畢業(yè)設(shè)計(jì)外文翻譯----結(jié)構(gòu)分析

1、<p><b>　　結(jié)構(gòu)分析</b></p><p><b>　　一．建筑結(jié)構(gòu)</b></p><p>　　就工程的實(shí)質(zhì)而言，建筑結(jié)構(gòu)可定義為：以保持形狀和穩(wěn)定為目的的各個基本構(gòu)件的組合體。其基本目的是抵抗作用在建筑物上的各種荷載并把它傳到地基。</p><p>　　從建筑學(xué)的角度來講，建筑結(jié)構(gòu)要做的更多。它與建

2、筑風(fēng)格是不可分割的，在不同程度上是一種建筑風(fēng)格的體現(xiàn)。如能巧妙地設(shè)計(jì)建筑結(jié)構(gòu)，則可建立或加強(qiáng)建筑空間與建筑平面之間的格調(diào)與節(jié)奏。它在直觀上可以是顯性的或隱性的。它能產(chǎn)生和諧體或?qū)φ阵w。它可能既局限又開放。不幸的是在一些情況下，它不能被忽視，它是存在的。</p><p>　　結(jié)構(gòu)設(shè)計(jì)還必須維持建筑風(fēng)格。物理學(xué)和數(shù)學(xué)的原理及工具為區(qū)分在結(jié)構(gòu)上的合理與不合理的形式提供了依據(jù)。藝術(shù)家有時可以不必考慮科學(xué)就能畫出圖形，但建

3、筑師卻不行。</p><p>　　在建筑結(jié)構(gòu)中至少三項(xiàng)內(nèi)容存在：穩(wěn)定性 強(qiáng)度和剛度 經(jīng)濟(jì)性</p><p>　　在上述三項(xiàng)要求中，很明顯維持建筑物形狀的穩(wěn)定性要求是首選。一座不穩(wěn)定的建筑結(jié)構(gòu)意味著有不平衡的力或失去平衡狀態(tài)，并且會導(dǎo)致建筑結(jié)構(gòu)整體或部分產(chǎn)生加速度。</p><p>　　強(qiáng)度的要求意味著材料的選擇要能抵抗荷載和變形引起的應(yīng)

4、力。實(shí)際上，通常都提供一個安全系數(shù)為了在預(yù)計(jì)的荷載作用下，給定材料的應(yīng)力不會接近破壞應(yīng)力，被稱為剛度的材料特性，需與強(qiáng)度要求一起考慮。剛度不同于強(qiáng)度，因?yàn)樗婕昂奢d作用下結(jié)構(gòu)應(yīng)變的大小和變形的程度。材料如具有很高的強(qiáng)度，但剛度較低，在外力作用下會因變形過大而失效。</p><p>　　建筑結(jié)構(gòu)的經(jīng)濟(jì)性指的不僅僅是所用材料的費(fèi)用。建筑經(jīng)濟(jì)是一個復(fù)雜的問題，其中包括原材料、制作、安裝和維修。設(shè)計(jì)和施工中人工費(fèi)及能源消

5、耗的費(fèi)用也要考慮。施工的速度和工程成本（利息）也是需要考慮的因素。對大多數(shù)設(shè)計(jì)情況，不僅僅只考慮一種建筑材料，經(jīng)常存在一些有競爭性的選擇，而具體應(yīng)選擇哪種并不明顯。</p><p>　　除了這三種最基本要求之外，其他幾種因素也值得重視。首先，結(jié)構(gòu)或結(jié)構(gòu)體系必須和建筑物的功能相關(guān)而不應(yīng)該與建筑風(fēng)格相矛盾。例如，線性功能要求顯性結(jié)構(gòu)，所以把保齡球場的頂部蓋成圓形是不適合的。劇院必須是較大跨度、中間沒有障礙的結(jié)構(gòu)，而高

6、檔商店卻不是這樣。簡單地說，結(jié)構(gòu)必須具有維護(hù)空間的功能。</p><p>　　第二，結(jié)構(gòu)必須防火。很顯然，結(jié)構(gòu)體系必須能保持完整直到內(nèi)部人員安全撤離為止。建筑規(guī)范詳細(xì)規(guī)定了建筑物的某些部位抵抗熱量而不倒塌的時間。用于那些構(gòu)件的結(jié)構(gòu)材料必須自身具有防火性或者用耐火材料。所規(guī)定的防火等級將取決于一系列因素，它包括建筑空間的占有和使用；建筑物的尺寸及建筑物的位置。</p><p>　　第三，結(jié)構(gòu)

7、應(yīng)與建筑物的循環(huán)系統(tǒng)很好地結(jié)合。它不應(yīng)與給排水管道，通風(fēng)系統(tǒng)或人的活動空間相矛盾（這是最重要的）。很顯然，各種建筑系統(tǒng)在設(shè)計(jì)時必須相互協(xié)調(diào)。對任何一個系統(tǒng)的設(shè)計(jì)，可以一步一步地按順序進(jìn)行，而對所有系統(tǒng)的設(shè)計(jì)則采用并行方式來完成。從空間上來講，在一座建筑物中所有的構(gòu)件之間都是相互依存的。</p><p>　　第四，結(jié)構(gòu)在心理上及外觀上必須給人一種安全感。在風(fēng)荷載作用下晃動得很厲害的高層框架雖然沒有危害，但仍然不適宜

8、居住。彈性太大的輕質(zhì)樓蓋系統(tǒng)可能給居住者很不舒服的感覺。沒有窗欞的巨大玻璃窗戶是相當(dāng)安全的，但對居住在樓房里的人來說，特別是當(dāng)他站在臨街40層高樓的大玻璃窗前時，總會感到極不安全。</p><p>　　有時建筑師必須有意采取積極措施來增加建筑結(jié)構(gòu)外表的強(qiáng)度和堅(jiān)固性。外觀的安全性也許比真實(shí)表達(dá)建筑結(jié)構(gòu)更重要，因?yàn)闆]有受過訓(xùn)練的人是不能分清真實(shí)的和感覺中的安全。</p><p>　　二．結(jié)構(gòu)模

9、型以及分析與結(jié)構(gòu)設(shè)計(jì)的關(guān)系</p><p>　　結(jié)構(gòu)分析是確定在給定荷載下結(jié)構(gòu)中產(chǎn)生的力和變形以便使結(jié)構(gòu)設(shè)計(jì)得合理，并能檢查現(xiàn)有結(jié)構(gòu)的安全狀況。</p><p>　　在結(jié)構(gòu)設(shè)計(jì)中，必須先從結(jié)構(gòu)的概念開始假設(shè)一種結(jié)構(gòu)形式，然后再進(jìn)行分析。這樣做能確定構(gòu)件的尺寸以及所需要的鋼筋，為了a）承受設(shè)計(jì)荷載而不出現(xiàn)損壞或過大變形（正常使用或工作狀態(tài)）；b)防止在規(guī)定的超載施加到結(jié)構(gòu)上以前倒塌（安全或極

10、限狀態(tài)）</p><p>　　由于通常在工作荷載作用下，結(jié)構(gòu)處于彈性狀態(tài)，建立在彈性假設(shè)基礎(chǔ)上的結(jié)構(gòu)理論就適用于正常狀態(tài)。結(jié)構(gòu)的倒塌通常在遠(yuǎn)遠(yuǎn)超出材料彈性范圍，超出臨界點(diǎn)后才會發(fā)生，因而建立在材料非彈性狀態(tài)基礎(chǔ)上的極限強(qiáng)度理論是合理確定結(jié)構(gòu)安全性所必需的。但是，彈性理論可用來確定延性結(jié)構(gòu)強(qiáng)度的安全近似值（塑性下限逼近法），在鋼筋混凝土設(shè)計(jì)中通常采用這種方法。基于這種原因，在本段中僅僅采用結(jié)構(gòu)的彈性理論。</

11、p><p>　　仔細(xì)地觀察所有結(jié)構(gòu)都是三維構(gòu)件的組合體，對其進(jìn)行精確的分析，甚至在理想狀態(tài)下，也是一個很難的工作，即使專門從事這個的人員也很難做到。由于這種原因，分析人員工作的一個重要部分是將實(shí)際結(jié)構(gòu)和荷載狀態(tài)簡化成一個容易合理分析的模型。</p><p>　　這樣，結(jié)構(gòu)框架系統(tǒng)可分解成板和樓蓋梁，樓蓋梁是由立柱支撐的交叉梁系，立柱將荷載傳到基礎(chǔ)。因?yàn)閭鹘y(tǒng)的結(jié)構(gòu)分析不能分析板的作用，所以經(jīng)常理

12、想化成類似于梁的條形系統(tǒng)。同樣，常用的方法不能處理三維框架系統(tǒng)，因此通過平面結(jié)構(gòu)組合系統(tǒng)建立整個結(jié)構(gòu)的模型，分別加以分析?，F(xiàn)代的矩陣—計(jì)算機(jī)法可以分析整個系統(tǒng)從而革新了結(jié)構(gòu)分析，這樣可對荷載作用下結(jié)構(gòu)的性能作出更可靠的預(yù)測。</p><p>　　實(shí)際荷載狀態(tài)也是很難確定的和很難客觀表達(dá)的，為了分析，必須把它簡化。例如，橋梁結(jié)構(gòu)上的交通荷載主要是動力的和隨機(jī)性的，通常理想化成靜態(tài)行駛的標(biāo)準(zhǔn)卡車或分布荷載，以用來模擬

13、實(shí)際產(chǎn)生的最危險的荷載狀態(tài)。</p><p>　　同樣，連續(xù)梁有時簡化為簡支梁，剛性節(jié)點(diǎn)簡化為鉸接點(diǎn)，填充墻可以忽略，把剪力墻當(dāng)成梁；在決定如何建立一個比較客觀，同時又簡單的結(jié)構(gòu)模型，分析人員必須記住每個理想化模型都會使結(jié)果有更多的可能。分析得越客觀，產(chǎn)生的信心越大，所取得安全系數(shù)（或忽略的因素）會越小。這樣，除非規(guī)范條例控制，工程師必須估算出結(jié)構(gòu)精確分析與結(jié)構(gòu)中可能節(jié)省的費(fèi)用相比，是否合算。</p>

14、<p>　　三．結(jié)構(gòu)動力分析的主要目的</p><p>　　本節(jié)的主要目的是：介紹任何給定形式的結(jié)構(gòu)在承受人移動荷載時所產(chǎn)生的應(yīng)力和撓度的分析方法。從某種意義上講，這個目的可以認(rèn)為是，把通常只適用于靜荷載的結(jié)構(gòu)分析標(biāo)準(zhǔn)方法加以推廣，使之也可以在動荷載的分析中加以應(yīng)用。對此，靜荷載可以被看作僅僅是動荷載的一種特殊形式。然而，在線性結(jié)構(gòu)分析中，更為方便的是區(qū)分施加荷載中的靜力和動力分量，然后分別計(jì)算對每

15、種荷載的反應(yīng)，最后將兩個反應(yīng)分量疊加得出總效應(yīng)，當(dāng)進(jìn)行這樣處理時，靜力的和動力的分析方法在性質(zhì)上是根本不同的。</p><p>　　為了上述目的，“動的”這個詞可以簡單地被定義為隨時間而改變的，這樣，動荷載就是大小、方向、作用點(diǎn)隨時間而改變的荷載。同樣，在動荷載下的結(jié)構(gòu)反應(yīng)，即所產(chǎn)生的撓度和應(yīng)力，也是隨時間而改變的或動的。</p><p>　　兩種基本不同的方法可以計(jì)算動荷載下的結(jié)構(gòu)反應(yīng)：

16、確定的和非確定的。在任何給定的情況下，選取哪種方法，將取決于荷載是如何規(guī)定的。如果荷載隨時間的變化是完全已知的，即使它是高度變化不定的或者其性質(zhì)是不規(guī)則變化的，我們將把它稱為非隨機(jī)動荷載；而任何特定的結(jié)構(gòu)體系在非隨機(jī)動荷載下的反應(yīng)分析通常定義為確定分析。另一種情況，如果荷載隨時間的變化不是完全已知的，但可從統(tǒng)計(jì)方面來進(jìn)行定義，這種荷載則稱為隨機(jī)動荷載，而非確定分析對應(yīng)于隨機(jī)動荷載下的反應(yīng)分析。</p><p>　

17、　一般來說，動荷載下的結(jié)構(gòu)反應(yīng)主要是用結(jié)構(gòu)的位移來表示的。這樣，確定分析能導(dǎo)出相應(yīng)于規(guī)定荷載下的位移—時間過程；結(jié)構(gòu)的其他確定反應(yīng)，如應(yīng)力、應(yīng)變、內(nèi)力等等，通常作為分析的次要方面，可從前面所建立的位移模式求得。另一方面，非確定分析提供有關(guān)位移的統(tǒng)計(jì)信息，而這種位移是由統(tǒng)計(jì)定義的荷載所產(chǎn)生的。由于這時位移隨時間的變化是不確定的，因而，其他的反應(yīng)，如應(yīng)力、內(nèi)力等，必須用特定的非確定分析方法直接計(jì)算，而不是由所得位移來計(jì)算。</p>

18、;<p>　　結(jié)構(gòu)動力學(xué)問題在兩個重要的方面不同于它的靜荷載問題。第一個不同點(diǎn)，根據(jù)定義，動力問題具有隨時間而變化的特性。由于荷載和反應(yīng)隨時間而變化，顯然動力問題不像靜力問題那樣具有單一的結(jié)果，而必須建立相應(yīng)于反應(yīng)時程中感興趣的全部時間的一系列解答。因此，動力分析顯然要比靜力分析更復(fù)雜且更花費(fèi)時間。</p><p>　　然而，靜力問題和動力問題還有一個更重要的區(qū)別，如圖1所示。如果一簡支梁承受一靜荷

19、載，如圖所示，則它的彎矩、剪力及撓曲形狀直接依賴于給定的荷載，而且可根據(jù)所建立的力的平衡原理用求出。另一方面，如果荷載是動力的，如圖所示，則所產(chǎn)生的梁的位移與加速度有關(guān)，這些加速度又產(chǎn)生與其反向的慣性力。于是，在圖中梁的彎矩和剪力不僅要平衡外荷載，而且要平衡由于梁的加速度所引起的慣性力。</p><p><b>　　慣性力</b></p><p>　　圖1 動荷載與靜

20、荷載的區(qū)別:</p><p><b>　　靜荷載; 動荷載</b></p><p>　　以這種方式抵抗結(jié)構(gòu)加速度引起的慣性力是結(jié)構(gòu)動力學(xué)問題的一個最重要的區(qū)別特征。一般來說，如果慣性力是結(jié)構(gòu)內(nèi)部彈性力所平衡的總荷載中的一個很明顯的部分，則在解題時必須考慮問題的動力特性。另一方面。如果運(yùn)動是非常慢，以致于慣性力可以忽略不計(jì)，那么即使荷載和反應(yīng)可能隨時間變化，對任何所需瞬

21、時的分析，仍可用靜力結(jié)構(gòu)分析的方法來解決。</p><p><b>　　UNIT SIX</b></p><p>　　Text Structural Analysis</p><p>　　一．Structure of Buildings</p><p>　　Considering only

22、the engineering essentials, the structure of a building can be defined as the assemblage of those parts which exist for the purpose of maintaining shape and stability. Its prim- ary purpose is to resist any loads applie

23、d to the building and to transmit those to the ground.</p><p>　　In terms of architecture, the structure of a building is and does much more than that. It is an inseparable part of the building form and to va

24、rying degrees is a generator of that form. Used skillf- ully, the building structure can establish or reinforce orders and rhythms among the architectural v- olumes and planes. It can be visually dominant or recessive. I

25、t can develop harmonies or conflicts. It can be both confining and emancipating. And, unfortunately in some cases, it cannot be ignored. </p><p>　　The structure must also be engineered to maintain the archit

26、ectural form. The principles and tools of physics and mathematics provide the basis for differentiating between rational and irration- al forms in terms of construction. Artists can sometimes generate shapes that obviate

27、 any considera- tion of science, but architects cannot.</p><p>　　There are at least three items that must be present in the structure of a building:</p><p><b>　　stability</b></p&g

28、t;<p>　　strength and stiffness</p><p><b>　　economy</b></p><p>　　Taking the first of the three requirements, it is obvious that stability is needed to maintain sh- ape. An unst

29、able building structure implies unbalanced forces or a lack of equilibrium and a conesq- uent acceleration of the structure or its pieces.</p><p>　　The requirement of strength means that the materials select

30、ed to resist the stresses generated by the loads and shapes of the structure(s) must be adequate. Indeed, a"factor of safety" is usually provided so that under the anticipated loads, a given material is not str

31、essed to a level even close to its rupture point. The material property called stiffness is considered with the requirement of streng- th. Stiffness is different from strength in that it directly involves how much a stru

32、cture strai</p><p>　　Economy of a building structure refers to more than just the cost of the materials used. Construction economy is a complicated subject involving raw materials, fabrication, erection, and

33、 maintenance. Design and construction labor costs and the costs of energy consumption must be considered. Speed of construction and the cost of money (interest) are also factors. In most design situations, more than one

34、structural material requires consideration. Competi tire alternatives almost always exist, and</p><p>　　Apart from these three primary requirements, several other factors are worthy of emphasis. F- irst, the

35、 structure or structural system must relate to the building's function. It should not be in conf- lict in terms of form. For example, a linear function demands a linear structure, and therefore it wo- uld be improper

36、 to roof a bowling alley with a dome. Similarly, a theater must have large, unobstru- ucted spans but a fine restaurant probably should not. Stated simply, the structure must be app</p><p>　　Second, the stru

37、cture must be fire-resistant. It is obvious that the structural system must be a- ble to maintain its integrity at least until the occupants are safely out. Building codes specify the nu- mber of hours for which certain

38、parts of a building must resist the heat without collapse. The struct- ural materials used for those elements must be inherently fire-resistant or be adequately protected by fireproofing materials. The degree of fire r

39、esistance to be provided will depend upon a </p><p>　　Third, the structure should integrate well with the buildingˊs circulation systems. It should not be in conflict with the piping systems for water and wa

40、ste, the ducting systems for air, or (most important) the movement of people. It is obvious that the various building systems must be coordin- ated as the design progresses. One can design in a sequential step-by-step ma

41、nner within any one system, but the design of all of them should move in a parallel manner toward completion. Spatially, all th</p><p>　　Fourth, the structure must be psychologically safe as well as physical

42、ly safe. A high-rise fra- me that sways considerably in the wind might not actually be dangerous but may make the building uninhabitable just the same. Lightweight floor systems that are too"bouncy" can make th

43、e users very uncomfortable. Large glass windows, uninterrupted by dividing mullions, can be quite safe but will appear very insecure to the occupant standing next to one 40 floors above the street.</p><p>　　

44、Sometimes the architect must make deliberate attempts to increase the apparent strength or solidness of the structure. This apparent safety may be more important than honestly expressing the buildingˊs structure, because

45、 the untrained viewer cannot distinguish between real and perceived safety.</p><p>　　二．Modeling of Structures and Relation of Analysis and Design</p><p>　　Structural analysis is the process of d

46、etermining the forces and deformations in structures due to specified loads so that the structure can be designed rationally, and so that the state of safety of exi- sting structures can be checked. </p><p>

47、　　In the design of structures,it is necessary to start with a concept leading to a configuration which can then be analyzed. This is done so members can be sized and the needed reinforcing determined, in order to. a)carr

48、y the design loads without distress or excessive deformations (serviceability or w- orking condition); and b) to prevent collapse before a specified overload has been placed on the str- ucture (safety or ultimate conditi

49、on).</p><p>　　Since normally elastic conditions will prevail under working loads, a structural theory based on the assumptions of elastic behavior is appropriate for determining serviceability conditions. Co

50、llap- se of a structure will usually occur only long after the elastic range of the materials has been excee- ded at critical points, so that an ultimate strength theory based on the inelastic behavior of the mate- rials

51、 is necessary for a rational determination of the safety of a structure against collaps</p><p>　　Looked at critically,all structures are assemblies of three-dimensio- nal elements, the exact ana- lysis of wh

52、ich is a forbidding task even under ideal conditions and impossible to contemplate under conditions of professional practice. For this reason, an important part of the analyst's work is the si- mplification of the ac

53、tual structure and loading conditions to a model which is susceptible to ration- al analysis.</p><p>　　Thus, a structural framing system is decomposed into a slab and floor beams which in turn fra- me into g

54、irders carried by columns which transmit the loads to the foundations. Since traditional structural analysis has been unable to cope with the action of the slab, this has often been idealized into a system of strips acti

55、ng as beams. Also,long-hand methods have been unable to cope with thr- ee-dimensional framing systems, so that the entire structure has been modeled by a system of planar subas</p><p>　　Actual loading condit

56、ions are also both difficult to determine and to express realistically, and m- ust be simplified for purposes of analysis. Thus, traffic loads on a bridge structure, which are essen- tially both of dynamic and random nat

57、ure, are usually idealized into statically moving standard truc- ks, or distributed loads, intended to simulate the most severe loading conditi- ons occurring in pract- ice. </p><p>　　Similarly, continuous b

58、eams are sometimes reduced to simple beams, rigid joints to pin-joints, filler-walls are neglected, shear walls are considered as beams in deciding how to model a structure so as to make it reasonably realistic but at th

59、e same time reasonably simple, the analyst must reme- mber that each such idealization will make the solution more suspect. The more realistic the analys- is, the greater will be the confidence which it inspires, and the

60、 smaller may be the safety factor (or</p><p>　　三．Fundamental Objective of Structural Dynamics Analysis</p><p>　　The primary purpose of this praagraph is to present methods for analyzing the stre

61、sses and deflections developed in any given type of structure when it is subjected to an arbitrary dynamic loading. In one sense, the objective may be considered to be the extension of standard methods of structural an-

62、alysis, which generally are concerned only with static loading ,to permit consideration of dynamic loads as well. In this context ,the static-loading condition may be looked upon merely as a special</p><p>　

63、　For the purposes of this presentation the term dynamic may be defined simply as timevarying, t- hus a dynamic load is any load of which the magnitude, direction, or position varies with time. Sim- ilarly,the structural

64、response to a dynamic load ,i. e. the resulting deflections and stresses,is also ti- me-varying ,or dynamic.</p><p>　　Two basically different approaches are available for evaluating structural response to dy

65、namic loads:deterministic and nondeterministic. The choice of method to be used in any given case depen- ds upon how the loading is defined. If the time variation of loading is fully known, even though it may be highly o

66、scillatory or irregular in character, it will be referred to herein as a prescribed dyn- amic loading and the analysis of the response of any specified structural system to a prescribed dyna</p><p>　　In gen

67、eral, the structural response to any dynamic loading is expressed basically in terms of the displacements of the structure. Thus a deterministic analysis leads to a displacement-time history corresponding to the prescrib

68、ed loading history ;other aspects of the deterministic structural respo- nse,such as stresses,strains,internal forces,etc. ,are usually obtained as a secondary phase of the ana- lysis, from the previously established dis

69、placement patterns. On the other hand,a nondeterminist</p><p>　　A structural-dynamic problem differs from its static-loading counterpart in two important respe- cts. The first difference to be noted, by defi

70、nition, is the time-varying nature of the dynamic proble- m. Because the load and the response vary with time,it is evident that a dynamic problem does not have a single solution,as a static problem does. Instead the ana

71、lyst must establish a succession of so- lutions corresponding to all times of interest in the response history. Thus a dynamic analysis </p><p>　　However,a more fundamental distinction between static and dy

72、namic problems is illustrated in Fig. 1. If a simple beam is subjected to a static load ,as shown in Fig. , its internal mome- nts and shears and deflected shape depend directly upon the given load and can be computed fr

73、om by established principles of force equilibrium. On the other hand, if the load is applied dy- namically,as shown in Fig., the resulting displacements of the beam are associated with accelra- tions which produce inert

74、</p><p>　　Inertia forces</p><p>　　Fig. 1 Basic difference between static and dynamic loads:</p><p>　　static loading; dynamic loading</p><p>　　Inertia forces which resis

75、t accelerations of the structure in this way are the most important disti- nguishing characteristic of a structural-dynamics problem. In general, if the inertia forces represent a signifieant portion of the total load eq

76、uilibrated by the internal elastic forces of the structure, then the dynamic character of the problem must be accounted for in its solution. On the other hand,if the motions are so slow that the inertia force's,are n