土木工程類外文文獻(xiàn)翻譯

1、畢 業(yè) 設(shè) 計（外文文獻(xiàn)翻譯）題 目: 新余學(xué)院學(xué)生實(shí)習(xí)樓系 別：土木與建筑學(xué)院專 業(yè)：2012級建工方向姓 名：汪楠學(xué) 號：2012102745指導(dǎo)教師：李新猷外文翻譯Abstract:To study the application of continuum structural topology optimization methods to real engineering structures,an optimization method for an optimal topology design of multistory steel frame bracing systems

2、is presented.On a sensitivity analysis,an element removal criterion for continuum structures with stress and multi-displacement constraints under multiple lateral loading conditions is proposed.A concept of mean thickness of a design domain is provided to ensure the reasonableness of optimal results

3、.In the proposed optimization method,the optimal design of an unbraced steel frame without displacement constraints is performed firstly,and then the optimal topology of a bracing system for the multistory steel frame considering displacement constraints is obtained by using evolutionary structural

4、optimization and the given removal criterion,and finally the optima layout of the bracing system is interpreted as bracing members.An example of 3-bay 12-story plane steel frame shows that it is effective for the given optimization method in the optimal design of bracing systems for multistory steel

5、 frames. Key words:steel frame;bracing system;continuum;topology optimization;evolutionary structural optimization2.1 Reinforced ConcretePlain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The

6、plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the cement/water mix, resulting in hardened concrete. The finished product has high compressive strength, and low resistance to tension, such that its tensile stren

7、gth is approximately one tenth lf its compressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete element.It is this deviation in the composition of a reinforces concre

8、te section from the homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two components of the heterogeneous reinforced concrete section are to be so arranged and proportioned that optimal use is made of the materials invo

9、lved. This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent ingredients are properly proportioned, the finished product becomes strong, durable, and, in combination with the reinforcing bars, adaptable for use as main mem

10、bers of any structural system.The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and hardened concrete. For beams, columns, and walls, the f

11、orms should be well oiled after cleaning them, and the reinforcement should be cleared of rust and other harmful materials. In foundations, the earth should be compacted and thoroughly moistened to about 6 in. in depth to avoid absorption of the moisture present in the wet concrete. Concrete should

12、always be placed in horizontal layers which are compacted by means of high frequency power-driven vibrators of either the immersion or external type, as the case requires, unless it is placed by pumping. It must be kept in mind, however, that over vibration can be harmful since it could cause segreg

13、ation of the aggregate and bleeding of the concrete.Hydration of the cement takes place in the presence of moisture at temperatures above 50F. It is necessary to maintain such a condition in order that the chemical hydration reaction can take place. If drying is too rapid, surface cracking takes pla

14、ce. This would result in reduction of concrete strength due to cracking as well as the failure to attain full chemical hydration.It is clear that a large number of parameters have to be dealt with in proportioning a reinforced concrete element, such as geometrical width, depth, area of reinforcement

15、, steel strain, concrete strain, steel stress, and so on. Consequently, trial and adjustment is necessary in the choice of concrete sections, with assumptions based on conditions at site, availability of the constituent materials, particular demands of the owners, architectural and headroom requirem

16、ents, the applicable codes, and environmental reinforced concrete is often a site-constructed composite, in contrast to the standard mill-fabricated beam and column sections in steel structures.A trial section has to be chosen for each critical location in a structural system. The trial section has

17、to be analyzed to determine if its nominal resisting strength is adequate to carry the applied factored load. Since more than one trial is often necessary to arrive at the required section, the first design input step generates into a series of trial-and-adjustment analyses.The trial-and adjustment

18、procedures for the choice of a concrete section lead to the convergence of analysis and design. Hence every design is an analysis once a trial section is chosen. The availability of handbooks, charts, and personal computers and programs supports this approach as a more efficient, compact, and speedy

19、 instructional method compared with the traditional approach of treating the analysis of reinforced concrete separately from pure design.2.2 Earthwork Because earthmoving methods and costs change more quickly than those in any other branch of civil engineering, this is a field where there are real o

20、pportunities for the enthusiast. In 1935 most of the methods now in use for carrying and excavating earth with rubber-tyred equipment did not exist. Most earth was moved by narrow rail track, now relatively rare, and the main methods of excavation, with face shovel, backacter, or dragline or grab, t

21、hough they are still widely used are only a few of the many current methods. To keep his knowledge of earthmoving equipment up to date an engineer must therefore spend tine studying modern machines. Generally the only reliable up-to-date information on excavators, loaders and transport is obtainable

22、 from the makers.Earthworks or earthmoving means cutting into ground where its surface is too high ( cuts ), and dumping the earth in other places where the surface is too low ( fills). Toreduce earthwork costs, the volume of the fills should be equal to the volume of the cuts and wherever possible

23、the cuts should be placednear to fills of equal volume so as to reduce transport and double handlingof the fill. This work of earthwork design falls on the engineer who lays out the road since it is the layout of the earthwork more than anything else which decides its cheapness. From the available m

24、aps ahd levels, the engineering must try to reach as many decisions as possible in the drawing office by drawing cross sections of the earthwork. On the site when further information becomes available he can make changes in jis sections and layout,but the drawing lffice work will not have been lost.

25、 It will have helped him to reach the best solution in the shortest time.The cheapest way of moving earth is to take it directly out of the cut and drop it as fill with the same machine. This is not always possible, but when it canbe done it is ideal, being both quick and cheap. Draglines, bulldozer

26、s and face shovels an do this. The largest radius is obtained with the dragline,and the largest tonnage of earth is moved by the bulldozer, though only over short distances.The disadvantages of the dragline are that it must dig below itself, it cannot dig with force into compacted material, it canno

27、t dig on steep slopws, and its dumping and digging are not accurate.Face shovels are between bulldozers and draglines, having a larger radius of action than bulldozers but less than draglines. They are anle to dig into a vertical cliff face in a way which would be dangerous tor a bulldozer operator

28、and impossible for a dragline. Each piece of equipment should be level of their tracks and for deep digs in compact material a backacter is most useful, but its dumping radius is considerably less than that of the same escavator fitted with a face shovel.Rubber-tyred bowl scrapers are indispensable

29、for fairly level digging where the distance of transport is too much tor a dragline or face shovel. They can dig the material deeply ( but only below themselves ) to a fairly flat surface, carry it hundreds of meters if need be, then drop it and level it roughly during the dumping. For hard digging

30、it is often found economical to keep a pusher tractor ( wheeled or tracked ) on the digging site, to push each scraper as it returns to dig. As soon as the scraper is full,the pusher tractor returns to the beginning of the dig to heop to help the nest scraper.Bowl scrapers are often extremely powerf

31、ul machines;many makers build scrapers of 8 cubic meters struck capacity, which carry 10 m heaped. The largest self-propelled scrapers are of 19 m struck capacity ( 25 m heaped )and they are driven by a tractor engine of 430 horse-powers.Dumpers are probably the commonest rubber-tyred transport sinc

32、e they can also conveniently be used for carrying concrete or other building materials. Dumpers have the earth container over the front axle on large rubber-tyred wheels, and the container tips forwards on most types, though in articulated dumpers the direction of tip can be widely varied. The small

33、est dumpers have a capacity of about 0.5 m , and the largest standard types are of about 4.5 m . Special types include the self-loading dumper of up to 4 m and the articulated type of about 0.5 m . The distinction between dumpers and dump trucks must be remembered .dumpers tip forwards and the drive

34、r sits behind the load. Dump trucks are heavy, strengthened tipping lorries, the driver travels in front lf the load and the load is dumped behind him, so they are sometimes called rear-dump trucks. 2.3 Safety of StructuresThe principal scope of specifications is to provide general principles and co

35、mputational methods in order to verify safety of structures. The “ safety factor ”, which according to modern trends is independent of the nature and combination of the materials used, can usually be defined as the ratio between the conditions. This ratio is also proportional to the inverse of the p

36、robability ( risk ) of failure of the structure. Failure has to be considered not only as overall collapse of the structure but also as unserviceability or, according to a more precise. Common definition. As the reaching of a “ limit state ” which causes the construction not to accomplish the task i

37、t was designed for. There are two categories of limit state :(1)Ultimate limit sate, which corresponds to the highest value of the load-bearing capacity. Examples include local buckling or global instability of the structure; failure of some sections and subsequent transformation of the structure in

38、to a mechanism; failure by fatigue; elastic or plastic deformation or creep that cause a substantial change of the geometry of the structure; and sensitivity of the structure to alternating loads, to fire and to explosions.(2)Service limit states, which are functions of the use and durability of the

39、 structure. Examples include excessive deformations and displacements without instability; early or excessive cracks; large vibrations; and corrosion.Computational methods used to verify structures with respect to the different safety conditions can be separated into:(1)Deterministic methods, in whi

40、ch the main parameters are considered as nonrandom parameters.(2)Probabilistic methods, in which the main parameters are considered as random parameters.Alternatively, with respect to the different use of factors of safety, computational methods can be separated into:(1)Allowable stress method, in w

41、hich the stresses computed under maximum loads are compared with the strength of the material reduced by given safety factors.(2)Limit states method, in which the structure may be proportioned on the basis of its maximum strength. This strength, as determined by rational analysis, shall not be less

42、than that required to support a factored load equal to the sum of the factored live load and dead load ( ultimate state ).The stresses corresponding to working ( service ) conditions with unfactored live and dead loads are compared with prescribed values ( service limit state ) . From the four possi

43、ble combinations of the first two and second two methods, we can obtain some useful computational methods. Generally, two combinations prevail:(1)deterministic methods, which make use of allowable stresses.(2)Probabilistic methods, which make use of limit states.The main advantage of probabilistic a

44、pproaches is that, at least in theory, it is possible to scientifically take into account all random factors of safety, which are then combined to define the safety factor. probabilistic approaches depend upon : (1)Random distribution of strength of materials with respect to the conditions of fabric

45、ation and erection ( scatter of the values of mechanical properties through out the structure );(2)Uncertainty of the geometry of the cross-section sand of the structure ( faults and imperfections due to fabrication and erection of the structure );(3)Uncertainty of the predicted live loads and dead

46、loads acting on the structure;(4)Uncertainty related to the approximation of the computational method used ( deviation of the actual stresses from computed stresses ).Furthermore, probabilistic theories mean that the allowable risk can be based on several factors, such as :(1)Importance of the const

47、ruction and gravity of the damage by its failure;(2)Number of human lives which can be threatened by this failure;(3)Possibility and/or likelihood of repairing the structure;(4)Predicted life of the structure.All these factors are related to economic and social considerations such as：(1)Initial cost

48、 of the construction; (2)Amortization funds for the duration of the construction; (3)Cost of physical and material damage due to the failure of the construction; (4)Adverse impact on society; (5)Moral and psychological views. The definition of all these parameters, for a given safety factor, allows

49、construction at the optimum cost. However, the difficulty of carrying out a complete probabilistic analysis has to be taken into account. For such an analysis the laws of the distribution of the live load and its induced stresses, of the scatter of mechanical properties of materials, and of the geom

50、etry of the cross-sections and the structure have to be known. Furthermore, it is difficult to interpret the interaction between the law of distribution of strength and that of stresses because both depend upon the nature of the material, on the cross-sections and upon the load acting on the structu

51、re. These practical difficulties can be overcome in two ways. The first is to apply different safety factors to the material and to the loads, without necessarily adopting the probabilistic criterion. The second is an approximate probabilistic method which introduces some simplifying assumptions ( s

52、emi-probabilistic methods ) .中文翻譯摘要：為了研究連續(xù)型拓?fù)鋬?yōu)化理論在實(shí)際工程中的應(yīng)用，該文給出了一種多層鋼框架支撐體系連續(xù)型拓?fù)鋬?yōu)化設(shè)計方法?；陟`敏度分析，探討了連續(xù)體結(jié)構(gòu)在多工況荷載作用下、同時受應(yīng)力和多位移約束的拓?fù)鋬?yōu)化刪除準(zhǔn)則。為保證拓?fù)鋬?yōu)化結(jié)果的合理性，提出了設(shè)計區(qū)域平均厚度的概念。在該文給出的優(yōu)化設(shè)計方法中，首先在不考慮位移約束的情況下對無支撐鋼框架進(jìn)行優(yōu)化設(shè)計，然后在有位移約束的條件下采用漸進(jìn)結(jié)構(gòu)優(yōu)化算法和刪除準(zhǔn)則對支撐體系進(jìn)行連續(xù)型拓?fù)鋬?yōu)化設(shè)計，并將獲得的支撐最優(yōu)拓?fù)錁?gòu)形轉(zhuǎn)化成相應(yīng)的桿件。通過一個3跨12層鋼框架支撐體系的拓?fù)鋬?yōu)化設(shè)計實(shí)例驗(yàn)證了該

53、文給出的鋼框架支撐體系連續(xù)型拓?fù)鋬?yōu)化設(shè)計方法的有效性。關(guān)鍵詞：鋼框架；支撐體系；連續(xù)型；拓?fù)鋬?yōu)化；漸進(jìn)結(jié)構(gòu)優(yōu)化1.1鋼筋混凝土素混凝土是由水泥、水、細(xì)骨料、粗骨料（碎石或；卵石）、空氣，通常還有其他外加劑等經(jīng)過凝固硬化而成。將可塑的混凝土拌合物注入到模板內(nèi)，并將其搗實(shí)，然后進(jìn)行養(yǎng)護(hù)，以加速水泥與水的水化反應(yīng)，最后獲得硬化的混凝土。其最終制成品具有較高的抗壓強(qiáng)度和較低的抗拉強(qiáng)度。其抗拉強(qiáng)度約為抗壓強(qiáng)度的十分之一。因此，截面的受拉區(qū)必須配置抗拉鋼筋和抗剪鋼筋以增加鋼筋混凝土構(gòu)件中較弱的受拉區(qū)的強(qiáng)度。由于鋼筋混凝土截面在均質(zhì)性上與標(biāo)準(zhǔn)的木材或鋼的截面存在著差異，因此，需要對結(jié)構(gòu)設(shè)計的基本原理進(jìn)行修改

54、。將鋼筋混凝土這種非均質(zhì)截面的兩種組成部分按一定比例適當(dāng)布置，可以最好的利用這兩種材料。這一要求是可以達(dá)到的。因混凝土由配料攪拌成濕拌合物，經(jīng)過振搗并凝固硬化，可以做成任何一種需要的形狀。如果拌制混凝土的各種材料配合比恰當(dāng)，則混凝土制成品的強(qiáng)度較高，經(jīng)久耐用，配置鋼筋后，可以作為任何結(jié)構(gòu)體系的主要構(gòu)件。澆筑混凝土所需要的技術(shù)取決于即將澆筑的構(gòu)件類型，諸如：柱、梁、墻、板、基礎(chǔ)，大體積混凝土水壩或者繼續(xù)延長已澆筑完畢并且已經(jīng)凝固的混凝土等。對于梁、柱、墻等構(gòu)件，當(dāng)模板清理干凈后應(yīng)該在其上涂油，鋼筋表面的銹及其他有害物質(zhì)也應(yīng)該被清除干凈。澆筑基礎(chǔ)前，應(yīng)將坑底土夯實(shí)并用水浸濕6英寸，以免土壤從新澆的

55、混凝土中吸收水分。一般情況下，除使用混凝土泵澆筑外，混凝土都應(yīng)在水平方向分層澆筑，并使用插入式或表面式高頻電動振搗器搗實(shí)。必須記住，過分的振搗將導(dǎo)致骨料離析和混凝土泌漿等現(xiàn)象，因而是有害的。水泥的水化作用發(fā)生在有水分存在，而且氣溫在50F以上的條件下。為了保證水泥的水化作用得以進(jìn)行，必須具備上述條件。如果干燥過快則會出現(xiàn)表面裂縫，這將有損與混凝土的強(qiáng)度，同時也會影響到水泥水化作用的充分進(jìn)行。設(shè)計鋼筋混凝土構(gòu)件時顯然需要處理大量的參數(shù)，諸如寬度、高度等幾何尺寸，配筋的面積，鋼筋的應(yīng)變和混凝土的應(yīng)變，鋼筋的應(yīng)力等等。因此，在選擇混凝土截面時需要進(jìn)行試算并作調(diào)整，根據(jù)施工現(xiàn)場條件、混凝土原材料的供應(yīng)

56、情況、業(yè)主提出的特殊要求、對建筑和凈空高度的要求、所用的設(shè)計規(guī)范以及建筑物周圍環(huán)境條件等最后確定截面。鋼筋混凝土通常是現(xiàn)場澆注的合成材料，它與在工廠中制造的標(biāo)準(zhǔn)的鋼結(jié)構(gòu)梁、柱等不同，因此對于上面所提到的一系列因素必須予以考慮。對結(jié)構(gòu)體系的各個部位均需選定試算截面并進(jìn)行驗(yàn)算，以確定該截面的名義強(qiáng)度是否足以承受所作用的計算荷載。由于經(jīng)常需要進(jìn)行多次試算，才能求出所需的截面，因此設(shè)計時第一次采用的數(shù)值將導(dǎo)致一系列的試算與調(diào)整工作。選擇混凝土截面時，采用試算與調(diào)整過程可以使復(fù)核與設(shè)計結(jié)合在一起。因此，當(dāng)試算截面選定后，每次設(shè)計都是對截面進(jìn)行復(fù)核。手冊、圖表和微型計算機(jī)以及專用程序的使用，使這種設(shè)計方法

57、更為簡捷有效，而傳統(tǒng)的方法則是把鋼筋混凝土的復(fù)核與單純的設(shè)計分別進(jìn)行處理。1.2土方工程由于和土木工程中任何其他工種的施工方法與費(fèi)用相比較，土方挖運(yùn)的施工方法與費(fèi)用的變化都要快得多，因此對于有事業(yè)心的人來說，土方工程是一個可以大有作為的領(lǐng)域。在1935年，目前采用的利用輪胎式機(jī)械設(shè)備進(jìn)行土方挖運(yùn)的方法大多數(shù)還沒有出現(xiàn)。那是大部分土方是采用窄軌鐵路運(yùn)輸，在這目前來說是很少采用的。當(dāng)時主要的開挖方式是使用正鏟、反鏟、拉鏟或抓斗等挖土機(jī)，盡管這些機(jī)械目前仍然在廣泛應(yīng)用，但是它們只不過是目前所采用的許多方法中的一小部分。因此，一個工程師為了使自己在土方挖運(yùn)設(shè)備方面的知識跟得上時代的發(fā)展，他應(yīng)當(dāng)花費(fèi)一些

58、時間去研究現(xiàn)代的機(jī)械。一般說來，有關(guān)挖土機(jī)、裝載機(jī)和運(yùn)輸機(jī)械的唯一可靠而又最新的資料可以從制造廠商處獲得。土方工程或土方挖運(yùn)工程指的是把地表面過高處的土壤挖去（挖方），并把它傾卸到地表面過低的其他地方（填方）。為了降低土方工程費(fèi)用，填方量應(yīng)該等于挖方量，而且挖方地點(diǎn)應(yīng)該盡可能靠近土方量相等的填方地點(diǎn)，以減少運(yùn)輸量和填方的二次搬運(yùn)。土方設(shè)計這項(xiàng)工作落到了從事道路設(shè)計的工程師的身上，因?yàn)橥练焦こ痰脑O(shè)計比其他任何工作更能決定工程造價是否低廉。根據(jù)現(xiàn)有的地圖和標(biāo)高，道路工程師應(yīng)在設(shè)計繪圖室中的工作也并不是徒勞的。它將幫助他在最短的時間內(nèi)獲得最好的方案。費(fèi)用最低的運(yùn)土方法是用同一臺機(jī)械直接挖方取土并且卸

59、土作為填方。這并不是經(jīng)?？梢宰龅降?，但是如果能夠做到則是很理想的，因?yàn)檫@樣做既快捷又省錢。拉鏟挖土機(jī)。推土機(jī)和正鏟挖土機(jī)都能做到這點(diǎn)。拉鏟挖土機(jī)的工作半徑最大。推土機(jī)所推運(yùn)的圖的數(shù)量最多，只是運(yùn)輸距離很短。拉鏟挖土機(jī)的缺點(diǎn)是只能挖比它本身低的土，不能施加壓力挖入壓實(shí)的土壤內(nèi)，不能在陡坡上挖土，而且挖。卸都不準(zhǔn)確。正鏟挖土機(jī)介于推土機(jī)和拉鏟挖土機(jī)的之間，其作用半徑大于推土機(jī)，但小于拉鏟挖土機(jī)。正鏟挖土機(jī)能挖取豎直陡峭的工作面，這種方式對推土機(jī)司機(jī)來說是危險的，而對拉鏟挖土機(jī)則是不可能的。每種機(jī)械設(shè)備應(yīng)該進(jìn)行最適合它的性能的作業(yè)。正鏟挖土機(jī)不能挖比其停機(jī)平面低很多的土，而深挖堅實(shí)的土壤時，反鏟挖土機(jī)最適