外文翻譯--組合作用的基礎(chǔ)及抗剪連接

1、<p>　　畢 業(yè) 設(shè) 計（論 文）外 文 參 考 資 料 及 譯 文</p><p>　　譯文題目： </p><p>　　學生姓名： 學　　號： </p><p>　　?！　I(yè)：

2、 </p><p>　　所在學院： </p><p>　　指導教師： </p><p>　　職　　稱： </p><p>　　年

3、 月 日</p><p>　　Fundamentals of Composite Action and Shear Connection</p><p>　　The evolution of satisfactory design methods for composite beams has been a slow process, requiring much theoretic

4、al and experimental work in order' to provide economic and, at the same time, safe design criteria. The purpose of this Chapter is to describe in some detail the more important fundamentals which have to be taken int

5、o account in the design of composite structures.</p><p>　　Historically the first analysis of a composite section was based on the conventional assumptions of the elastic theory which limit the stresses in th

6、e component 'materials to a certain proportion of their 'failure stresses (yield in the case of steel, crushing in the case of concrete). The assumptions inherent in the elastic method are similar to those for or

7、dinary reinforced concrete. In recent' years the concepts of the ultimate load design philosophy have been applied to composite action and </p><p>　　Before dealing in detail with the two design approache

8、s (elastic and ultimate load) basic points require consideration.</p><p>　　A clear understanding of the way in which the component materials, steel concrete and shear connection react to applied load is an e

9、ssential preliminary to full analysis of the composite section. Of primary importance are the stress strains relationships, which must of necessity be the product of carefully controlled experiment. These experimental re

10、sults are not generally suited to direct application and so simplifications and idealisations are adopted in practice. The use of computers has made</p><p>　　Composite action between steel and concrete impli

11、es some interconnection between the two materials which will transfer shear between them. In reinforced concrete members the natural bond of concrete to steel is often sufficient to do this, although cases do arise in wh

12、ich additional anchorage is required. The fully encased filler joist also has a large embedded area which is adequate for full shear transfer. However, the situation is quite different with the common type of composite b

13、eam in whic</p><p>　　It has. been pointed out that the paradoxical situation exists that if shear connection is provided it may in fact not come into operation because the natural bond takes all the is provi

14、ded it may in fact not come into operation because the natural bond takes all the shear force, and so `if sufficient shear connectors are provided then they are unnecessary'.</p><p>　　The evolution of sh

15、ear connection devices has been slow and has necessitated a large volume of experimental work on the static and fatigue properties of a wide range of mainly mechanical connectors.</p><p>　　It soon appeared c

16、lear to early research workers that some form of connector fixed to the top flange of the beam and anchored into the slab was necessary. Caughey and Scott in 1929 proposed using, amongst other things, projecting bolt end

17、s. Since then a wide variety of types of mechanical connector has been used in experiment and practice. To some extent the proliferation of types has been .the result of steel fabricators using sections which came easily

18、 to hand, since initially a purpose-made s</p><p>　　In any mechanical connection system it is possible to identify parts which transfer horizontal shear and parts which tie the slab down to the beam. General

19、ly, horizontal shear resistance is the ruling criterion of shear connector action and with this in mind mechanical connectors may be classified into three main groups-rigid, flexible and bond.</p><p>　　Limit

20、 State Design of Brickwork</p><p>　　The basic aim of structural design is to ensure that a structure should fulfill its intended function throughout its lifetime without excessive deflection, cracking or col

21、lapse, and this aim must of course be met with due regard to economy.The designer is assisted in his task by the availability of a code of practice which is based on accumulated experience and research. Up to the present

22、 time, such codes have sought to ensure the safety and serviceability of masonry structures by specifying per</p><p>　　In recent years a more rational procedure has been evolved for dealing with structural s

23、afety and serviceability through consideration of the relevant "limit states“ . A structure, or part of a structure, reaches a limit state when it becomes incapable of fulfilling its function or when it no longer sa

24、tisfies the conditions for which it was designed. Two categories of limit state normally have to be considered, namely , ultimate limit states corresponding to failure or collapse and serviceabilit</p><p>　　

25、The general method of applying the limit states approach to the design of structures is outlined in a publication of the International Organization for Standardization in which the criterion for a satisfactory design is

26、expressed in terms of design loading effects (S * )and design strengths (R * )as follows </p><p>　　(1) </p><p&

27、gt;　　Design loading effects are determined from the characteristic actions from the relationship</p><p>　　S * = effects of (） (2)

28、 </p><p>　　where γf is a multiplier (or partial safety factor) and is a characteristic load which, if defined in statistical terms , is given by</p><p>　　where is the value of the m

29、ost unfavourable load with a 50 per cent probability of its being exceeded once in the expected life of the structure δ is the standard deviation of the distribution of the .maximum loading k is a coefficient depefldin8

30、on a selected probability of maximum loadings being greater than </p><p>　　It is usual to take the characteristic load as that which will have a 5 per cent probability of being exceeded during the lifetime o

31、f the structure.④In many situations, however,statistical data are not available and the characteristic loads have to be based on nominal values given in codes of practice or other regulations.The factorγf is a function o

32、f several</p><p>　　partial coefficients.</p><p>　　which takes account of the possibility of unfavourable deviation of the loads from the characteristic external loads ,thus allowing for abnormal

33、 or unforeseen actions</p><p>　　which takes account of the reduced probability that various loads acting together will a11 be simultaneously at their characteristic values.</p><p>　　which is int

34、ended to allow for possible modification of the load effects due to incorrect design assumptions (for example, introduction of simplified support conditions, hinges, neglect of thermal and other effects which are difficu

35、lt to assess) and constructional discrepancies such as dimensions of cross-section, deviation of columns from the vertical and accidental eccentricities.</p><p>　　Similarly , design strengths of materials, R

36、* , are defined by</p><p><b>　　R * ﹦</b></p><p>　　where -- Rm-ks is the characteristic strength of the material</p><p>　　Rm is the arithmetic mean of test results</p&

37、gt;<p>　　s is the standard deviation </p><p>　　k is a coefficient depending on the probability of obtaining results less than </p><p>　　The characteristic strength of a material is usuall

38、y taken as the 95 per cent confidence limit of the material strength in a relevant test series. The reduction coefficient γm is</p><p>　　a function of two coefficients</p><p>　　which is intended

39、 to cover possible reductions in the strength of the materials in the structure as whole as compared to the characteristic value deduced from the control test specimen</p><p>　　which is intended to cover po

40、ssible weakness of the structure arising from any cause other than the reduction in the strength of the materials allowed for by coefficient γm1, including manufacturing tolerances.</p><p>　　Additionally , I

41、SO 2394 allows for the introduction of a further coefficient which may be applied either to the design values of loadings or material strengths. This coefficient is in turn a function of two partial coefficients</p>

42、;<p>　　which is intended to take account of the nature of the structure and its behaviour , for example, structures or parts of structures in which partial or complete collapse can occur without warning, where red

43、istribution of internal forces is not possible, or where failure of a single element can lead to overall collapse</p><p>　　which is intended to take account of the seriousness of attaining a limit state from

44、 other points of view, for example economic consequences,danger to the community , etc.</p><p>　　Usually γc is incorporated into either γf or γm and therefore does not appear explicitly In design calculation

45、s.</p><p>　　The advantage of the limit state approach is that permits a more rational and flexible assessment of structural safety and serviceability; the various relevant factors are identified and up to a

46、point can be expressed in numerical terms. ⑤Ideally ，loading and strengths should be available in statistical terms but this is seldom possible ，so that characteristic values have to be determined on the basis of availab

47、le evidence .In the case of loads ，the evidence generally results from surveys of bui</p><p>　　組合作用的基礎(chǔ)及抗剪連接</p><p>　　尋求組合梁的滿意設(shè)計方法是一個緩慢的過程。它需要許多理論和試驗工作。以此來提供既經(jīng)濟又安全的設(shè)計準則。這一樣的主要目的是詳細介紹一些在組合結(jié)構(gòu)設(shè)計中必須考

48、慮的重要基本概念。</p><p>　　過去，組合截面的分析最先用的是基于彈性理論的傳統(tǒng)假設(shè)。該理論把材料的應力限制在它們的破損應力（剛才即為其屈服點，混凝土為其壓碎應力的某個比例）的一部分。這種在彈性理論中固有的假設(shè)和普通鋼筋混凝土中的假設(shè)十分相似。近年來，極限荷載設(shè)計理論已被應用到組合結(jié)構(gòu)中，大量的試驗證明，對于均稱的組合截面而言，此方法是安全、經(jīng)濟的。雖然目前極限荷載設(shè)計理論僅僅直接用于建筑結(jié)構(gòu)，而還未用于

49、橋梁中，但不容懷疑，這種限制總有一天會消失的。</p><p>　　在詳細敘述這2種設(shè)計方法（彈性方法和極限荷載方法）之前需要先介紹一些基本概念。</p><p>　　清楚地了解組合梁中各部件：鋼梁、混凝土板及剪力連接鍵對外荷載作用的反應是透徹分析組合截面的基礎(chǔ)。其中最重要的是應力應變關(guān)系曲線。而該曲線是必須精心試驗的結(jié)果。這些試驗結(jié)果并不能直接應用。在實際工作，必須采用簡化和理想化的曲線

50、。因此應用計算機就有可能減少這些所要的假定。由于計算機“實驗”可應用復雜的多的材料應力—應變關(guān)系。</p><p>　　鋼與混凝土間的組合作用是指在兩種材料間傳遞剪力的相互作用。在普通鋼筋混凝土構(gòu)建中雖然有時確有需要附加錨固的情況，但混凝土與鋼筋間的天然粘結(jié)力足以起到這種作用。完全埋置在混凝土內(nèi)的現(xiàn)澆肋梁有著較大的錨固面積，這足能傳遞剪力，然而，這完全不同于普通組合梁。在組合梁中，混凝土板置于鋼梁上翼緣之上或?qū)?/p>

51、梁的上翼緣完全包裹在混凝土板內(nèi)。最初在鋼梁和混凝土板解除面上確有粘結(jié)和摩擦力來傳遞一些剪力。但上面的混凝土板有和鋼梁上下分離的趨勢，這樣就不能傳遞水平剪力.超載或振動荷載引起的疲勞作用將破壞混凝土板與鋼梁間的天然粘結(jié)九這種粘結(jié)力一旦遭到破壞就不可恢復。這種不確定的抗剪連接效果顯然不符合要求，所以就需要有意在混凝土板和鋼梁間設(shè)一些連接鍵以傳遞水平剪力和避免二者分離.在抗剪連接中存在著天然粘結(jié)力，但不能依靠它，而且在任何情況下都要計算它的數(shù)

52、值也是不可能的。這樣就必須設(shè)置剪力連接鍵傳遞所有的水平剪力。</p><p>　　這里應指出一種矛盾現(xiàn)象:若設(shè)里了剪力連接鍵，天然瑞諾力會承擔全部的剪力而使設(shè)置的剪力連接鍵不起作用，所以，如果提供足夠的剪力連接鍵，又是不必要的。</p><p>　　抗剪連接鍵的研究發(fā)展比較緩慢，它需廣泛地對大量機械式連接鍵進行靜力和疲勞試驗。</p><p>　　早期的研究者很快就

53、清楚地發(fā)現(xiàn):有必要把某種連接鍵一端固定于鋼梁的上翼緣之上，另一端錨人混凝土板中。1929年Caughey和Scott在眾多的連接鍵形式中，提出用栓釘連接鍵.從此，各種機械式的抗剪連接鍵得到廣泛應用。從某種程度上說，連接鍵形式的多</p><p>　　樣化是由于鋼結(jié)構(gòu)制造商想使用容易找到的部件，因為在研究初期還沒有專用抗剪這一目的而特制的剪力連接鍵。</p><p>　　在任何一種機械式連接

54、體系中，它可以使傳遞水平剪力和避免使板和梁分開這兩個作用統(tǒng)一在一起。一般來說，水平抗剪作用是衡量抗剪連接鍵的標準。據(jù)此，機械式剪力連接鍵可以分為三大類，即剛性的，柔性的和粘結(jié)式的。</p><p>　　砌體結(jié)構(gòu)的極限狀態(tài)設(shè)計法</p><p>　　結(jié)構(gòu)設(shè)計的基本目的是保證其在使用期間不發(fā)生過大的變形、開裂或倒塌，完成預定的功能要求，當然還要適當考慮其經(jīng)濟性。設(shè)計者在其工作中可借助于靠積累的

55、經(jīng)驗和科研成果形成的現(xiàn)行規(guī)范。到目前為止，這些規(guī)范通過規(guī)定各種材料及其組合體的允許應力來摸索保證砌體結(jié)構(gòu)的安全性和適用性.因而，規(guī)范一般給出磚和砂漿組合范圍內(nèi)的基本抗壓應力，在特定情況下基本應力再根據(jù)砌體的長細比和荷載的偏心程度予以調(diào)整。基本應力根據(jù)墻體或墻垛的試驗求得，而極限應力則由足以避免在使用荷載作用下發(fā)生開裂的適當?shù)陌踩禂?shù)求得。因此，從這種意義上講，砌體結(jié)構(gòu)設(shè)計總是與極限強度和正常使用極限狀態(tài)聯(lián)系在一起的。</p>

56、<p>　　近年來，通過考慮相應的“極限狀態(tài)”，即結(jié)構(gòu)或其一部分達到一種不鴿完成其功能的狀態(tài)或結(jié)構(gòu)不再滿足設(shè)計規(guī)定條件的狀態(tài)，形成了一種解決結(jié)構(gòu)安全性和適用性的更合理的設(shè)計方法。通常要考慮兩類極限狀態(tài)，即結(jié)構(gòu)將發(fā)生破壞或倒塌的承載力極限狀態(tài)，及結(jié)構(gòu)將產(chǎn)生過大變形或裂縫的正常使用極限狀態(tài)。</p><p>　　國際標準化組織出版的規(guī)范中對結(jié)構(gòu)的極限狀態(tài)設(shè)計方法作了概述，就是用設(shè)計荷載效應（S*)和設(shè)計

57、強度（R*）給出了滿足設(shè)計準則的表達式，即</p><p><b>　?。?）</b></p><p>　　設(shè)計荷載效應根據(jù)作用的特點由下式給出</p><p><b>　　的效應</b></p><p>　　其中為擴大系數(shù)（或分項安全系數(shù)），按統(tǒng)計學術(shù)語為特征荷載，由下式確定</p>

58、<p><b>　?。?）</b></p><p>　　式中 —是在結(jié)構(gòu)使用期內(nèi)具有50%失效概率的最不利荷載值;</p><p>　　—是最大荷載分布的標準差，</p><p>　　K —為最大荷載大于的概率系數(shù)。</p><p>　　在結(jié)構(gòu)的使用期間，特征荷載的取值通常具有5%的失效概率，但在多種情況下，

59、由于統(tǒng)計資料不足，在實用規(guī)范或其他規(guī)程中，只給出其名義值。是一系列分項系數(shù)的函數(shù)。</p><p>　　考慮了特征荷載可能不利的離散分布，亦即允許存在荷載變異或不可預見的荷載作用；</p><p>　　考慮了各種荷載同時達到其特征值在概率上的可能性的降低；</p><p>　　考慮了由于設(shè)計假設(shè)不正確（例如采用簡化的支承條件、鉸、忽略溫差等其他難以估計的因素）和截面

60、尺寸、柱子傾斜及偶然偏心等施工誤差，用以對荷載效應進行可能的修正。</p><p>　　與此類似，材料的設(shè)計強度R*定義為</p><p><b>　?。?)</b></p><p>　　式中 — 是材料的特征強度；</p><p>　　— 為材料強度試驗結(jié)果的算術(shù)平均值；</p><p>&l

61、t;b>　　S — 為標準差；</b></p><p>　　k — 為試驗結(jié)果低于的概率系數(shù)。</p><p>　　材料的特征強度通常根據(jù)相應的試驗結(jié)界取為具有95%保證率的值。材料強度的降低系數(shù)是以下兩個系數(shù)的函數(shù)。</p><p>　　用以考慮結(jié)構(gòu)中的材料與試件相比可能的強度降低；</p><p>　　用以考慮由系數(shù)決定

62、的材料強度的降低外，包括制造誤差在內(nèi)的其他因素可能對結(jié)構(gòu)的削弱。</p><p>　　另外，IS02394還允許采用另一個系數(shù)，它可用以調(diào)整荷載或材料強度的設(shè)計值。該系數(shù)也是以下兩分項系數(shù)的函數(shù)。</p><p>　　用以考慮結(jié)構(gòu)的特征和性能，例如結(jié)構(gòu)或結(jié)構(gòu)的一部分在沒有預兆時可能全部或部分倒塌，這種情況下不可能發(fā)生內(nèi)力重分布，或者說單個構(gòu)件破壞將導致整個結(jié)構(gòu)倒塌；</p>

63、<p>　　用以從其他方面考慮結(jié)構(gòu)達到極限狀態(tài)后的嚴重程度，例如經(jīng)濟后果，對社會的危險性等。</p><p>　　通常將計入或中，因此它并不在設(shè)計計算中直接出現(xiàn)。</p><p>　　極限狀態(tài)設(shè)計法的優(yōu)點是允許對結(jié)構(gòu)的安全性和適用性作出更合理和靈活的估計，對各種有關(guān)的系數(shù)作了統(tǒng)一化處理，在一定程度上可用數(shù)值表示。理想情況是荷載和強度應該由數(shù)理統(tǒng)計方法給出，但實際上這幾乎是不可能的