畢業(yè)設(shè)計中英對照翻譯

1、建筑結(jié)構(gòu)在沖擊負載作用下連續(xù)倒塌分析方法          LI Zhongxian(李忠獻)，SHI Yanchao(師燕超) 摘要：建筑物在沖擊負載作用下的連續(xù)倒塌已經(jīng)引起了全世界的極大關(guān)注。對于一個經(jīng)濟的，安全的，能夠抵抗沖擊負載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計，連續(xù)倒塌分析是必不可少的。因為連續(xù)倒塌的災(zāi)難性特點，和為了抵抗它而潛在的建造和改造建筑物的高額費用，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

2、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了很多的精力。在最近的干物上，當前在文獻資料中找得到的關(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。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    連續(xù)倒塌被定義為“由于一個基本的局部構(gòu)件失效在構(gòu)件之間擴散最終造成整個結(jié)構(gòu)或者是不成比例的一大部分倒塌”。其含義為一個或者一組關(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

3、如：錯誤的建造順序，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。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。     隨著最近Alfred PMurrah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。對于一個經(jīng)濟的，安全的，能夠抵抗沖擊負載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計，連續(xù)倒塌分析是必不可少的。因為連續(xù)倒塌的災(zāi)難性特點，和為了抵抗它而潛在的建造和改造建筑物的高額費用，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

4、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了很多的精力。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)件造成的不同水平的損壞來對結(jié)構(gòu)進行分析。在最近的干物上，當前在文獻資料中找得到的關(guān)于連續(xù)倒塌的分析方法被重新審閱。這些文獻既有優(yōu)點又有不足之處。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。1、建筑結(jié)構(gòu)連續(xù)倒塌分析方法

5、60;  在這個部分，現(xiàn)今在文獻中可以找到的結(jié)構(gòu)連續(xù)倒塌分析方法分為兩類，直接模擬法和交替荷載路徑法。1.1 直接模擬法    在直接模擬法中，建筑結(jié)構(gòu)，氣流和爆炸都被細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)還有損壞都被包括在這種模擬當中。在這個部分，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。 爆炸荷載下的建筑倒塌的直接模擬 

6、0;  Luccioni et al 曾經(jīng)對一座真實的建筑物進行了結(jié)構(gòu)倒塌分析。這座建筑叫做“AMIA”，屬于阿根廷猶太人互濟會，被恐怖分子襲擊并倒塌。在這項分析當中，用3維固體構(gòu)件（包括鋼筋混凝土柱，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。                     這座建筑的結(jié)構(gòu)倒塌分析分為兩個階段。分析的第一個階段，包括模擬即時引爆的爆炸本身。

7、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)值分析準確的重現(xiàn)了在爆炸荷載作用下建筑的倒塌過程。實際損壞和數(shù)值模擬的結(jié)果的很好的一致性，證明了細致化的結(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行的對整個建筑的完整倒塌分析的方式。               &#

8、160;  這是利用直接模擬方法分析結(jié)構(gòu)連續(xù)倒塌的一個很好的例子。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?，要達到這種準確度是要花費很大的代價的。為了導(dǎo)出準確的材料參數(shù)，需要先做很多的實驗。建筑結(jié)構(gòu)、空氣和爆炸都需要細致的建模，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算“沖擊波結(jié)構(gòu)”相互作用，同時得到結(jié)構(gòu)的損壞和倒塌特性。因此，這是非常費時，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)材料性能和計算技能。 世界貿(mào)易中心倒塌分析    Quan和Brinbaum用AUT0DYN 3D計算機程序?qū)κ澜缳Q(mào)易中心北

9、塔進行了沖擊和倒塌的計算機三維模擬，用數(shù)值的方式重現(xiàn)了9月11日世界貿(mào)易中心北塔整個受沖擊和倒塌的過程。他們的模型包括整個世界貿(mào)易中心北塔的建筑和波音767客機。模擬中運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客機也用AUTODYN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客機三維有限單元模型。         &

10、#160;          完整的模擬包括四個部分：靜力平衡計算得到初步壓力和重力引起的應(yīng)變;對波音767客機撞擊北塔的模擬；撞擊泄漏的燃料燃燒造成的北塔強度和剛度的衰減；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。計算結(jié)果表明，對北塔遭受撞擊和倒塌的科學(xué)合理的、真實的、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)果的準確性，同時可能

11、會顯著的減少模型大小。這樣能夠節(jié)省大量的計算內(nèi)存和計算時間，特別是對復(fù)雜的結(jié)構(gòu)，如高層建筑。當然，特定的有限的單元仍然需要形成。                DYN法分析鋼筋混凝土框架連續(xù)倒塌    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

12、計算出，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。這個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LSDYNA計算機程序。圖5給出了鋼筋混凝土結(jié)構(gòu)的布置和爆炸位置。在這個分析當中，爆炸被假定在地表引發(fā)。這次爆炸相當于1000公斤TNT當量，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。                    

13、0;        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)點的應(yīng)力和應(yīng)變。              

14、;   上面提到DYN方法最為巨大的改進是沖擊波和建筑結(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，同時增加模擬的效率。    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)材料特性和計算技巧為基礎(chǔ)的。因此，它不適用于實際工程應(yīng)用。這類方法的可行性可以按照以下的方法進行改：1）開發(fā)新的有限單元，不僅僅要易于建立和計算，并且能夠描述復(fù)雜的結(jié)構(gòu)

15、構(gòu)件特性，如非線性和動力特性；2）提出新的方法，準確預(yù)測負荷爆炸周圍建筑結(jié)構(gòu)的不同的爆炸情景。隨著計算機科學(xué)的發(fā)展，與改善有限元模型和荷載運用方法的進步，直接模擬方法有可能成為進行爆炸和沖擊荷載作用下結(jié)構(gòu)連續(xù)倒塌分析的一種準確有效的方法。   Methods for Progressive Collapse Analysis of Building  Structures Under Blast and Impact Loads           

16、60;                               LI Zhongxian(李忠獻)，SHI Yanchao(師燕超)(School of Civil Engineering，Tianjin University，Tianjin 300072，China)Abstract： Pro

17、gressive collapse of building structures under blast and impact loads has attracted great attention all over the worldProgressive 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

18、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 engineers their methodology to carry out progressive collapse uation need not only be accurate and conc

19、ise，but also be easily used and works fastThus，many researchers have been spending lots of effort in developing reliable，efficient and straightforward progressive collapse analysis methods recently. In the present paper，current progressive collapse analysis methods available in the literature are re

20、viewedTheir suitability applicability and reliability are discussedOur recent proposed new method for progressive collapse analysis of reinforced concrete frames under blast loads is also introducedKeywords： progressive collapse analysis；building structures；blast load：impact load    P

21、rogressive collapse is defined as“the spread of an initial 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 loadcarrying members that give rise to a more wide

22、spread failure of the surrounding members and partial or complete structural collapseProgressive collapse of building structures might be induced by a series of accidental and intentional events such as false construction order，local failure due to accidental overload，damage of critical component by

23、 explosion and earthquakeThis paper only focuses on progressive collapse analysis of building structures induced by abnormal loads，such as blast and impact    With the recent progressive collapse of Alfred PMurrah Federal Building and world Trade Center (WTC)researches are more focuse

24、d than ever on constructing buildings safer from progressive collapse induced by blast and impact loadsProgressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loadsBecause of the catastrophic nature of progres

25、sive 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 out progressive collapse uation need not only to be accurate and concise，but also be

26、 easily used and works fastThus，many researchers have been spending lots of effort in developing reliable，efficient and straightforward progressive collapse analysis methods recently    The current available methods in analyzing structural progressive collapse could be classified into

27、 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 method with analysis of the structure by simulating various levels of damage by the removal of key loadca

28、rrying membersIn the present paper，the available progressive collapse analysis methods in the literature are reviewed according to their categoriesBoth advantages and disadvantages of each method are listedTheir suitability，applicability and reliability are also discussedOur recently proposed new me

29、thod for progressive collapse analysis of reinforced concrete frames under blast 1oads is al so introduced1. Progressive collapse analysis methods for building structures.    In this section，the current methods for analyzing structural progressive collapse available in the literature

30、are presented in two major categories，namely the direct simulation method and the alternative load path method1.1 Direct simulation method    For the direct simulation method，the building structures，air，and explosive are all modeled in detailExplosion，blast wave propagation and its in

31、teraction 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 structural componentsThe material nonlinear behavior and dynamic effects and damage due to blast or impact are mostly included in the simulation

32、This section will list typical applications of direct simulation method in progressive collapse analysis of building structures recently，each with its own characteristic. of building collapse under blast loads    Luccioni et al carried out an analysis of structural collapse of an actu

33、al building，the AMIA (Israels Mutual Society of Argentina)building，which had suffered a terrorist attack and collapsedIn the analysis，the building was modeled using 3一dimensional solid elements， including the reinforced concrete columns，beams and masonry wallsFig1 gives the configuration of the buil

34、ding model and the location of the explosion.                The analysis of the structural collapse of the building was performed in two stagesThe first part of the analysis consisted of the simulation of the explosion itsel

35、f from the detonation instant and the second part consisted of the analysis of the effect and interaction with the building of the blast wave generated by the explosionOnly the load produced by the air blast wave was considered in the analysisThe ground motion generated by the explosion was not take

36、n into account ig2 shows the numerical results of the collapsed buildingThe comparison of numerical results with photographs taken after the terrorist attack showed that the numerical analysis accurately reproduced the collapse of the building under the blast loadThe good agreement between actual da

37、mage and that one numerically obtained proves that the detailed simulation of the structure，materials and blast effects are needed for this type of analysis and nowadays represent the only way to successfully run a complete collapse analysis of an entire building      &

38、#160;          This case represents a good example of using direct simulation method to carry out the progressive collapse analysis of structuresThat is，the method could successfully predict the progressive collapse process of the structure under blast and imp

39、act loadsHowever，this accuracy is achieved at great costIn order to derive the accurate material parameters，experiments should be carried out firstThe building structures，air，and，explosive should be modeled in detail，which need thousands of elementsSpecial algorithms and software were also needed to

40、 calculate the blast wave-structure interaction and to catch the damage and collapse behavior of the building structureTherefore，it is extremely time consuming，and requires a profound knowledge of structural dynamics，damage mechanics，dynamic material properties and computational skills112 Collapse a

41、nalysis of the World Trade Center    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 North Tower of WTC on Sep

42、tember l1.Their model included the entire building of the WTC North Tower and a Boeing 767 passenger jetThe threedimensional finite element model used in the simulation contained a total of 270 000 beam and shell elementsAll the columns on the perimeter wall as well as inside the central core were s

43、implified，being modeled by beam elements instead of using solid elements or shell elementsFloors and roof were modeled by the AUTODYN shell solverThe Boeing 767 airplane was also modeled in detail using AUTODYN shell solver and Lagrange solverFig3 gives the AUTODYN-generated 3一dimensional finite ele

44、ment model of the WTC North Tower and the Boeing 767 airplane                 The complete simulation consists of four stages：static equilibrium calculation to get the initial stresses and strains from gravity；simulation of a Boei

45、ng 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 gravityFig4 gives one of the typical results，which presents the material location of the tower at 65 s aft

46、er the impactAs can be seen，the building had already collapsed to half of its heightThe 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 simulationIn the progressive analysis，a

47、 reasonable simplification in the modeling such as using simple elements to represent complex behavior of structural members will not affect the accuracy of the results，while this might dramatically reduce the size of the mode1This could save lots of computer memories and computing time，especially f

48、or the complex structures，such as tall buildingsOf course， certain finite elements are still needed to be developed             DYN method in progressive analysis of RC flame    Hao et ai proposed a DYN method based on the co

49、ntinuum damage mechanics theoryThe main difference between this method and other direct simulation methods is that the explosion initialization and blast wave propagation were not directly modeledInstead， blast loads acting on the structure were calculated firstusing the formulae given in TM51300 an

50、d Ref. Then they are directly applied on front，side，roof and rear of the building structure    This method was used to analyze structural progressive collapse of a three-storey and two-span reinforced concrete（RC）frame structureComputer software LSDYNA with userdefined subroutines was

51、 used to perform the analysesFig5 gives the configuration of the RC frame and the explosive locationIn the analysis，the blast was assumed to be detonated on ground surfaceThe blast weight was chosen to be 1 000kg equivalent of TNT，while the scaled distance used was 17 mkg ，at which only the first fl

52、oor middle column would collapse due to blast effects                       Fig6 shows the numerical results of the structural progressive collapse obtained from DYN method analysisAs can be seen

53、，DYN method gives reasonable prediction of the RC frame collapse under critical blast loadIn their study，comparisons were also made between results from DYN method，GSA and DoD guidelines based alternative load path methodsIt was found both the GSA and DoD based alternative load path methods may not give reliable prediction of st