土木工程 外文翻译 外文文献 英文文献 欧洲对钢框架结构抗震设计的评估.doc

题 目出 处/ content/b35k24747458435l/ 英文原文：Assessment of European seismic design proceduresfor steel framed structuresA.Y. Elghazouli1 Introduction Although seismic design has beneted from substantial developments in recent 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 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 procedures 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 former, 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 inelastic 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 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 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 procedures 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 guidance, 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. 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 warrant 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 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 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-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 associated 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 serviceability 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 periods (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 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 number 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 are not considered herein as they are not recommended for dissipative design. On the other hand, eccentrically-braced frames which can combine the advantages of moment-resisting and concentrically-braced frames in terms of high ductility and stiffness, are beyond the scope of this study. The reference behaviour factor should be considered as an upper bound even if non-linear dynamic analysis suggests higher values. For regular structures in areas of low seismicity, a q of 1.52.0 may be adopted without applying dissipative design procedures, recognizing the presence of a minimal level of inherent over-strength and ductility. In this case, the struc- ture would be classied as a low ductility class (DCL) for which global elastic analysis can be utilized, and the resistance of members and connections may be evaluated according to EC3 (Eurocode 3 2005) without any additional requirements. 中文翻译：欧洲对钢框架结构抗震设计的评估1介绍虽然抗震设计实质性进展受益匪浅,近年来,需要提供实用和相对简单的设计方法,不可避免地导致各种各样的简化和理想化。这些假设,某些情况下,有广告影响预期的抗震性能,因此在合理性和可靠性设计的方法下。有必要的设计概念和应用不断评估和修改规则是根据最近的研究和对地震的行为改进的理解。为此,本文在评估潜在的方法和主要流程采用钢结构工程的抗震设计中,用强调欧洲设计规定,制定本规定。按照现行的抗震设计实践,这在欧洲被表示Eurocode 8(EC8)(2004),结构也可以设计出系统根据或耗散行为。这位前,藉此结构尺寸进行回应主要集中在弹性范围内,通常是有限的地区地震活动或结构的低特殊用途与重要性。否则,编码的目的是要实现节约型设计被耗散行为在相当大的弹性变形能得到满足在重大的地震事件。在案件的不规则或复杂的结构,详细的非-线性动态的分析可能是必要的。然而,常规结构设计的系统具有耗散通过指定一个经常表演结构行为因素(例如力量还原或修改因素),用它来减少所造成的指定代码，正如有弹性响应谱。这是进行结合的能力设计概念,需要采用一种适宜的容量的确定基于一个预先定义的结构塑料机械(通常称为失效模式),伴随着提供充分的在塑性区和足够的延性等因素为其它地区。虽然基本设计原则的能力设计可能不是故意在各种不同实际的程序代码,可以在常随因为不同的行为假设理想化和理想化设计。摘要本文检视主要设计方法和行为方面的抗力矩典型配置和中心支撑帧。虽然这项研究主要在欧洲的指导下,我们的讨论也涉及到规定(以1999年,2002年,2003 2005a,b作比较)。在适当的地方,简单的解析治疗，为了说明了引人注目的行为方面和发展趋势参考。最近的实验观测也做了各种努力和成果。重点是给设计验证作为相关要求的含义,时刻帧后屈曲行为和延性需求的支撑框架,因为这些代表问题,谨慎的解释和考虑的设计过程。因此,一定数量的必要的澄清和可能的修改代码程序提出了2种通常的考虑。2.1极限状态和加载的标准欧洲的抗震规范,EC8(Eurocode 8 2004年)已经进化数