建筑畢業(yè)設(shè)計(jì)中英對(duì)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(duì)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

2、的建造和改造建筑物的高額費(fèi)用，所以連續(xù)倒塌分析方法是絕對(duì)必要且可信的。對(duì)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。</

3、p><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)

4、鍵組件的損壞。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(duì)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

5、物的高額費(fèi)用，所以連續(xù)倒塌分析方法是絕對(duì)必要且可信的。對(duì)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

6、構(gòu)件造成的不同水平的損壞來對(duì)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

7、法分為兩類，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(duì)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(dòng)力效應(yīng)還

8、有損壞都被包括在這種模擬當(dāng)中。在這個(gè)部分，我們會(huì)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(duì)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(huì)，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

9、括鋼筋混凝土柱，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(dòng)，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)

10、確的重現(xiàn)了在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(duì)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(duì)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?？墒?，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

11、做很多的實(shí)驗(yàn)。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(shí)結(jié)構(gòu)動(dòng)力學(xué)，損傷力學(xué)，動(dòng)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)?/p>

12、世界貿(mào)易中心北塔進(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AUTODY

13、N殼求解器和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(duì)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?？梢钥吹?，建筑高度的一半已經(jīng)倒塌了。

14、計(jì)算結(jié)果表明，對(duì)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(huì)影響到結(jié)果的準(zhǔn)確性，同時(shí)可能會(huì)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(duì)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、gt;<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

16、．DYNA計(jì)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(huì)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

17、基于交替荷載路徑法的DoD指導(dǎo)方針得出的結(jié)果?；诮惶婧奢d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

18、的效率。</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(dòng)力學(xué)、損傷力學(xué)、動(dòng)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(dòng)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

19、爆炸情景。隨著計(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>　　Methods for Progressive Collapse Analysis of Building  Structures Under Blast and Impact Loads</p><

20、;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 collapse of building structures under bla

21、st 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 progressive collapse to blast and impact load

22、s. 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 collapse analysis methods be rel<

23、;/p><p>　　Keywords： progressive collapse analysis；building structures；blast load：impact load</p><p>　　Progressive collapse is defined as“the spread of an initial local failure from element to eleme

24、nt 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 give rise to a more widespread failur

25、e 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</p><p>　　With the rec

26、ent 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 induced by blast and impact loads．

27、</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 of the catastrophic nature of progre

28、ssive 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 engineers，their methodology to carry ou

29、t 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 could be classified into two major cate

30、gories，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 method with analysis of the structure by

31、 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>　　1. Progressive collapse analysi

32、s methods for building structures.</p><p>　　In this section，the current methods for analyzing structural progressive collapse available in the literature are presented in two major categories，namely the dire

33、ct simulation method and the alternative load path method．</p><p>　　1.1 Direct simulation method</p><p>　　For the direct simulation method，the building structures，air，and explosive are all model

34、ed 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 derived and directly applied to structur

35、al 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 typical applications of direct simul

36、ation 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><p>　　Luccioni et al carr

37、ied 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 analysis，the building was modeled using

38、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.</p><p>　　The analysis of

39、 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 the second part consisted of the ana

40、lysis 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 motion generated by the explosion

41、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 of structures．That is，the method co

42、uld 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 material parameters，experiments shou

43、ld 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 World Trade Center</p><p>

44、;　　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 event of impact and collapse of the

45、 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 simulation contained a total of 27

46、0 000 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 stresses and strains from gravity；si

47、mulation 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 collapse of the Tower driven by gravity．

48、</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 collapsed to half of its height．The numeri

49、cal 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 progressive analysis，a reasonable s

50、implification 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 et ai proposed a DYN method based o

51、n 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 not directly modeled．Instead， blast

52、 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 the building structure．</p>&

53、lt;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—defined subroutines was used to perform

54、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 to be 1 000kg equivalent of TNT，wh

55、ile 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 method analysis．As can be seen，DYN m

56、ethod 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 based alternative load path methods．It

57、 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 mentioned above，the great improvement of

58、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．It uses the profound knowledge of bl

59、ast 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 efficiency of the simulation．</p>&l

60、t;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 profound knowledge of structural dynamics，

61、damage mechanics，dynamic material properties and computational skills．It is therefore not practical for common engineering application．The practicability of this category of methods could be improved in the following way