屈曲约束支撑体系的应用与研究进展(Ⅱ)

屈曲约束支撑框架体系(BRBF)是新近发明并逐渐得到应用的一种框架体系。因为屈曲约束支撑(BRB)在受拉和受压时都可屈服而不屈曲,因此克服了传统支撑体系的缺点。第二部分简要介绍了SEAOC-AISC提出的反复加载试验要求,介绍了BRB各组成部分、BRB构件本身及BRBF体系的性能。以及BRBF的设计方法。     

屈曲约束支撑体系的应用与研究进展(Ⅰ)

屈曲约束支撑框架体系(BRBF)是新近发明并逐渐得到应用的一种抗震框架体系。因为屈曲约束支撑(BRB)在受拉和受压时都可屈服而不屈曲,因此克服了传统支撑体系的缺点。本文分两部分,第一部分主要介绍其基本原理和各组成部分的概况、BRBF的特点,还简要介绍了该体系在各国家和地区应用和研究的进展情况。     

偏心支撑框架的设计计算方法

我国《建筑抗震设计规范》(GB5 0 0 11- 2 0 0 1)规定 ,8度以上宜采用偏心支撑 ,但我国至今没有一个自行设计的工程用过这种支撑。参考美国计算例题、相关规范 ,并依据我国规范 ,对偏心支撑框架的实际计算方法进行讨论 ,总结出适合我国规范和实际情况的偏心支撑框架设计计算方法。其中 ,重点介绍了各杆件的内力计算、消能梁段的设计、非消能梁段的设计、支撑的设计、柱的设计等 ,给工程设计提供理论基础和实用方法 ,有助于设计人员对该体系设计过程的了解和此种支撑的推广应用     

偏心BRBFs的抗震性能分析

为了解偏心屈曲约束支撑钢框架（BRBFs）的抗震性能,运用pkpm设计软件设计门架式偏心BRBFs和人字形偏心BRBFs两种结构,基于大型有限元软件ANSYS对两种结构进行有限元数值模拟,分析了两种结构在基本烈度作用下的各层位移反应及层间位移角,结果表明,两种结构变形受低阶振型影响较大,沿高度呈倒三角地形分布,结构变形为弯剪形,各层位移及层间位移角均满足规范要求,体现出良好的抗震性能。构件产生塑性变形而耗能时,可以将结构构件等效为结构阻尼进行分析,介绍了等效阻尼比的求解方法。通过对罕遇地震作用下的两种结构的最大层间位移角、层间剪力及顶层位移时程的研究进一步评估两种结构的抗震性能,研究表明,在罕遇地震作用下,人字形偏心BRBFs的抗震性能较好。     

Recent research on eccentrically braced frames

Recent research developments on eccentrically braced steel frames for seismic design are reviewed. The emphasis is placed on the design of links, which are short sections of beams between columns and braces, and similar elements at eccentric joints. The review includes some highlights of the latest experiments with one-third scale models employing different eccentric bracing schemes, an updated classification of links, and special design requirements for different types of links. Some results are given on recent cyclic tests of full-size links.     

美国ANSI/AISC SSPEC-2002《钢结构建筑抗震设计规定》介绍(4)

20 0 2年 1月 31日 ,美国钢结构协会 (AISC)和AISC规范委员会正式批准发布《钢结构建筑抗震设计规定》。本文为《钢结构建筑抗震设计规定》介绍 (3)之续篇 ,对“规定”中“钢结构建筑”部分的第 13～ 16章节 ,包括特殊中心支撑抗弯框架 (SCBF)、普通中心支撑抗弯框架 (OCBF)和偏心支撑抗弯框架 (EBF)方面的有关内容进行了介绍并作了必要的说明。     

BRBFs的结构影响系数研究方法初探

应用ANSYS软件对一屈曲约束支撑钢框架算例进行数值模拟,基于增量动力分析法,初步探讨了屈曲约束支撑钢框架的结构影响系数。结果表明,结构超强系数对结构影响系数的影响远大于结构延性折减系数,在结构影响系数的构成中结构超强系数占主导地位。     

偏心支撑钢框架延性抗震设计探讨

偏心支撑钢框架结构体系是一种非常适合强震地区的抗震结构体系.国内外许多高层建筑采用了该结构体系,尤其在美国与日本的高地震烈度地区.国内外现行规范对该体系的设计均未能充分体现其良好的延性与耗能能力,但只有通过结构的延性设计才能使结构真正具有耗能能力.本文从不同支撑类型的刚度、高跨比、延性和双重体系探讨了支撑类型的选择与布置形式,分析了耗能梁长度与截面设计以及耗能梁与支撑、柱的连接形式对偏心支撑钢框架结构体系延性和耗能能力的影响,提出了偏心支撑钢框架结构体系延性抗震设计的建议与思路,为规范修订和工程应用提供一些参考.     

偏心支撑钢框架设计方法

着重阐述了消能梁段的设计方法 ,其中包括消能梁段的长度确定和截面选择 ,消能梁段的腹板加劲肋、连接和侧向支撑的设计。并对消能梁段以外其它构件的设计方法进行了介绍 ,以增强工程设计人员对该结构体系的了解。     

钢筋混凝土框架抗震节点统一设计方法探讨

在过去３０年里，很多国家进行了大量的地震荷载作用下钢筋混凝土框架梁柱节点及连接方面的研究工作。在试验研究的基础上，设计方法不断产生并被编入到规范中。然而关于节点的性能和设计方法却存在着不同的意见和争论，因此很难对所有问题达成共识和建立统一的设计方法。根据作者对钢筋混凝土框架节点的研究成果和对国内外资料掌握的基础上，对框架抗震节点的统一设计方法进行了初步探讨。     

支撑形式对钢框架结构抗震性能影响

钢结构框架类型,按其抗侧力体系可以分为:纯框架(UBF)、中心支撑框架(CBF)和偏心支撑框架(EBF)。纯框架具有较好的延性,刚度较小,往往满足了抗震变形要求;支撑框架刚度较大,具有两道纯抗震防线,适应于抗震设防较高的地区。通过有限元软件ANSYS对6层框架进行动力分析,比较这三种框架的抗震性能。由分析可知,支撑框架能较好地控制结构变形。     

Genetic algorithm in locating the optimum mid-connection of Off-Centre braced system

In this article, a particular Off-Centre braced system is examined. This bracing system consists of three members, where the diagonal member is not straight and it is connected to the corner of the frame by a third member. The out-of-straightness of the diagonal member introduces eccentricity to the system. This system improves the energy dissipation due to earthquake as well as its eccentricity allows architects to have more openings in the panel areas. In this regard, the location of brace elements connection point has significant effect on the stiffness of the system. In order to assess the influence of the connection position and other parameters such as cross section of brace elements and span/height ratio of the braced frame on the stiffness of the system, analytical equations have been developed. A new method based on Genetic algorithm (GA) to obtain the connection point is also proposed. The importance of elite individuals together with selection, mutation and crossover operator between populations are also examined. In order to achieve the best and practical location of the connection point, two equations for boundary conditions with regards to the opening dimensions are set in a computer model developed in MATLAB program. The results indicate that the stiffness decreases as the connection point moves closer to the corner of the frame. Additionally, the proposed method is proven to be efficient in determining the connection point due to its accuracy and minimal computational time required compare to conventional trial and error method.     

Comparative study of special and ordinary braced frames

The collapse probability of ductile and non‐ductile concentrically braced frames was investigated using nonlinear dynamic response analysis. Two buildings with three and nine stories located in Boston and Los Angeles, respectively, were designed and subjected to ground motions from the areas. In Boston area, three‐story and nine‐story buildings were designed as ordinary concentrically braced frame with response modification reduction factor R equal to 3 1/4 to be considered as non‐ductile structural systems; comparatively, in Los Angeles area, three‐story and nine‐story buildings were designed as special concentrically braced frame with response modification reduction factor R equal to 6 to be considered as ductile structural systems. In order to evaluate the performance of ductile and non‐ductile concentrically braced frames in moderate and severe seismic regions, ATC‐63 would be used as reference to assess the seismic behaviors. Evaluation approach recommended by ATC‐63 was adopted, and hundreds of nonlinear dynamic analyses were performed. Through alternating the scale factors of designated ground motions, median of structural collapse intensity was presented for each structure. By observing the results of statistical performance assessment, the seismic performance of the systems was evaluated, and some observations are made based on the study. Copyright © 2012 John Wiley & Sons, Ltd.     

BRBFs的抗震性能分析

应用ANSYS软件对屈曲约束支撑钢框架(BRBFs)和普通支撑钢框架的抗震性能进行有限元数值模拟,分析了两种结构在基本烈度地震作用下和罕遇地震作用下的层位移、顶层加速度及层间相对位移等结构响应,结果表明,在小震作用下两种结构抗震性能均表现良好,但在罕遇地震作用下普通支撑钢框架由于支撑的平面外失稳,导致整个结构刚度退化,而屈曲约束支撑钢框架则能更加有效地控制结构的侧移,降低结构的地震响应。     

铰接中心支撑钢框架体系结构设计研究

在进行结构体系比较和振动台试验验证的基础上,确定了某大型电厂主厂房选用铰接中心支撑钢框架体系。对深化设计方案进行了地震响应的数值模拟研究。虽结构平面扭转和竖向质量分布均不规则,但考虑到多遇地震下没有构件屈服或失稳,且多遇、罕遇地震下的层间侧移角均满足规范要求,认为结构设计较为合理,可以满足"小震不坏"、"大震不倒"的抗震设防要求。同时也再次验证了只要设计合理,铰接中心支撑钢框架体系在8度抗震设防区仍可具有较好的抗震性能,高度也可以突破民用建筑12层的限制。最后给出了铰接中心支撑钢框架结构节点连接部分抗震设计的一些原则性建议。     

近断层脉冲型地震作用下防屈曲支撑-钢筋混凝土框架结构的抗震性能

具有向前方向性效应和滑冲效应的近断层脉冲型地震动对建筑结构的破坏已受到工程界的广泛关注。为了解设置防屈曲支撑（BRB）的混凝土框架在近断层脉冲型地震动激励下的抗震性能,采用基于能量平衡的塑性设计方法完成了3个V形BRB支撑的RC框架结构的抗震设计。分别选取具有向前方向性效应和滑冲效应的脉冲型以及非脉冲型三组共36条近断层地震动,对结构进行罕遇地震作用下的非线性动力分析,研究了结构的最大层间位移角、最大顶点加速度、最大顶点位移和BRB的轴向性能;分析和评估了结构在3条典型地震动激励下的地震响应。结果表明：近断层脉冲型地震动比非脉冲型地震动对结构会产生更大的地震响应,且响应显著集中于速度脉冲时刻;BRB能充分发挥其耗能特性,提高RC框架结构体系的抗震性能。     

Moment frames – concentrically braced frames dual systems: analysis of different design criteria

In this paper, a design methodology based on the theory of plastic mechanism control (TPMC) is presented for dual systems combined by moment resisting frames and concentrically braced frames (MRF–CBF dual systems). The study is focused on the design of structures failing in global mode, i.e. whose collapse mechanism is characterised by the yielding of all the tensile diagonals, the buckling of the compressed ones, and the development of plastic hinges at all the beam ends and at the base of first-storey columns. The results of push-over analyses and nonlinear dynamic analyses carried out with reference to MRF–CBF dual systems designed according to the proposed procedure are compared with those obtained with reference to the same structural scheme designed according to Eurocode 8. The advantages obtained in terms of seismic performances are outlined and also economic issues are investigated pointing out the convenience of seismic design based on TPMC.     

防屈曲支撑钢框架结构中被撑柱抗震设计探讨

通过3个算例,对采用人字形和V字形的无粘结内藏钢板支撑剪力墙(即人字形和V字形防屈曲支撑)的防屈曲支撑钢框架结构的抗震性能进行分析。重点考察大震下,支撑的轴力分布和对被撑柱所受轴力的影响。分析表明,采用结构在一阶振型下的支撑轴力分布来设计被撑柱的做法,适用于多层的防屈曲支撑钢框架结构;而对于高层的防屈曲支撑钢框架结构,高振型影响较显著,上述设计方法对被撑柱的设计较保守,有必要考虑高振型参与下的支撑轴力分布来设计被撑柱。