外文翻譯---使用高級(jí)分析法的鋼框架創(chuàng)新設(shè)計(jì)

1、<p>　　使用高級(jí)分析法的鋼框架創(chuàng)新設(shè)計(jì)</p><p><b>　　1．導(dǎo)言</b></p><p>　　在美國(guó)，鋼結(jié)構(gòu)設(shè)計(jì)方法包括允許應(yīng)力設(shè)計(jì)法(ASD)，塑性設(shè)計(jì)法(PD)和荷載阻力系數(shù)設(shè)計(jì)法(LRFD)。在允許應(yīng)力設(shè)計(jì)中，應(yīng)力計(jì)算基于一階彈性分析，而幾何非線性影響則隱含在細(xì)部設(shè)計(jì)方程中。在塑性設(shè)計(jì)中，結(jié)構(gòu)分析中使用的是一階塑性鉸分析。塑性設(shè)計(jì)使整個(gè)

2、結(jié)構(gòu)體系的彈性力重新分配。盡管幾何非線性和逐步高產(chǎn)效應(yīng)并不在塑性設(shè)計(jì)之中，但它們近似細(xì)部設(shè)計(jì)方程。在荷載和阻力系數(shù)設(shè)計(jì)中，含放大系數(shù)的一階彈性分析或單純的二階彈性分析被用于幾何非線性分析，而梁柱的極限強(qiáng)度隱藏在互動(dòng)設(shè)計(jì)方程。所有三個(gè)設(shè)計(jì)方法需要獨(dú)立進(jìn)行檢查，包括系數(shù)K計(jì)算。在下面，對(duì)荷載抗力系數(shù)設(shè)計(jì)法的特點(diǎn)進(jìn)行了簡(jiǎn)要介紹。</p><p>　　結(jié)構(gòu)系統(tǒng)內(nèi)的內(nèi)力及穩(wěn)定性和它的構(gòu)件是相關(guān)的，但目前美國(guó)鋼結(jié)構(gòu)協(xié)會(huì)（AI

3、SC）的荷載抗力系數(shù)規(guī)范把這種分開來處理的。在目前的實(shí)際應(yīng)用中，結(jié)構(gòu)體系和它構(gòu)件的相互影響反映在有效長(zhǎng)度這一因素上。這一點(diǎn)在社會(huì)科學(xué)研究技術(shù)備忘錄第五錄摘錄中有描述。</p><p>　　盡管結(jié)構(gòu)最大內(nèi)力和構(gòu)件最大內(nèi)力是相互依存的（但不一定共存），應(yīng)當(dāng)承認(rèn)，嚴(yán)格考慮這種相互依存關(guān)系，很多結(jié)構(gòu)是不實(shí)際的。與此同時(shí)，眾所周知當(dāng)遇到復(fù)雜框架設(shè)計(jì)中試圖在柱設(shè)計(jì)時(shí)自動(dòng)彌補(bǔ)整個(gè)結(jié)構(gòu)的不穩(wěn)定（例如通過調(diào)整柱的有效長(zhǎng)度）是很困難

4、的。因此，社會(huì)科學(xué)研究委員會(huì)建議在實(shí)際設(shè)計(jì)中，這兩方面應(yīng)單獨(dú)考慮單獨(dú)構(gòu)件的穩(wěn)定性和結(jié)構(gòu)的基礎(chǔ)及結(jié)構(gòu)整體穩(wěn)定性。圖28.1就是這種方法的間接分析和設(shè)計(jì)方法。</p><p>　　在目前的美國(guó)鋼結(jié)構(gòu)協(xié)會(huì)荷載抗力系數(shù)規(guī)范中，分析結(jié)構(gòu)體系的方法是一階彈性分析或二階彈性分析。在使用一階彈性分析時(shí)，考慮到二階效果，一階力矩都是由B1,B2系數(shù)放大。在規(guī)范中，所有細(xì)部都是從結(jié)構(gòu)體系中獨(dú)立出來，他們通過細(xì)部?jī)?nèi)力曲線和規(guī)范給出的那

5、些隱含二階效應(yīng)，非彈性，殘余應(yīng)力和撓度的相互作用設(shè)計(jì)的。理論解答和實(shí)驗(yàn)性數(shù)據(jù)的擬合曲線得到了柱曲線和梁曲線，同時(shí)Kanchanalai發(fā)現(xiàn)的所謂“精確”塑性區(qū)解決方案的擬合曲線確定了梁柱相互作用方程。</p><p>　　為了證明單個(gè)細(xì)部?jī)?nèi)力對(duì)整個(gè)結(jié)構(gòu)體系的影響，使用了有效長(zhǎng)度系數(shù)，如圖28.2所示。有效長(zhǎng)度方法為框架結(jié)構(gòu)提供了一個(gè)良好的設(shè)計(jì)。然而，有效長(zhǎng)度方法的使用存在著一些困難，如下所述：</p>

6、<p>　　1、有效長(zhǎng)度的方法不能準(zhǔn)確核算的結(jié)構(gòu)系統(tǒng)及其細(xì)部之間的互相影響。這是因?yàn)樵谝粋€(gè)大的結(jié)構(gòu)體系中的相互作用太復(fù)雜不能簡(jiǎn)單地用有效長(zhǎng)度系數(shù)K代表。因此，這種方法不能準(zhǔn)確地測(cè)算框架單元實(shí)際需要的強(qiáng)度。</p><p>　　2、有效長(zhǎng)度的方法無法獲取結(jié)構(gòu)體系中內(nèi)力非彈性再分配，因?yàn)閹в蠦1、B2系數(shù)的一階彈性分析只證明二階影響，但不是非彈性內(nèi)力再分配。有效長(zhǎng)度的方法只是保守的估計(jì)了最終承載大型結(jié)構(gòu)

7、體系的能力。</p><p>　　3、有效長(zhǎng)度方法無法測(cè)算的結(jié)構(gòu)體系受負(fù)荷載下的失效模式。這是因?yàn)楹奢d抗力系數(shù)相互作用方程不提供在任何負(fù)載下結(jié)構(gòu)體系的失效模式的信息。</p><p>　　4、有效長(zhǎng)度的方法與計(jì)算機(jī)程序不兼容。</p><p>　　5、有效長(zhǎng)度的方法在涉及系數(shù)K的單獨(dú)構(gòu)件能力檢測(cè)時(shí)需要耗費(fèi)比較長(zhǎng)的時(shí)間。</p><p>　　隨

8、著電腦技術(shù)的發(fā)展，細(xì)部結(jié)構(gòu)的穩(wěn)定性和整體結(jié)構(gòu)的穩(wěn)定性這兩個(gè)方面，可以通過結(jié)構(gòu)的最大強(qiáng)度測(cè)定來被嚴(yán)格對(duì)待。圖28.1就是這種方法的間接分析和設(shè)計(jì)方法。直接設(shè)計(jì)方法的發(fā)展被稱為高級(jí)分析，或者更具體地說，二階彈性分析框架設(shè)計(jì)。用這種直接的方式，無須計(jì)算有效長(zhǎng)度系數(shù)，因?yàn)椴恍枰?guī)范方程包含的單獨(dú)構(gòu)件能力檢測(cè)。憑借目前現(xiàn)有的計(jì)算技術(shù)，直接使用高級(jí)分析法技術(shù)框架設(shè)計(jì)是可行的。這種方法過去在辦公室設(shè)計(jì)使用時(shí)一直被認(rèn)為是不切實(shí)際的。本章的目的是提出一個(gè)

9、切實(shí)可行的，直接的鋼框架設(shè)計(jì)方法，使用高級(jí)分析法產(chǎn)生跟荷載抗力系數(shù)法的相同的結(jié)果。</p><p>　　利用高級(jí)設(shè)計(jì)分析的優(yōu)點(diǎn)概述如下：</p><p>　　1、高級(jí)分析法是結(jié)構(gòu)工程師進(jìn)行鋼結(jié)構(gòu)設(shè)計(jì)的另一個(gè)工具，它的通過不是強(qiáng)制性的，而是為設(shè)計(jì)人員提供靈活的選擇。</p><p>　　2、高級(jí)分析法直接獲取了整個(gè)結(jié)構(gòu)體系和細(xì)部結(jié)構(gòu)極限狀態(tài)的強(qiáng)度和穩(wěn)定性，這樣就不需要

10、規(guī)范方程包含的單獨(dú)構(gòu)件能力檢測(cè)。</p><p>　　3、相比荷載阻力系數(shù)設(shè)計(jì)法和允許應(yīng)力設(shè)計(jì)法，高級(jí)分析法通過直接彈性二階分析提供了更多結(jié)構(gòu)性能的信息。</p><p>　　4、高級(jí)分析法解決了常規(guī)荷載阻力系數(shù)設(shè)計(jì)法中由于不兼容彈性全球分析和單元極限狀態(tài)設(shè)計(jì)的困難。</p><p>　　5、高級(jí)分析法與計(jì)算機(jī)程序兼容性良好，但荷載阻力系數(shù)設(shè)計(jì)法和允許應(yīng)力設(shè)計(jì)法則無

11、法與計(jì)算機(jī)程序兼容，因?yàn)樗鼈冊(cè)谶^程中都需要有對(duì)系數(shù)K的單獨(dú)構(gòu)件能力檢測(cè)的計(jì)算。</p><p>　　6、高級(jí)分析法可以得到整個(gè)結(jié)構(gòu)體系彈性內(nèi)力再分配的結(jié)果，并且節(jié)約高度不確定的鋼框架的材料。</p><p>　　7、過去在設(shè)計(jì)室使用高級(jí)分析法被認(rèn)為不切實(shí)際，而現(xiàn)在則是可行的，因?yàn)閭€(gè)人電腦和工程工作站的能力正在迅速提高。</p><p>　　8、通過高級(jí)分析法測(cè)定的各

12、項(xiàng)數(shù)據(jù)都接近了荷載抗力系數(shù)法測(cè)定的那些數(shù)據(jù)，因?yàn)楦呒?jí)分析法對(duì)荷載抗力系數(shù)法的柱曲線和梁柱的相互作用方程進(jìn)行了校準(zhǔn)。因此，高級(jí)分析法替代了荷載抗力系數(shù)法。</p><p>　　9、高級(jí)分析法比較高效，因?yàn)樗耆私?jīng)常引起混淆的冗長(zhǎng)的單獨(dú)構(gòu)件能力檢測(cè)，包括荷載阻力系數(shù)設(shè)計(jì)法和允許應(yīng)力設(shè)計(jì)法中的系數(shù)K的計(jì)算。</p><p>　　在各種高級(jí)分析法中，包括塑性區(qū)準(zhǔn)塑性鉸法，彈性區(qū)塑性鉸法，名義

13、負(fù)荷塑性鉸法和改進(jìn)塑性鉸法，推薦使用改進(jìn)塑性鉸法，因?yàn)樗Ａ袅擞?jì)算的效率和簡(jiǎn)便性及實(shí)際應(yīng)用的準(zhǔn)確度。這個(gè)方法是對(duì)簡(jiǎn)單的傳統(tǒng)的彈塑性鉸法的改進(jìn)。其中包括一個(gè)簡(jiǎn)單的修改，證明在塑性鉸位置截面剛度的逐步退化和包括細(xì)部?jī)蓚€(gè)塑性鉸之間的逐步剛度退化。</p><p>　　表28.1中對(duì)常規(guī)荷載抗力系數(shù)法和高級(jí)實(shí)用性分析方法的關(guān)鍵因素做了比較。荷載抗力系數(shù)方法用來證明主要影響隱含在其柱強(qiáng)度和梁柱相互作用方程之中，而高級(jí)分析法

14、通過穩(wěn)定性的功能，剛度退化的功能和幾何缺陷方面來證明那些影響，在28.2中有詳細(xì)討論。</p><p>　　高級(jí)分析法持有許多鋼結(jié)構(gòu)實(shí)際問題的答案，同樣地，我們推薦尋找有效地合理地完成框架設(shè)計(jì)方法提供給工程師，但這要符合荷載抗力系數(shù)規(guī)范。在下面的章節(jié)里，我們將提出符合荷載抗力系數(shù)鋼框架結(jié)構(gòu)設(shè)計(jì)的高級(jí)先進(jìn)實(shí)用分析方法。該方法的有效性將通過比較基于精確塑性區(qū)解決方案和荷載抗力系數(shù)設(shè)計(jì)分析及設(shè)計(jì)結(jié)果的細(xì)部和框架的實(shí)際案

15、例研究。大范圍的案例研究和比較可以這種高級(jí)方法的有效性。</p><p><b>　　2．高級(jí)實(shí)用性分析</b></p><p>　　本節(jié)介紹了一種消除規(guī)范單獨(dú)構(gòu)件能力檢測(cè)的直接設(shè)計(jì)鋼框架的高級(jí)實(shí)用性分析方法。改進(jìn)后的塑性鉸法是由簡(jiǎn)單的傳統(tǒng)的彈塑性鉸法發(fā)展調(diào)整而來，實(shí)現(xiàn)了簡(jiǎn)單和真實(shí)的反映了實(shí)際情況。下一節(jié)將提供了最終確認(rèn)該方法的有效性的核查方法。</p>

16、<p>　　高級(jí)分析能夠驗(yàn)證連接的靈活性。常規(guī)分析和鋼結(jié)構(gòu)的設(shè)計(jì)通常在假設(shè)梁柱連接不是完全剛性或理想的固定下進(jìn)行。然而，在大部分實(shí)際的連接是半剛性的并且它們的狀態(tài)介于這兩個(gè)極端的例子之間。在允許應(yīng)力設(shè)計(jì)-荷載抗力系數(shù)規(guī)范，有兩類特定的建筑：FR（完全受限）結(jié)構(gòu)和PR（部分受限）結(jié)構(gòu)。荷載抗力系數(shù)規(guī)范允許通過“合理途徑”連接靈活性評(píng)估。</p><p>　　瞬間旋轉(zhuǎn)的關(guān)系代表了連接的狀態(tài)，已經(jīng)完成多方面

17、的試點(diǎn)連接工作和收集大批的瞬時(shí)旋轉(zhuǎn)數(shù)據(jù)。有了這個(gè)數(shù)據(jù)庫(kù)，研究人員已經(jīng)開發(fā)了數(shù)個(gè)連接模型，包括線性，多項(xiàng)式，B曲線，動(dòng)力和指數(shù)。鑒于此，Kishi和Chen提出的三參數(shù)冪函數(shù)模型被采用了。</p><p>　　在使用高級(jí)分析時(shí)，幾何缺陷必須由框架單元加以塑造。幾何缺陷在構(gòu)造或架設(shè)過程中導(dǎo)致不可避免的錯(cuò)誤。對(duì)于建筑結(jié)構(gòu)的結(jié)構(gòu)構(gòu)件，幾何缺陷的種類屬于非線性和非垂直的。明確建模和等效名義載荷被研究人員用來證明幾何缺陷。在

18、這一章節(jié)中，發(fā)展了基于進(jìn)一步減小構(gòu)件切線剛度的新方法。這種方法提供了一種簡(jiǎn)易的途徑用來證明沒有輸入名義載荷或明確幾何缺陷的不完善的影響。</p><p>　　本節(jié)中描述的高級(jí)實(shí)用性分析方法僅限于受靜載的兩維支撐，無支撐，和半剛架。不考慮結(jié)構(gòu)的空間狀態(tài)，并且假定有足夠的側(cè)向支撐防止側(cè)扭屈曲。假設(shè)W節(jié)就是這樣的節(jié)可以在無局部屈曲情況下發(fā)揮全塑性時(shí)刻能力。強(qiáng)軸和弱軸彎曲寬凸緣部分的研究都采用高級(jí)實(shí)用性分析方法。該方法可

19、被視為介于現(xiàn)在廣泛使用的常規(guī)荷載抗力系數(shù)方法和像在未來實(shí)際應(yīng)用中塑性區(qū)的制定方法等的更嚴(yán)謹(jǐn)?shù)母呒?jí)分析/設(shè)計(jì)方法之間的一個(gè)臨時(shí)的分析設(shè)計(jì)方法。</p><p>　　An Innovative Design for Steel Frame</p><p>　　Using Advanced Analysis</p><p>　　Introduction </p>

20、;<p>　　The steel design methods used in the U.S. are allowable stress design (ASD), plastic design (PD), and load and resistance factor design (LRFD). In ASD, the stress computation is based on a first-order elast

21、ic analysis, and the geometric nonlinear effects are implicitly accounted for in the member design equations. In PD, a first-order plastic-hinge analysis is used in the structural analysis. PD allows inelastic force redi

22、stribution throughout the structural system. Since geometric nonlinearity </p><p>　　The strength and stability of a structural system and its members are related, but the interaction is treated separately in

23、 the current American Institute of Steel Construction (AISC)-LRFD specification [2]. In current practice, the interaction between the structural system and its members is represented by the effective length factor. This

24、aspect is described in the following excerpt from SSRC Technical Memorandum No. 5 [28]:</p><p>　　Although the maximum strength of frames and the maximum strength of component members are interdependent (but

25、not necessarily coexistent), it is recognized that in many structures it is not practical to take this interdependence into account rigorously. At the same time, it is known that difficulties are encountered in complex f

26、rameworks when attempting to compensate automatically in column design for the instability of the entire frame (for example, by adjustment of column effective length). Th</p><p>　　This design approach is mar

27、ked in Figure 28.1 as the indirect analysis and design method.</p><p>　　In the current AISC-LRFD specification [2], first-order elastic analysis or second-order elastic analysis is used to analyze a structur

28、al system. In using first-order elastic analysis, the first-order moment is amplified by B1 and B2 factors to account for second-order effects. In the specification, the members are isolated from a structural system, and

29、 they are then designed by the member strength curves and interaction equations as given by the specifications, which implicitly account for seco</p><p>　　In order to account for the influence of a structura

30、l system on the strength of individual members, the effective length factor is used, as illustrated in Figure 28.2. The effective length method generally provides a good design of framed structures. However, several diff

31、iculties are associated with the use of the effective length method, as follows:</p><p>　　1. The effective length approach cannot accurately account for the interaction between the structural system and its

32、members. This is because the interaction in a large structural system is too complex to be represented by the simple effective length factor K. As a result, this method cannot accurately predict the actual required stren

33、gths of its framed members.</p><p>　　2. The effective length method cannot capture the inelastic redistributions of internal forces in a structural system, since the first-order elastic analysis with B1 and

34、B2 factors accounts only for second-order effects but not the inelastic redistribution of internal forces. The effective length method provides a conservative estimation of the ultimate load-carrying capacity of a large

35、structural system.</p><p>　　3. The effective length method cannot predict the failure modes of a structural system subject to a given load. This is because the LRFD interaction equation does not provide any

36、information about failure modes of a structural system at the factored loads.</p><p>　　4. The effective length method is not user friendly for a computer-based design.</p><p>　　5. The effective

37、length method requires a time-consuming process of separate member capacity checks involving the calculation of K factors.</p><p>　　With the development of computer technology, two aspects, the stability of

38、separate members and the stability of the structure as a whole, can be treated rigorously for the determination of the maximum strength of the structures. This design approach is marked in Figure 28.1 as the direct analy

39、sis and design method. The development of the direct approach to design is called advanced analysis, or more specifically, second-order inelastic analysis for frame design. In this direct approach, there i</p><

40、;p>　　The advantages of advanced analysis in design use are outlined as follows:</p><p>　　1. Advanced analysis is another tool for structural engineers to use in steel design, and its adoption is not manda

41、tory but will provide a flexibility of options to the designer.</p><p>　　2. Advanced analysis captures the limit state strength and stability of a structural system and its individual members directly, so se

42、parate member capacity checks encompassed by the specification equations are not required.</p><p>　　3. Compared to the LRFD and ASD, advanced analysis provides more information of structural behavior by dire

43、ct inelastic second-order analysis.</p><p>　　4. Advanced analysis overcomes the difficulties due to incompatibility between the elastic global analysis and the limit state member design in the conventional L

44、RFD method.</p><p>　　5. Advanced analysis is user friendly for a computer-based design, but the LRFD and ASD are not, since they require the calculation of K factor on the way from their analysis to separate

45、 member capacity checks.</p><p>　　6. Advanced analysis captures the inelastic redistribution of internal forces throughout a structural system, and allows an economic use of material for highly indeterminate

46、 steel frames.</p><p>　　7. It is now feasible to employ advanced analysis techniques that have been considered impractical for design office use in the past, since the power of personal computers and enginee

47、ring workstations is rapidly increasing.</p><p>　　8. Member sizes determined by advanced analysis are close to those determined by the LRFD method, since the advanced analysis method is calibrated against th

48、e LRFD column curve and beam-column interaction equations. As a result, advanced analysis provides an alternative to the LRFD.</p><p>　　9. Advanced analysis is time effective since it completely eliminates t

49、edious and often confused member capacity checks, including the calculation of K factors in the LRFD and ASD.</p><p>　　Among various advanced analyses, including plastic-zone, quasi-plastic hinge, elastic-pl

50、astic hinge, notional-load plastic-hinge, and refined plastic hinge methods, the refined plastic hinge method is recommended, since it retains the efficiency and simplicity of computation and accuracy for practical use.

51、The method is developed by imposing simple modifications on the conventional elastic-plastic hinge method. These include a simple modification to account for the gradual sectional stiffness de</p><p>　　The k

52、ey considerations of the conventional LRFD method and the practical advanced analysis method are compared in Table 28.1. While the LRFD method does account for key behavioral effects implicitly in its column strength and

53、 beam-column interaction equations, the advanced analysis method accounts for these effects explicitly through stability functions, stiffness degradation functions, and geometric imperfections, to be discussed in detail

54、in Section 28.2.</p><p>　　Advanced analysis holds many answers to real behavior of steel structures and, as such, we recommend the proposed design method to engineers seeking to perform frame design in effic

55、iency and rationality, yet consistent with the present LRFD specification. In the following sections, we will present a practical advanced analysis method for the design of steel frame structures with LRFD. The validity

56、of the approach will be demonstrated by comparing case studies of actual members and frames with th</p><p>　　2．Practical Advanced Analysis </p><p>　　This section presents a practical advanced an

57、alysis method for the direct design of steel frames by eliminating separate member capacity checks by the specification. The refined plastic hinge method was developed and refined by simply modifying the conventional ela

58、stic-plastic hinge method to achieve both simplicity and a realistic representation of actual behavior [15, 25]. Verification of the method will be given in the next section to provide final confirmation of the validity

59、of the method.</p><p>　　Connection flexibility can be accounted for in advanced analysis. Conventional analysis and design of steel structures are usually carried out under the assumption that beam-to-column

60、 connections are either fully rigid or ideally pinned. However, most connections in practice are semi-rigid and their behavior lies between these two extreme cases. In the AISC-LRFD specification [2], two types of constr

61、uction are designated: Type FR (fully restrained) construction and Type PR (partially restrained)</p><p>　　Connection behavior is represented by its moment-rotation relationship. Extensive experimental work

62、on connections has been performed, and a large body of moment-rotation data collected. With this data base, researchers have developed several connection models, including linear, polynomial, B-spline, power, and exponen

63、tial. Herein, the three-parameter power model proposed by Kishi and Chen [21] is adopted.</p><p>　　Geometric imperfections should be modeled in frame members when using advanced analysis. Geometric imperfect

64、ions result from unavoidable error during fabrication or erection. For structural members in building frames, the types of geometric imperfections are out-of-straightness and out-of-plumbness. Explicit modeling and equiv

65、alent notional loads have been used to account for geometric imperfections by previous researchers. In this section, a new method based on further reduction of the tangent </p><p>　　The practical advanced an

66、alysis method described in this section is limited to two-dimensional braced, unbraced, and semi-rigid frames subject to static loads. The spatial behavior of frames is not considered, and lateral torsional buckling is a

67、ssumed to be prevented by adequate lateral bracing. A compact W section is assumed so sections can develop full plastic moment capacity without local buckling. Both strong- and weak-axis bending of wide flange sections h