土木專業(yè)畢業(yè)設(shè)計(jì)中英對照外文翻譯--建筑結(jié)構(gòu)在沖擊負(fù)載作用下連續(xù)倒塌分析方法

1、<p>　　建筑結(jié)構(gòu)在沖擊負(fù)載作用下連續(xù)倒塌分析方法</p><p>　　LI Zhongxian(李忠獻(xiàn))，SHI Yanchao(師燕超)</p><p>　　摘要：建筑物在沖擊負(fù)載作用下的連續(xù)倒塌已經(jīng)引起了全世界的極大關(guān)注。對于一個(gè)經(jīng)濟(jì)的，安全的，能夠抵抗沖擊負(fù)載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計(jì)，連續(xù)倒塌分析是必不可少的。因?yàn)檫B續(xù)倒塌的災(zāi)難性特點(diǎn)，和為了抵抗它而潛在的建造和改造

2、建筑物的高額費(fèi)用，所以連續(xù)倒塌分析方法是絕對必要且可信的。對于工程師們而言，他們估算連續(xù)倒塌的方法不僅僅要求精確和簡要，而且容易上手，立竿見影。因而，最近許多研究者都在發(fā)展可靠有效和直接的連續(xù)倒塌分析方法上花費(fèi)了很多的精力。在最近的干物上，當(dāng)前在文獻(xiàn)資料中找得到的關(guān)于連續(xù)倒塌的分析方法被重新審閱。人們廣泛討論它們的適宜性、適用性和可靠性。我們也提出了最近剛剛完成的關(guān)于鋼筋混凝土框架在爆破荷載下的連續(xù)倒塌新分析方法。</p>

3、<p>　　關(guān)鍵詞：連續(xù)倒塌分析；建筑結(jié)構(gòu)；爆炸荷載；沖擊荷載</p><p>　　連續(xù)倒塌被定義為“由于一個(gè)基本的局部構(gòu)件失效在構(gòu)件之間擴(kuò)散最終造成整個(gè)結(jié)構(gòu)或者是不成比例的一大部分倒塌”。其含義為一個(gè)或者一組關(guān)鍵承重構(gòu)件的失效造成周圍構(gòu)件的失效和部分或者是整個(gè)結(jié)構(gòu)的倒塌。建筑結(jié)構(gòu)的連續(xù)倒塌可能由一系列的意外和人為的因素造成，比如：錯(cuò)誤的建造順序，偶然過載造成的局部失效，爆炸和地震造成的關(guān)鍵組件的損壞

4、。這篇論文僅僅研究了特殊荷載（如：爆炸和沖擊），造成的建筑結(jié)構(gòu)連續(xù)倒塌的分析。</p><p>　　隨著最近Alfred P．Murrah聯(lián)邦大樓和世界貿(mào)易中心（WTC）的倒塌，許多的研究更多的關(guān)注如何建造抵抗由于爆炸和沖擊荷載造成連續(xù)倒塌的建筑。對于一個(gè)經(jīng)濟(jì)的，安全的，能夠抵抗沖擊負(fù)載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計(jì)，連續(xù)倒塌分析是必不可少的。因?yàn)檫B續(xù)倒塌的災(zāi)難性特點(diǎn)，和為了抵抗它而潛在的建造和改造建筑物的高額費(fèi)用

5、，所以連續(xù)倒塌分析方法是絕對必要且可信的。對于工程師們而言，他們估算連續(xù)倒塌的方法不僅僅要求精確和簡要，而且容易上手，立竿見影。因而，最近許多研究者都在發(fā)展可靠有效和直接的連續(xù)倒塌分析方法上花費(fèi)了很多的精力。</p><p>　　目前可行的結(jié)構(gòu)連續(xù)倒塌分析方法可以被大致分為兩類：直接模擬法，這種方法直接模擬了使結(jié)構(gòu)破壞和建筑物倒塌的爆炸荷載效應(yīng)，和非耦合交替荷載路徑法，這種方法通過模擬由于移除關(guān)鍵承重構(gòu)件造成的不

6、同水平的損壞來對結(jié)構(gòu)進(jìn)行分析。在最近的干物上，當(dāng)前在文獻(xiàn)資料中找得到的關(guān)于連續(xù)倒塌的分析方法被重新審閱。這些文獻(xiàn)既有優(yōu)點(diǎn)又有不足之處。人們廣泛討論它們的適宜性、適用性和可靠性。我們最近也提出了剛剛完成的關(guān)于鋼筋混凝土框架在爆破荷載下的連續(xù)倒塌新的分析方法。</p><p>　　1、建筑結(jié)構(gòu)連續(xù)倒塌分析方法</p><p>　　在這個(gè)部分，現(xiàn)今在文獻(xiàn)中可以找到的結(jié)構(gòu)連續(xù)倒塌分析方法分為兩類，

7、直接模擬法和交替荷載路徑法。</p><p><b>　　1.1 直接模擬法</b></p><p>　　在直接模擬法中，建筑結(jié)構(gòu)，氣流和爆炸都被細(xì)致的建立到模型中去。對于爆炸產(chǎn)生的沖擊波的傳播方式和其與結(jié)構(gòu)之間的相互作用都需要模擬，或者，需要導(dǎo)出作用在建筑結(jié)構(gòu)上的爆炸和沖擊荷載并使它們直接作用在結(jié)構(gòu)構(gòu)件上。大多數(shù)爆炸和沖擊造成的材料非線性反應(yīng)和動力效應(yīng)還有損壞都被包

8、括在這種模擬當(dāng)中。在這個(gè)部分，我們會列出直接模擬法在建筑結(jié)構(gòu)連續(xù)倒塌分析方法中的幾種典型的應(yīng)用，每種都有各自的特點(diǎn)。</p><p>　　1.1.1 爆炸荷載下的建筑倒塌的直接模擬</p><p>　　Luccioni et al 曾經(jīng)對一座真實(shí)的建筑物進(jìn)行了結(jié)構(gòu)倒塌分析。這座建筑叫做“AMIA”，屬于阿根廷猶太人互濟(jì)會，被恐怖分子襲擊并倒塌。在這項(xiàng)分析當(dāng)中，用3維固體構(gòu)件（包括鋼筋混凝土

9、柱，梁和砌體墻）組裝成這座建筑物的模型。圖1表現(xiàn)了這座建筑物的結(jié)構(gòu)和爆炸位置。</p><p>　　這座建筑的結(jié)構(gòu)倒塌分析分為兩個(gè)階段。分析的第一個(gè)階段，包括模擬即時(shí)引爆的爆炸本身。第二階段包括建筑與爆炸產(chǎn)生的沖擊波之間的效應(yīng)和相互作用。分析考慮了沖擊波激起的氣流產(chǎn)生的唯一的荷載。爆炸所產(chǎn)生的地面運(yùn)動，沒有考慮。倒塌的建筑物的數(shù)值結(jié)果如圖2所示。數(shù)值結(jié)果和恐怖襲擊之后拍攝的照片比較可以看出：數(shù)值分析準(zhǔn)確的重現(xiàn)了在

10、爆炸荷載作用下建筑的倒塌過程。實(shí)際損壞和數(shù)值模擬的結(jié)果的很好的一致性，證明了細(xì)致化的結(jié)構(gòu)、材料和爆炸效應(yīng)模擬對于這種分析是必需的，并且是現(xiàn)今唯一能夠成功的進(jìn)行的對整個(gè)建筑的完整倒塌分析的方式。</p><p>　　這是利用直接模擬方法分析結(jié)構(gòu)連續(xù)倒塌的一個(gè)很好的例子。這種方法能夠成功的預(yù)測由于爆炸和沖擊荷載造成的連續(xù)倒塌的過程。可是，要達(dá)到這種準(zhǔn)確度是要花費(fèi)很大的代價(jià)的。為了導(dǎo)出準(zhǔn)確的材料參數(shù)，需要先做很多的實(shí)驗(yàn)

11、。建筑結(jié)構(gòu)、空氣和爆炸都需要細(xì)致的建模，這樣就需要成千上萬的基本單元。特定的算法和軟件也同樣需要用來計(jì)算“沖擊波—結(jié)構(gòu)”相互作用，同時(shí)得到結(jié)構(gòu)的損壞和倒塌特性。因此，這是非常費(fèi)時(shí)，而且需要有淵博知識結(jié)構(gòu)動力學(xué)，損傷力學(xué)，動態(tài)材料性能和計(jì)算技能。</p><p>　　1.1.2 世界貿(mào)易中心倒塌分析</p><p>　　Quan和Brinbaum用AUT0DYN 3D計(jì)算機(jī)程序?qū)κ澜缳Q(mào)易中心

12、北塔進(jìn)行了沖擊和倒塌的計(jì)算機(jī)三維模擬，用數(shù)值的方式重現(xiàn)了9月11日世界貿(mào)易中心北塔整個(gè)受沖擊和倒塌的過程。</p><p>　　他們的模型包括整個(gè)世界貿(mào)易中心北塔的建筑和波音767客機(jī)。模擬中運(yùn)用的三維有限單元模型包括了總共270 000根梁和殼單元。所有圍墻上以及中央核心中的柱都被簡化，以梁單元來模擬，而非使用固體元素或殼單元。樓板和屋頂用AUTODYN殼求解器來建模。波音767客機(jī)也用AUTODYN殼求解器和

13、拉格朗日求解器來建模。圖3是AUTODYN產(chǎn)生的世界貿(mào)易中心北塔和波音767客機(jī)三維有限單元模型。</p><p>　　完整的模擬包括四個(gè)部分：靜力平衡計(jì)算得到初步壓力和重力引起的應(yīng)變;對波音767客機(jī)撞擊北塔的模擬；撞擊泄漏的燃料燃燒造成的北塔強(qiáng)度和剛度的衰減；最后，重力作用引起的北塔連續(xù)倒塌。圖4給出了一個(gè)典型的結(jié)果，它表示了材料在塔遭受撞擊之后6.5秒的位置。可以看到，建筑高度的一半已經(jīng)倒塌了。計(jì)算結(jié)果表明

14、，對北塔遭受撞擊和倒塌的科學(xué)合理的、真實(shí)的、可行的方案可以通過數(shù)值模擬得到。在連續(xù)性分析中，一個(gè)在建模過程中合理的簡化，比如用簡單的單元來代表復(fù)雜的結(jié)構(gòu)構(gòu)件性能，不會影響到結(jié)果的準(zhǔn)確性，同時(shí)可能會顯著的減少模型大小。這樣能夠節(jié)省大量的計(jì)算內(nèi)存和計(jì)算時(shí)間，特別是對復(fù)雜的結(jié)構(gòu)，如高層建筑。當(dāng)然，特定的有限的單元仍然需要形成。</p><p>　　1.1.3 DYN法分析鋼筋混凝土框架連續(xù)倒塌</p>&

15、lt;p>　　Hao et ai提出了基于連續(xù)損傷力學(xué)理論的DYN方法。這種方法與其他直接模擬方法的主要區(qū)別是爆炸的初值和沖擊波的傳播不是直接建模的。取而代之的是，作用在結(jié)構(gòu)上的沖擊荷載是首先用TM5-1300和Ref.中給出的公式計(jì)算出，然后它們被直接作用于建筑結(jié)構(gòu)的正面、側(cè)面、屋頂和背面。</p><p>　　這個(gè)方法被用來分析三層兩跨的鋼筋混凝土框架結(jié)構(gòu)。分析利用的是用戶自定義副程式的LS．DYNA計(jì)

16、算機(jī)程序。圖5給出了鋼筋混凝土結(jié)構(gòu)的布置和爆炸位置。在這個(gè)分析當(dāng)中，爆炸被假定在地表引發(fā)。這次爆炸相當(dāng)于1000公斤TNT當(dāng)量，換算距離為1.7m/kg,這樣只有第一層的中柱會由于爆炸的影響而倒塌。</p><p>　　圖6中顯示了DYN分析方法得到的結(jié)構(gòu)連續(xù)倒塌的數(shù)值結(jié)果。從中可以看出，DYN方法給出了合理的鋼筋混凝土框架在臨界沖擊荷載作用下倒塌預(yù)測值。在他們的研究中，同樣比較了DYN方法、GSA和基于交替荷載

17、路徑法的DoD指導(dǎo)方針得出的結(jié)果。基于交替荷載路徑法的GSA和DoD被發(fā)現(xiàn)可能給不出可靠的結(jié)構(gòu)連續(xù)倒塌預(yù)測并且常常低估爆炸破壞的柱子頂部支撐節(jié)點(diǎn)的應(yīng)力和應(yīng)變。</p><p>　　上面提到DYN方法最為巨大的改進(jìn)是沖擊波和建筑結(jié)構(gòu)之間的相互作用，最初的爆炸和沖擊波傳播并不需要直接模擬。它運(yùn)用深厚的爆炸荷載分布理論來定義爆炸荷載然后把它們直接作用在結(jié)構(gòu)上。這能夠可觀的減少有限單元模型的尺寸，同時(shí)增加模擬的效率。&l

18、t;/p><p>　　總得來說，直接模擬法能夠產(chǎn)生可信的結(jié)構(gòu)在爆炸和沖擊荷載作用下倒塌的預(yù)測結(jié)果，但是那是以大量的時(shí)間投入，淵博的結(jié)構(gòu)動力學(xué)、損傷力學(xué)、動態(tài)材料特性和計(jì)算技巧為基礎(chǔ)的。因此，它不適用于實(shí)際工程應(yīng)用。這類方法的可行性可以按照以下的方法進(jìn)行改：1）開發(fā)新的有限單元，不僅僅要易于建立和計(jì)算，并且能夠描述復(fù)雜的結(jié)構(gòu)構(gòu)件特性，如非線性和動力特性；2）提出新的方法，準(zhǔn)確預(yù)測負(fù)荷爆炸周圍建筑結(jié)構(gòu)的不同的爆炸情景。隨

19、著計(jì)算機(jī)科學(xué)的發(fā)展，與改善有限元模型和荷載運(yùn)用方法的進(jìn)步，直接模擬方法有可能成為進(jìn)行爆炸和沖擊荷載作用下結(jié)構(gòu)連續(xù)倒塌分析的一種準(zhǔn)確有效的方法。</p><p><b>　　原文出處：</b></p><p>　　Methods for Progressive Collapse Analysis of Building  Structures Under Bl

20、ast and Impact Loads</p><p>　　LI Zhongxian(李忠獻(xiàn))，SHI Yanchao(師燕超)</p><p>　　(School of Civil Engineering，Tianjin University，Tianjin 300072，China)</p><p>　　Abstract： Progressive collap

21、se of building structures under blast and impact loads has attracted great attention all over the world．Progressive collapse analysis is essential for an economic and safe design of building structures against progressiv

22、e collapse to blast and impact loads. Because of the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it，it is imperative that the progressive

23、collapse analysis methods be rel</p><p>　　Keywords： progressive collapse analysis；building structures；blast load：impact load</p><p>　　Progressive collapse is defined as“the spread of an initial

24、local failure from element to element resulting in the collapse of an entire structure or a disproportionately large part of it”. It refers to the failure of one or a group of key structural load—carrying members that gi

25、ve rise to a more widespread failure of the surrounding members and partial or complete structural collapse．Progressive collapse of building structures might be induced by a series of accidental and intentional events su

26、</p><p>　　With the recent progressive collapse of Alfred P．Murrah Federal Building and world Trade Center (WTC))researches are more focused than ever on constructing buildings safer from progressive collapse

27、 induced by blast and impact loads．</p><p>　　Progressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loads．Because o

28、f the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it，it is imperative that the progressive collapse analysis methods be reliable． For engi

29、neers，their methodology to carry out progressive collapse uation need not only to be accurate and concise，but also be </p><p>　　The current available methods in analyzing structural progressive collapse coul

30、d be classified into two major categories，namely the direct simulation method，in which the blast loading effects on structural damage and building collapse are directly simulated，and uncoupled alternative load path metho

31、d with analysis of the structure by simulating various levels of damage by the removal of key load—carrying members．In the present paper，the available progressive collapse analysis methods in the liter</p><p&g

32、t;　　1. Progressive collapse analysis methods for building structures.</p><p>　　In this section，the current methods for analyzing structural progressive collapse available in the literature are presented in t

33、wo major categories，namely the direct simulation method and the alternative load path method．</p><p>　　1.1 Direct simulation method</p><p>　　For the direct simulation method，the building structu

34、res，air，and explosive are all modeled in detail．Explosion，blast wave propagation and its interaction with structures all need to be simulated，if not，blast and impact loads acting on the building structure should be deriv

35、ed and directly applied to structural components．</p><p>　　The material nonlinear behavior and dynamic effects and damage due to blast or impact are mostly included in the simulation．This section will list t

36、ypical applications of direct simulation method in progressive collapse analysis of building structures recently，each with its own characteristic.</p><p>　　1.1.1 of building collapse under blast loads</p&

37、gt;<p>　　Luccioni et al carried out an analysis of structural collapse of an actual building，the AMIA (Israel’s Mutual Society of Argentina)building，which had suffered a terrorist attack and collapsed．In the analy

38、sis，the building was modeled using 3一dimensional solid elements， including the reinforced concrete columns，beams and masonry walls．Fig．1 gives the configuration of the building model and the location of the explosion.<

39、;/p><p>　　The analysis of the structural collapse of the building was performed in two stages．The first part of the analysis consisted of the simulation of the explosion itself from the detonation instant and t

40、he second part consisted of the analysis of the effect and interaction with the building of the blast wave generated by the explosion．Only the load produced by the air blast wave was considered in the analysis．The ground

41、 motion generated by the explosion was not taken into account． ig．2 shows the nu</p><p>　　This case represents a good example of using direct simulation method to carry out the progressive collapse analysis

42、of structures．That is，the method could successfully predict the progressive collapse process of the structure under blast and impact loads．However，this accuracy is achieved at great cost．In order to derive the accurate m

43、aterial parameters，experiments should be carried out first．The building structures，air，and，explosive should be modeled in detail，which need thousands of elements．S</p><p>　　1．1．2 Collapse analysis of the Wor

44、ld Trade Center</p><p>　　Quan and Brinbaum carried out a 3-dimensiona1 computer simulation of impact and collapse of the WTC North Tower using AUT0DYN 3D computer program to numerically reproduce the entire

45、event of impact and collapse of the North Tower of WTC on September l1.Their model included the entire building of the WTC North Tower and a Boeing 767 passenger jet．The three—dimensional finite element model used in the

46、 simulation contained a total of 270 000 beam and shell elements．All the columns on the perimeter </p><p>　　The complete simulation consists of four stages：static equilibrium calculation to get the initial s

47、tresses and strains from gravity；simulation of a Boeing 767 airplane impacting the tower；the reduction of the strength and stiffness of the tower resulting from the post-impact fuel fire；and finally，the progressive colla

48、pse of the Tower driven by gravity．</p><p>　　Fig．4 gives one of the typical results，which presents the material location of the tower at 6．5 s after the impact．As can be seen，the building had already collaps

49、ed to half of its height．The numerical results showed that a scientifically substantiated plausible scenario for the impact and collapse event of the North Tower could be obtained through the numerical simulation．In the

50、progressive analysis，a reasonable simplification in the modeling such as using simple elements to represent complex be</p><p>　　1.1.3 DYN method in progressive analysis of RC flame</p><p>　　Hao

51、et ai proposed a DYN method based on the continuum damage mechanics theory．The main difference between this method and other direct simulation methods is that the explosion initialization and blast wave propagation were

52、not directly modeled．Instead， blast loads acting on the structure were calculated first</p><p>　　using the formulae given in TM5—1300 and Ref.． Then they are directly applied on front，side，roof and rear of t

53、he building structure．</p><p>　　This method was used to analyze structural progressive collapse of a three-storey and two-span reinforced concrete（RC）frame structure．Computer software LS．DYNA with user—defin

54、ed subroutines was used to perform the analyses．Fig．5 gives the configuration of the RC frame and the explosive location．In the analysis，the blast was assumed to be detonated on ground surface．The blast weight was chosen

55、 to be 1 000kg equivalent of TNT，while the scaled distance used was 1．7 m／kg ，at which only the first flo</p><p>　　Fig．6 shows the numerical results of the structural progressive collapse obtained from DYN m

56、ethod analysis．As can be seen，DYN method gives reasonable prediction of the RC frame collapse under critical blast load．In their study，comparisons were also made between results from DYN method，GSA and DoD guidelines bas

57、ed alternative load path methods．It was found both the GSA and DoD based alternative load path methods may not give reliable prediction of structural progressive collapse and usually under</p><p>　　As mentio

58、ned above，the great improvement of the DYN method is that，interaction between the blast wave and building structure，blast initial and blast wave</p><p>　　propagation are not needed to be directly simulated．I

59、t uses the profound knowledge of blast load distribution to define the blast loads and then directly apply them to the structure．This could dramatically decrease the size of finite element model and increase the efficien

60、cy of the simulation．</p><p>　　To sum up，the direct simulation method can yield reliable predictions of structural collapse to blast and impact loads，but it is extremely time consuming，and requires a profoun

61、d knowledge of structural dynamics，damage mechanics，dynamic material properties and computational skills．It is therefore not practical for common engineering application．The practicability of this category of methods cou