度和重量的差异，水泥的用途非常多，它们以浇筑、泵送，甚至喷射成各种形状，由于钢筋有很好的抗拉强度，水泥有较高的抗压强度。所以这两种材料相互补充。

Prestressed concrete is an improved form of reinforcement. Steel rods are bent into the shapes to give them the necessary degree of tensile strength. They are then used to prestress concrete, usually by one of two different methods. The first is to leave channels in a concrete beam that correspond to the shapes of the steel rods. When the rods are run through the channels, they are then bonded to the concrete by filling the channels with grout, a thin mortar or binding agent. In the other (and more common) method, the prestressed steel rods are placed in the lower part of a form that corresponds to the shape of the finished structure, and the concrete is poured around them. Prestressed concrete uses less steel and less concrete. Because it is so economical, it is a highly desirable material.

预应力混凝土是混凝土一种强度增大的形式，钢筋屈服所需要抗拉强度的形状。然后用于使混凝土受预应力，通常运用两种方法之一。第一种实在混凝土梁中留出预应力钢筋通道，当预应力钢筋穿过通道时，通过往其中填充灰浆，一种薄砂浆或粘合剂。把其粘固在其中。另一种更常用的方法是，将预应力钢筋固定在已设计好的结构模型向相应的部分，然后围绕它浇筑混凝土，预应力混凝土用较少的钢筋和混凝土所以它很经济，是一种非常理想的材料。

第四单元 材料力学

Mechanics of Materials deals with the response of various bodies, usually called members, to applied forces. In Mechanics of engineering Materials the members have shapes that either exist in actual structures or are being considered for their suitability as parts of proposed engineering structures. The materials in the members have properties that are characteristic of commonly used engineering materials such as steel, aluminum, concrete, and wood.

材料力学处理各种实体的力学反应，这些实体通常被称作构件。在工程材料的力学中，构件所拥有的形状，在实际结构中已经存在，或者正在考虑其是否适合作为拟议的工程结构的部分。在构件中的材料有常用工程材料具有的普遍特性，如钢、铝、混凝土和木材具有的特性。

As you can see already from the variety of materials, forces, and shapes mentioned, Mechanics of Engineering Materials is of interest to all fields of engineering. The engineer uses the principles of Mechanics of Materials to determine if the material properties and the dimensions of a member are adequate to ensure that it can carry its load safely and without excessive distortion. In general, then, we are interested in both the safe load that a member can carry and the associated deformation. Engineering design would be a simple process if the designer could take into consideration the loads and the mechanical properties of the materials, manipulate an equation, and arrive at suitable dimensions. Design is seldom that simple. Usually, on the basis of experience, the designer selects a trial member and then does an analysis to see if that member meets the specified requirements. Frequently, it does not and then a new trial member is selected and the analysis repeated. This design cycle continues until a satisfactory solution is obtained. The number of cycles required to find an acceptable design diminishes as the designer gains experience.

正如您从上述提到的各种材料、荷载和形状中看到的，工程材料力学是各个工程领域感兴趣的。工程师使用材料力学的基本原理来确定材料性质和构件的尺寸在没有过多的失真的情况下是否足以确保安全承担施加在其上的荷载。大体上，我们感兴趣的是构件可以承担的安全负荷和相关联的变形。工程设计可以是一个简单的过程如果工程师将荷载和材料的力学性能考虑在内通过列等式计算出合适的尺寸。设计是很少这么简单。通常，在经验的基础上，设计师选择试验的构件，然后进行分析看该成员是否满足指定的要求。经常，它不能，然后选择一个新的试验构件和重复分析。此设计周期一直继续，直到获得令人满意的解决方案。找到一种可接受的设计所需的周期数目，随着设计师经验的曾加，将会减少，。

We cannot discuss failure theory until we have defined failure. We might take the obvious definition that a material has failed when it has broken into two or more parts. However, it has already been pointed out that in most applications a member would be unserviceable due to excessive distortion long before it actually ruptured. Consequently, we will relate failure to yielding and consider that a material has failed when it will no longer return to its original shape upon release of the loads. In a simple tensile test we would then say that a ductile material has failed when the material begins to yield. Then for uniaxial stress, failure occurs when the stress reaches the yield stress, бy, in either tension or compression.

直到我们定义失败，我们才能讨论破坏理论。我们可能把一种材料的破坏定义为明显地碎成两部分或者更多块。然而，在大部分加载情形下一个构件可能会因为过度变形而失效已经被指出，在它实际破碎之前。因此，我们把屈服与破坏联系起来，考虑当一种材料在卸载之后不能再恢复到原来的形状时这种材料就破坏了。在一个简单拉伸测试中我们会说一种韧性的材料在它开始屈服的时候就破坏了。然后对于单轴应力，当应力达到屈服极限бy时发生破坏，无论是在压缩或者拉伸情形下。

Brittle materials fail by a different mechanism and will be discussed after the theories for ductile materials have been presented.

脆性材料失效机制与韧性材料不同，在韧性材料理论被阐述之后将会进行讨论。

第五单元 结构分析

A structure consists of a series of connected parts used to support loads. Notable example include buildings, bridges, towers ,tanks, and construction. Structural analysis consists of a variety of mathematical procedures for determining such quantites as the member forces and various structural displacements as a structure responds to its loads. Estimating realistic loads for the structure considering its use and location is often a part of structural analysis.

结构是由一系列相互联结的部分组成并用来承担荷载。典型的例子包括：建筑、桥梁、塔、水箱、大坝等。建造任一这些结构都要求有计划、分析、设计、和建造。结构分析包括各种各样的决定大量构件的材料强度和数学工序，还有各种各样的结构排布以支撑它的荷载。考虑结构的用途和位置以评估它的实际荷载也经常是结构分析的一部分。

In the real sense an exact analysis of a structure can never be carried out since estimates always have to be made of the loadings and the strength of the materials composing the structure .Furthermore, points of application for the loadings must also be estimated. It is important, therefore , that the structural engineers develop the ability to model or idealize a structure so that he or she can perform a practical force analysis of the members.

在真正意义上，在组成结构的材料的荷载和强度没有被评估之前，一个正确的结构分析永远不会被执行。而且，荷载的应用也必须评估，这是很重要的，因而，结构工程师将有能力去模型化或理想化一个结构。从而使工程师能推演构件的实际受力分析。

Structural members are joined together in various ways depending on the intent of the designer. The two types of joints most often specified are the pin connection and the fixed joint. A pin-connected joint allows some freedom for slight rotation, whereas the fixed joint allows no relative rotation between the connected members . In reality , however ,all connections exhibit some stiffness toward joint rotations, owing to friction and material behavior . When selecting a particular model for each support or joint, the engineer must be aware of how the assumptions will affect the actual performance of the member and whether the assumptions are reasonable for the structural design. In reality ,all structural supports actually exert distributed surface loads on their contacting members. The resulants of these load distributions are often idealized as the concentrated forces and moments, since the surface area over which the distributed load acts is considerably smaller than the total surface area of the connecting members. The ability to reduce an actual structure to an idealized form can only be gained by experience. In engineering practice, if it becomes doubtful as to how to model a structure or transfer the loads to the members, it is best to consider several idealized structures and loadings and then design the actual structure so that it can resist the loadings in all the idealized models.

依照设计师的意图，结构构件以各种各样的方式联结在一起。两种常常详述的连接方式是铰接和刚接。铰接点允许构件间有微小的自由转动，儿刚节点则不允许相连构件间的相对转动。实际上，所有的连接方式都显示出对连接处旋转的阻碍作用，因为有摩擦力和材料引力。当给每个支撑或连接方式选择一个代表性模型的时候，工程师必须注意到那些假定怎么样影响构件的实际表现和那些假定对于结构设计是否合理。实际上，所有的结构支持的都是相互连接构件的表面均布荷载。这些荷载的作用效果常常理想化为集中荷载和集中弯矩，尽管作用在构件表面上的均布荷载比连接处的荷载小很多。能减少一个理想化形状的某一确定构件的能力只能从经验中获得。在工程实际中，如果怎样来模拟一个结构或将荷载传递到杆件难以确定是，最好考虑几个理想结构，然后设计实际结构使得它在所有理想模型中都能抵抗荷载。

第七单元

混凝土和钢筋混凝土作为建筑材料在每个国家都被广泛的使用。在许多国家，包括美国和加拿大在内，钢筋混凝土在土木工程建设中是一种主导的结构材料。钢筋混凝土被全球广泛使用源于钢筋和混凝土中的砾石、沙子和水泥等组分的广泛可用性，以及混凝土施工需要的技术相对较低，并且与其他建筑形式相比，钢筋混凝土更经济。混凝土和钢筋混凝土被用于桥梁、各种房屋、地下结构、水箱、电视塔、海洋石油勘探、工业结构、水坝乃至船舶。

钢筋混凝土构件的施工涉及到按照构件形状支模具。模具必须要有足够的强度用以承受湿混凝土的自重和静力水压，以及工人、混凝土手推车、风等所加的各种外力。在混凝土浇筑过程中，钢筋被放置在模具中并占用一定空间。在混凝土硬化后，模具被拆去。

防火等级 在建筑物中的人群被撤离以及大火被扑灭期间，建筑物的结构必须能够承受一定的大火的不利影响，并保持稳定。在没有特殊防火装置和其他设施时，混凝土建筑就固有1到3小时的耐火等级。刚结构或木结构的建筑必须设有防火材料以达到相似的耐火等级

土木工程专业英语翻译