土木工程(抗震)外文翻译----欧洲对钢框架结构抗震设计的评估

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1、 本科生毕业设计 外文翻译 题 目 出 处 http:/ content/b35k24747458435l/ 姓 名 学 号 00000000 学 院 XX 学院 专 业 XX 工程 指导教师 2011 年 X 月 X 日 英文原文： Assessment of European seismic design procedures for steel framed structures A.Y. Elghazouli 1 Introduction Although seismic design has beneted from substantial developments in recen

2、t years, the need to offer practical and relatively unsophisticated design procedures inevitably results in various simplications and idealisations. These assumptions can, in some cases, have advert implications on the expected seismic performance and hence on the rationale and reliabil- ity of the

3、design approaches. It is therefore imperative that design concepts and application rules are constantly appraised and revised in light of recent research ndings and improvedunderstanding of seismic behaviour. To this end, this paper focuses on assessing the under- lying approaches and main procedure

4、s adopted in the seismic design of steel frames, with emphasis on European design provisions. In accordance with current seismic design practice, which in Europe is represented by Eurocode 8 (EC8) (2004), structures may be designed according to either non-dissipative or dissipative behaviour. The fo

5、rmer, through which the structure is dimensioned to respond largely in the elastic range, is normally limited to areas of low seismicity or to structures of special use and importance. Otherwise, codes aim to achieve economical design by employ- ing dissipative behaviour in which considerable inelas

6、tic deformations can be accommodated under significant seismic events. In the case of irregular or complex structures, detailed non- linear dynamic analysis may be necessary. However, dissipative design of regular structures is usually performed by assigning a structural behaviour factor (i.e. force

7、 reduction or modica- tion factor) which is used to reduce the code-specied forces resulting from idealised elastic response spectra. This is carried out in conjunction with the capacity design concept which requires an appropriate determination of the capacity of the structure based on a pre-dened

8、plastic mechanism (often referred to as failure mode), coupled with the provision of sufcient ductility in plastic zones and adequate over-strength factors for other regions. Although the fundamental design principles of capacity design may not be purposely dissimilar in various codes, the actual pr

9、ocedures can often vary due to differences in behavioural assumptions and design idealisations. This paper examines the main design approaches and behavioural aspects of typical cong- urations of moment-resisting and concentrically-braced frames. Although this study focuses mainly on European guidan

10、ce, the discussions also refer to US provisions (AISC 1999, 2002, 2005a,b) for comparison purposes. Where appropriate, simple analytical treatments are presented in order to illustrate salient behavioural aspects and trends, and reference is also made to recent experimental observations and ndings.

11、Amongst the various aspects examined in this paper, particular emphasis is given to capacity design verications as well as the implications of drift-related requirements in moment frames, and to the post-buck- ling behaviour and ductility demand in braced frames, as these represent issues that warra

12、nt cautious interpretation and consideration in the design process. Accordingly, a number of necessary clarications and possible modications to code procedures are put forward. 2 General considerations 2.1 Limit states and loading criteria The European seismic code, EC8 (Eurocode 8 2004) has evolved

13、 over a number of years changing status recently from a pre-standard to a full European standard. The code explicitly adopts capacity design approaches, with its associated procedures in terms of failure mode control, force reduction and ductility requirements. One of the main merits of the code is

14、that, in comparison with other seismic provisions, it succeeds to a large extent in maintaining a direct and unambiguous relationship between the specic design procedures and the overall capacity design concept. There are two fundamental design levels considered in EC8, namely no-collapse and damage

15、-limitation, which essentially refer to ultimate and serviceability limit states, respec- tively, under seismic loading. The no-collapse requirement corresponds to seismic action based on a recommended probability of exceedance of 10% in 50 years, or a return period of 475 years, whilst the values a

16、ssociated with the damage-limitation level relate to arecommended probability of 10% in 10 years, or return period of 95 years. As expected, capacity design procedures are more directly associated with the ultimate limit state, but a number of checks are included to ensure compliance with serviceabi

17、lity conditions. The code denes reference elastic response spectra (Se) for acceleration as a function of the period of vibration (T) and the design ground acceleration (ag) on rm ground. The elastic spectrum depends on the soil factor (S), the damping correction factor () and pre-dened spectral per

18、iods (TB , TC and TD) which in turn depend on the soil type and seismic source characteristics. For ultimate limit state design, inelastic ductile performance is incorporated through the use of the behaviour factor (q) which in the last version of EC8 is assumed to capture also the effect of viscous

19、 damping. Essentially, to avoid performing inelastic analysis in design, the elastic spectral accelerations are divided by q (excepting some modications for T TB), to reduce the design forces in accordance with the structural conguration and expected ductility. For regular structures (satisfying a n

20、umber of code-specied criteria), a simplied equivalent static approach can be adopted, based largely on the fundamental mode of vibration. 2.2 Behaviour factors This type of frame has special features that are not dealt with in this study, although some comments relevant to its behaviour are made within the discussions. Also, K-braced frames