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。     

Numerical study of seismic performance of steel moment-resisting frame with buckling-restrained brace and viscous fluid damper

The seismic performance assessment of modified steel moment-resisting frame (SMRF) was carried out by nonlinear time-history analysis. The basic bare SMRF was reduced in strength first and then enhanced by installing passive energy dissipating devices (EDDs) to develop modified frame. Passive EDDs comprise both rate-dependent and rate-independent devices. Viscous fluid damper (VFD) is a rate-dependent device whereas buckling-restrained brace is a rate-independent device. The lateral strength of structure was improved by using these devices either alone or in combination. Seven-scaled time-history records were used for incremental dynamic analysis. The stiffness effect on the stories is demonstrated through the lateral displacement profile of the building. The VFD is found to be a good EDD as it significantly improved the performance of the frame at all levels of seismic analysis.     

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。     

Seismic performance of eccentrically braced frame with vertical link using PBPD method

There are special guidelines to design the structures resistant to earthquake forces; parameters such as conditions of the site, seismicity of the site, importance of the structure and the type of the structure are the main effective factors. Consideration of these parameters in calculation and distribution of the earthquake forces are significantly different in various design codes. In most of these design codes, the computation and distribution of earthquake forces are based upon the elastic structural analysis. In this approach, the real behavior of structure is not considered and it may consequently sustain big displacements and irretrievable damages. Therefore, a new design method has been utilized in this paper by which the base shear and its distribution in the height of the structure are calculated according to the plastic behavior of structure and takes advantage of energy balance. The latter is known as performance‐based plastic design method. The study of the behavior of eccentrically braced frames with vertical links while undertaking earthquake loads using performance‐based plastic design method is the main purpose of this study. It is also worthy of notion that the frames are designed using a capacity design method. In addition, the results are compared with those of the International Building Code 2009 method; the results demonstrate that the plastic hinges, the interstory drifts and plastic rotation of links are distributed more uniformly in the height of frames designed by the suggested method compared to International Building Code 2009. Copyright © 2012 John Wiley & Sons, Ltd.     

Seismic design and performance analysis of buckling‐restrained braced RC frame structures

Due to the stable hysteretic behavior, buckling‐restrained braces (BRBs) have been increasingly adopted in reinforced concrete (RC) frame structures to develop a dual structural system (BRB‐RCF). This study proposed an alternative strength‐based design approach that decomposes the dual BRB‐RCF system into two independent RC frame and BRB system using the BRB‐carrying story shear ratio. The design of RC frame is performed in an integrated manner by considering the BRB postyielding force demands. Three RC frames with five, 10, and 15 stories were employed as prototype structures, and seven story shear ratios ranging from 0.1 to 0.7 were used to generate a total of 21 structural modes. The material usage, maximum axial compression ratio of columns, and elastic interstory drift ratio were compared for different story shear ratios. Nonlinear dynamic analysis of the BRB‐RCFs subjected to 12 ground motions were carried out. The seismic response including the maximum interstory drift ratio, hysteretic energy dissipation ratio, and actual BRB‐carrying story shear ratio were systematically assessed for different design story shear ratios. Based on the considerations of material usage and seismic performance, it is suggested that the design BRB‐carrying story shear ratio should be in the range of 0.3 to 0.5.     

耦合框架平面外变形钢板装配式屈曲约束支撑#br# 钢筋混凝土框架抗震性能试验研究

为了研究双向地震作用下屈曲约束支撑（Buckling-restrained brace,BRB）钢筋混凝土框架平面内抗震性能以及BRB与钢筋混凝土框架在平面外方向的相互作用,考虑框架平面外变形、节点板平面外刚度和屈曲约束支撑外伸段平面外刚度的影响,对4个钢板装配式屈曲约束支撑钢筋混凝土框架及1个钢筋混凝土空框架进行了平面内拟静力试验研究。研究结果表明：①耦合框架平面外变形的BRB钢筋混凝土框架和无框架平面外变形的BRB钢筋混凝土框架平面内层间剪力与层间位移滞回曲线饱满稳定,具有良好的抗震性能;②框架平面外变形在一定程度上减小了钢板装配式BRB钢筋混凝土框架平面内初始水平刚度和承载力,增大了钢板装配式BRB和节点板平面外变形量;③节点板面外刚度的提高增加了框架节点平面外作用力;④钢板装配式BRB面外刚度的增加能减小自身平面外变形,减小其对钢筋混凝土框架平面外作用力。     

Evaluation of buckling-restrained braced frame seismic performance considering reserve strength

Buckling-restrained braced frame (BRBF) systems are used extensively for resisting lateral forces in high seismic regions of the United States. Numerical and large-scale experimental studies of BRBFs have shown predictable seismic performance with robust ductility and energy dissipation capacity. However, the low post-yield stiffness of buckling-restrained braces (BRBs) may cause BRBFs to exhibit large maximum and residual drifts and allow the formation of soft stories. Thus, reserve strength provided by other elements in the lateral-force-resisting system is critical to improving seismic performance of BRBFs. This reserve strength can be provided in two primary ways: (1) moment-resisting connections within the BRBF and (2) a steel special moment-resisting frame (SMRF) in parallel with the BRBF to create a dual system configuration. These two approaches to providing reserve strength can be used together or separately, leading to a variety of potential system configurations. In addition, special attention must be given to the connections within the BRBF since moment-resisting connections have been observed experimentally to limit drift capacity due to undesirable connection-related failure modes. This paper presents nonlinear dynamic analysis results and evaluates performance of BRBF and BRBF-SMRF systems using moment-resisting and non-moment-resisting beam-column connections within the BRBF. Reserve strength is shown to play a critical role in seismic behavior and performance of BRBFs.     

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。     

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.     

大震下防屈曲支撑钢框架弹塑性位移统计规律

通过600个弹塑性时程分析,统计了防屈曲支撑钢框架结构在罕遇地震作用下的顶层与最大层间弹塑性位移分布规律,为该结构体系的性能化抗震可靠度设计提供了参考。     

A balanced design procedure for special concentrically braced frame connections

Concentrically braced frames (CBFs) are stiff, strong structures that are suitable for resisting large lateral loads. Special CBFs (SCBF) are used for seismic design and are designed and detailed to sustain relatively large inelastic deformations without significant deterioration in resistance. Current AISC Seismic Design Provisions aim to ensure the brace sustains the required inelastic action, but recent research showed that current SCBF design requirements lead to variable seismic performance, unintended failure modes, and limited deformation capacity. To improve the seismic response of SCBFs, a balanced design procedure was proposed. The premise of the design methodology is to balance the primary yield mechanism, brace buckling and yielding, with other, complementary ductile yielding mechanisms, such as gusset plate yielding. This balance process maximizes ductile yielding in the frame thereby maximizing the drift capacity of the frame. Further, the undesirable failure modes are balanced with the yield mechanisms and the preferred failure mode, brace fracture, to ensure that the frame fails in the desired manner. To achieve the objectives of the design methodology namely maximum drift capacity, and adherence to a desired yield and failure hierarchy, rational resistance checks and appropriate balance factors (β factors) are used to balance each yield mechanism and failure mode. These factors were developed, validated, and refined using the measured results from an extensive test program. An SCBF connection design example to illustrate the application of the balanced design method and to demonstrate differences from the current AISC design method is presented in an appendix.     

开孔钢板装配式屈曲约束支撑钢框架抗震性能试验研究

为研究开孔钢板装配式屈曲约束支撑（buckling-restrained brace,BRB）钢框架的抗震性能及框架平面外变形对其抗震性能的影响,对两个相同设计的单层单跨单斜式开孔钢板装配式BRB钢框架分别就是否考虑框架平面外变形情况下进行了拟静力试验,并对相同设计的开孔钢板装配式BRB构件进行了拟静力试验。结果表明：不考虑框架平面外变形和考虑框架平面外变形10mm的开孔钢板装配式BRB钢框架均表现出良好的滞回耗能性能,滞回曲线饱满且基本对称,满足GB 50011—2010《建筑抗震设计规范》最大弹塑性层间位移角1/50的限值要求;框架平面外变形10mm对开孔钢板装配式BRB钢框架平面内抗震性能影响很小,其弹性水平刚度、层间屈服剪力和层间最大剪力受框架平面外变形的影响略为降低,变化范围均在5%以内;框架平面外变形10mm对BRB轴向变形的影响很小,框架中开孔钢板装配式BRB和开孔钢板装配式BRB构件均具有良好的滞回性能,约在1/720层间位移角时先于钢框架进入屈服状态,发挥耗能作用,其滞回曲线饱满,延性良好,累积塑性变形能力系数均大于600,完全满足ANSI /AISC 341-10中要求的大于200的要求。     

钢板装配式屈曲约束支撑RC框架平面#br# 外力学性能试验研究

框架平面外方向的层间侧移在一定程度上影响框架中屈曲约束支撑抗震性能的发挥。为了研究框架平面外的层间侧移作用下,节点板加边肋和屈曲约束支撑端部加强对带屈曲约束支撑钢筋混凝土框架平面外方向力学性能的影响,对3榀安装了钢板装配式屈曲约束支撑的钢筋混凝土框架试件在平面外方向进行拟静力试验。研究了带钢板装配式屈曲约束支撑的钢筋混凝土框架平面外力学性能,节点板加边肋和BRB端部加强对其自身在平面外方向的受力与变形特征。结果表明：钢板装配式屈曲约束支撑对钢筋混凝土框架平面外方向的承载能力影响很小;框架平面外变形引起屈曲约束支撑轴向变形非常微小;在框架平面外层间位侧移作用下,带节点板的BRB呈“C”形的变形模式,节点板加边肋与屈曲约束支撑端部加强的设计能减小BRB轴力对其在平面外方向变形的影响。     

支撑巨型框架-核心筒结构体系抗震性能研究

以深圳平安金融中心为原型结构,提出支撑巨型框架-核心筒结构体系的概念,并以目前超高层常用的巨型框架-核心筒-伸臂桁架结构体系作为参照,开展了结构体系的抗震性能对比研究.研究结果表明,在两种结构体系抗侧刚度相近的工况下,支撑巨型框架-核心筒结构体系的用钢量显著降低.罕遇地震作用下,该结构体系的典型屈服路径为核心筒一巨柱→...     

含有屈曲约束支撑平面框架的抗震性能试验研究

为了研究含有屈曲约束支撑结构的抗震性能,对含有屈曲约束支撑和普通支撑的平面框架进行了试验研究。结合试件破坏现象及试验结果,对屈曲约束支撑的力学性能、破坏机理以及作用效果进行了分析探讨。同时,还对试验过程进行了数值模拟分析。试验及理论分析结果表明:与含普通支撑框架相比,含屈曲约束支撑的框架在提高承载力的同时,还具有更稳定的耗能能力;经过适当的设计,可以使屈曲约束支撑先于主体结构进入弹塑性状态,提高结构的抗震性能。     

Seismic performance of composite moment-resisting frames achieved with sustainable CFST members

The main objective of the research presented in this paper is to study the bending behaviour of Concrete Filled Steel Tube (CFST) columns made with Rubberized Concrete (RuC), and to assess the seismic performance of moment-resisting frames with these structural members. The paper describes an experimental campaign where a total of 36 specimens were tested, resorting to a novel testing setup, aimed at reducing both the preparation time and cost of the test specimens. Different geometrical and material parameters were considered, namely cross-section type, cross-section slenderness, aggregate replacement ratio, axial load level and lateral loading type. The members were tested under both monotonic and cyclic lateral loading, with different levels of applied axial loading. The test results show that the bending behaviour of CFST elements is highly dependent on the steel tube properties and that the type of infill does not have a significant influence on the flexural behaviour of the member. It is also found that Eurocode 4 is conservative in predicting the flexural capacity of the tested specimens. Additionally, it was found that the seismic design of composite momentresisting frames with CFST columns, according to Eurocode 8, not only leads to lighter design solutions but also to enhanced seismic performance in comparison to steel frames.     

基于能量抗震设计方法研究及其在钢支撑框架结构中的应用

介绍了作者近年来关于基于能量抗震设计方法的研究工作。首先,说明了基于能量抗震设计与传统抗震设计方法的关系,指出合理的结构损伤耗能机制控制是实现基于能量抗震设计前提,并据此提出了基于能量抗震设计的框架。随后,介绍了基于能量抗震设计用能量谱,包括单自由度（SDOF）体系总输入能量E _I谱、SDOF体系累积滞回耗能比E_H/E_I谱以及多自由度（MDOF）体系E _I,_MDOF谱与SDOF体系E _I谱的关系,并基于这些谱关系给出了MDOF体系的总累积滞回耗能E_H的确定方法。在此基础上,基于静力弹塑性分析方法给出了结构预期损伤部位累积滞回耗能E_H需求的确定方法,据此结合构件的承载力和变形需求,进行构件层次的基于能量抗震设计。最后,针对某钢支撑框架结构,介绍了所建议的基于能量抗震设计方法的应用。     

Seismic response of a 40‐storey buckling‐restrained braced frame designed for the Los Angeles region

This study utilized nonlinear response history analysis to compare the seismic demand on three variations of a 40‐storey buckling‐restrained braced frame designed for high seismic hazard in the Los Angeles region. The three designs were referred to as a ‘code‐based design’, based on the 2006 International Building Code, a ‘performance‐based design’, based on criteria published by the Los Angeles Tall Building Design Council (LATBSDC) and a ‘performance‐based design plus’, based on newly developed criteria from The Pacific Earthquake Engineering Research Center (PEER). The response history analysis utilized spectrum‐matched ground motions as well as simulated ground motions for the Puente Hills fault. The spectrum‐matched motions were selected from the Next Generation Attenuation of Ground Motions (NGA) database, which is largely composed of recorded motions and scaled to five hazard levels. The simulated ground motions were broadband signals generated from a moment magnitude (M_w) 7.15 scenario rupture of the Puente Hills fault for two near fault regions and exhibit long period energy content that significantly exceeds the uniform hazard spectrum. Structural performance was assessed in terms of exceedance of a safe inter‐storey drift ratio (IDR). It was seen that the simulated ground motions impose higher IDR demands on the structures than the spectrum‐matched NGA ground motions. Furthermore, the number of instances of exceedance of a safe IDR, considered for this study as IDR = 0.03, is substantially higher for the simulated ground motions, pointing to the importance of considering such motions in the collapse prevention of tall buildings on a site‐specific basis. Copyright © 2010 John Wiley & Sons, Ltd.     

防屈曲支撑-钢筋混凝土框架结构基于能量平衡的抗震塑性设计

为确定防屈曲支撑在结构中的布置方式以使结构抗震性能充分发挥,提出了基于能量平衡的防屈曲支撑 钢筋混凝土框架结构抗震塑性设计方法。构建了结构的“强柱弱梁”整体屈服机制,采用侧力比将总结构体系离散为防屈曲支撑体系和纯框架体系,并建立了结构的双线性能力曲线。基于能量平衡方法计算结构的设计基底剪力并分别得到支撑体系和框架体系的设计侧向力,进而完成支撑的截面设计。按照塑性内力分配机制和考虑支撑屈服后性能,计算梁柱构件内力需求。以一幢5层结构为例,分别设计了不同侧力比的14个结构模型,对比了基底剪力、防屈曲支撑面积和梁柱钢筋用量等。通过22条地震波下的弹塑性时程分析,研究了不同侧力比结构的最大层间位移角、屈服机制、楼层剪力比、支撑最大位移延性、累积位移延性和结构残余层间位移角。分析结果表明：所提出的方法能实现结构的预期失效模式,并满足结构的抗震性能要求,并建议设计侧力比选取在0.3~0.5之间。     

Seismic performance of chevron braced frames with shape memory alloy vertical shear link

Chevron braced steel frames with vertical shear link have reliable displacement dependent dampers with sufficient strength and ductility to dissipate energy of strong earthquakes through inelastic mechanisms. In this study, shape memory alloy with its superelastic behavior is utilized as material of vertical shear link to improve the ductility characteristics of the system and decrease residual displacements in the structures due to its self‐centering capability. Nonlinear time‐history, incremental dynamic analysis, and dynamic pushover analysis techniques are used to investigate the behavior of two different four‐ and eight‐story frames with steel vertical shear link (STVL) and shape memory alloy vertical shear link (SMVL) under various earthquake records. The results show that there is a negligible residual displacement in the structures with SMVL, although considerable residual displacements can be observed in the structures with STVL. For instance, when the eight‐story frame is subjected to the Northridge earthquake, a 12‐cm residual displacement is observed in the structures with STVL, whereas the structures with SMVL might experience just 3‐cm residual displacement.