土木工程毕业设计开题报告91412

南昌大学科技学院本科毕业设计（论文）

开题报告

题目

江西某市行政办公楼设计

专

业土木工程

班

级

土木102

班

学生

姓名余欣欣

学

号

701321006

9

指导

教师潘固村

职

称中级职称

南昌大学科技学院教务部制

南昌大学科技学院本科毕业设计（论文）开题报告

Assessment of European seismic design procedures

for steel framed structures

A.Y. Elghazouli

1 Introduction

Although seismic design has bene?ted from substantial developments in recent years, the

need to offer practical and relatively unsophisticated design procedures inevitably results in various simpli?cations 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 apprai sed 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 modi?ca- tion factor) which is used to reduce the code-speci?ed 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-de?ned plastic mechanism (often referred to as failure mode), coupled with the provision of suf?cient 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 con?g- 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 observ ations and ?ndings. Amongst the various aspects examined in this paper, particular emphasis is given to capacity design veri?cations 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 clari?cations and possible modi?cations 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 speci?c 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 de?nes 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 (η) and pre-de?ned 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 acc elerations are divided by ‘q ’ (excepting some modi?cations for T < TB), to reduce the design forces in accordance with the structural con?guration and expected ductility. For regular structures (satisfying a number of code-speci?ed criteria), a simpli?e d 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 seis micity, a ‘q ’ of 1.5–2.0 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 classi?ed 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)已经进化数年，最近从一个准标准地位改变了欧洲标准。代码明确采用能力设计方法,及相应程序方面的失效方式控制力的减少和延性需求。其中最主要的优点是相比于其它地震规定,它的成功在很大程度上在维持直接和明确的关系设计的具体程序和整体能力设计的概念。

有两个基本的设计水平,即考虑无倒塌'和損害降低,实质上是指最终和极限

状态,分别,地震作用下。无倒塌技术对应的地震作用的要求推荐的概率的基础上对10%在未来的50年里, 或重现期公元前475年的价值观,而与之关联的損害降低水平相关的概率是赞扬10%在10年内,或重现期95年了。正如人们所预料的那样,能力设计的程序都被更直接地联系在一起的极限状态,但都包含了大量的检查,以确保符合适用性条件。这个时期的振动(T)和设计地面加速度(ag)在坚固的地面上。弹性频谱取决于土壤因子(S),阻尼校正因子(η)和预案光谱周期(肺结核,血中总胆固醇及TD)依次取决于土壤类型和地震的来源特征。最终的极限状态设计,为球墨铸铁性能无弹性拌匀通过使用此行为因子(q),在过去的版本的EC8是假定捕获作用阻尼。从本质上说,为了避免表演无弹性分析在设计、弹性谱加速度被“问”(除某些修改为T < TB)、降低设计力量依照结构配置和预期的延性。常规结构(满足一定数量的指定代码准则),一个简化的等效静态方法可采用主要基于

的基本模式振动。

2.2行为因素

在这项研究中,虽然有些评论有关它的行为是在讨论。同时,k形帧的,没有考虑到在内,因为它们是不推荐使用对耗散的设计。另一方面,特别支撑帧,抗力矩可以结合的优点和同心支撑帧在条款高延性和刚度的都超出了本研究的范围。参考行为因素应该被视为一个上界即使非线性的动态分析提出更高的价值。常规结构领域的,低地震活动性的方式,也可采用无申请1.5 - 2.0设计程序,认识到耗散一个最低水平的存在固有的超负荷和延性。在这种情况下,构成的-真正的会被视作是延展性差(DCL),在全球弹性分析即可被利用,和电阻的成员和连接端口可以评价

根据2005年Eurocode EC3(3),没有任何附加要求。