外文翻译.docx

1、外文翻译 毕业设计（论文） 外文翻译 设计（论文）题目： 鄞西小学4号教学楼 结构设计与预算 学 院 名 称： 建筑工程学院 专 业： 土木工程 班 级： 房建-071 姓 名： 娄佳君 学 号 07404010214 指 导 教 师： 袁坚敏 职 称 讲师 2011年 2月 28 日外文原文： Lateral stiffness estimation in frames and its implementation to continuum modelsfor linear and nonlinear static analysisTuba Eroglu Sinan AkkarReceive

2、d: 23 April 2010 / Accepted: 17 November 2010 Springer Science+Business Media B.V. 2010Abstract Continuum model is a useful tool for approximate analysis of tall structures including moment-resisting frames and shear wall-frame systems. In continuum model, discrete buildings are simplified such that

3、 their overall behavior is described through the contributions of flexural and shear stiffnesses at the story levels. Therefore, accurate determination of these lateral stiffness components constitutes one of the major issues in establishing reliable continuum models even if the proposed solution is

4、 an approximation to actual structural behavior. This study first examines the previous literature on the calculation of lateral stiffness components (i.e. flexural and shear stiffnesses) through comparisons with exact results obtained from discrete models. A new methodology for adapting the heightw

5、ise variation of lateral stiffness to continuum model is presented based on these comparisons. The proposed methodology is then extended for estimating the nonlinear global capacity of moment resisting frames. The verifications that compare the nonlinear behavior of real systems with those estimated

6、 from the proposed procedure suggest its effective use for the performance assessment of large building stocks that exhibit similar structural features. This conclusion is further justified by comparing nonlinear response history analyses of single-degree-of-freedom (sdof) systems that are obtained

7、from the global capacity curves of actual systems and their approximations computed by the proposed procedure.Keywords Approximate nonlinear methods Continuum model Global capacity Nonlinear response Frames and dual systemsT. ErogluDepartment of Civil Engineering, Akdeniz University, 07058 Antalya,

8、Turkeye-mail: etubametu.edu.trS. Akkar (B)Department of Civil Engineering, Middle East Technical University, 06531 Ankara, Turkeye-mail: sakkarmetu.edu.tr1 IntroductionReliable estimation of structural response is essential in the seismic performance assessment and design because it provides the maj

9、or input while describing the global capacity of structures under strong ground motions.With the advent of computer technology and sophisticated structural analysis programs, the analysts are now able to refine their structural models to compute more accurate structural response. However, at the exp

10、ense of capturing detailed structural behavior, the increased unknowns in modeling parameters, when combined with the uncertainty in ground motions, make the interpretations of analysis results cumbersome and time consuming. Complex structural modeling and response history analysis can also be overw

11、helming for performance assessment of large building stocks or the preliminary design of new buildings. The continuum model, in this sense, is an accomplished approximate tool for estimating the overall dynamic behavior of moment resisting frames (MRFs) and shear wall-frame (dual) systems. Continuum

12、 model, as an approximation to complex discrete models, has been used extensively in the literature. Westergaard (1933) used equivalent undamped shear beam concept for modeling tall buildings under earthquake induced shocks through the implementation of shear waves propagating in the continuum media

13、. Later, the continuous shear beam model has been implemented by many researchers (e.g. Iwan 1997; Glkan and Akkar 2002; Akkar et al. 2005; Chopra and Chintanapakdee 2001) to approximate the earthquake induced deformation demands on frame systems. The idea of using equivalent shear beams was extende

14、d to the combination of continuous shear and flexural beams by Khan and Sbarounis (1964).Heidebrecht and Stafford Smith (1973) defined a continuum model (hereinafter HS73) for approximating tall shear wall-frame type structures that is based on the solution of a fourthorder partial differential equa

15、tion (PDE). Miranda (1999) presented the solution of this PDE under a set of lateral static loading cases to approximate the maximum roof and interstory drift demands on first-mode dominant structures. Later, Heidebrecht and Rutenberg (2000) showed a different version of HS73 method to draw the uppe

16、r and lower bounds of interstory drift demands on frame systems. Miranda and Taghavi (2005) used the HS73 model to acquire the approximate structural behavior up to 3 modes. As a follow up study, Miranda and Akkar (2006) extended the use of HS73 to compute generalized drift spectrum with higher mode

17、 effects. Continuum model is also used for estimating the fundamental periods of high-rise buildings (e.g. Dym and Williams 2007). More recently, Gengshu et al. (2008) studied the second order and buckling effects on buildings through the closed form solutions of continuous systems. While the theore

18、tical applications of continuum model are abundant as briefly addressed above, its practical implementation is rather limited as the determination of equivalent flexural (EI) and shear (GA) stiffnesses to represent the actual lateral stiffness variation in discrete systems have not been fully addres

19、sed in the literature. This flaw has also restricted the efficient use of continuum model beyond elastic limits because the nonlinear behavior of continuum models is dictated by the changes in EI and GA in the post-yielding stage This paper focuses on the realistic determination of lateral stiffness

20、 for continuum models. EI and GA defined in discrete systems are adapted to continuum models through an analytical expression that considers the heightwise variation of boundary conditions in discrete systems. The HS73 model is used as the base continuum model since it is capable of representing the

21、 structural response between pure flexure and shear behavior. The proposed analytical expression is evaluated by comparing the deformation patterns of continuum model and actual discrete systems under the first-mode compatible loading pattern. The improvements on the determination of EI and GA are c

22、ombined with a second procedure that is based on limit state analysis to describe the global capacity of structures responding beyond their elastic limits. Illustrative case studies indicate that the continuum model, when used together with the proposed methodologies, can be a useful tool for linear

23、 and nonlinear static analysis.2 Continuum model characteristics The HS73 model is composed of a flexural and shear beam to define the flexural (EI) and shear (GA) stiffness contributions to the overall lateral stiffness. Themajor model parameters EI and GA are related to each other through the coef

24、ficient (Eq.1). As goes to infinity the model would exhibit pure shear deformation whereas = 0 indicates pure flexural deformation. Note that it is essential to identify the structural members of discrete buildings for their flexural and shear beam contributions because the overall behavior of conti

25、nuum model is governed by the changes in EI and GA. Equation 2 shows the computation of GA for a single column member in HS73. The variables Ic and h denote the column moment of inertia and story height, respectively. The inertia terms Ib1 and Ib2 that are divided by the total lengths l1 and l2, res

26、pectively, define the relative rigidities of beams adjoining to the column from top (see Fig. 3 in the referred paper). Equation 2 indicates that GA (shear component of total lateral stiffness) is computed as a fraction of flexural stiffness of frames oriented in the lateral loading direction. Accor

27、dingly, the flexural part (EI) of total stiffness is computed either by considering the shear-wall members in the loading direction and/or other columns that do not span into a frame in the direction of loading. This assumption works fairly well for dual systems. However, it may fail in MRFs because

28、 it will discard the flexural contributions of columns along the loading direction and will lump total lateral stiffness into GA. Essentially, this approximation will reduce the entire MRF to a shear beam that would be an inaccurate way of describing MRF behavior unless all beams are assumed to be r

29、igid. To the best of authors knowledge, studies that useHS73model do not describe the computation of in depthwhile representing discrete building systems as continuum models. In most cases these studies assign generic values for describing different structural behavior spanning from pure flexure to

30、pure shear1. This approach is deemed to be rational to represent theoretical behavior of different structures. However, the above highlighted facts about the computation of lateral stiffness require further investigation to improve the performance of HS73 model while simplifying an actual MRF as a c

31、ontinuum model. In that sense, it is worthwhile to discuss some important studies on the lateral stiffness estimation of frames. These could be useful for the enhanced calculations of EI and GA to describe the total lateral stiffness in continuum systems.3 Lateral stiffness approximations for MRFs T

32、here are numerous studies on the determination of lateral stiffness in MRFs. The methods proposed in Muto (1974) and Hosseini and Imagh-e-Naiini (1999) (hereinafter M74 and HI99, respectively) are presented in this paper and they are compared with the HS73 approach for its enhancement in describing the lateral deformation behavior of structural systems. Equation 3 shows the total lateral stiffness, k, definition of M74 for a column at an intermediate story. The parameters Ic, h, Ib1, Ib2, l1 and l2 have the samemeanings as in Eq. (2). Note that Eq. (2) p