屈曲约束斜撑钢框架弹塑性设计研究

以典型的对称屈曲约束斜撑钢框架为主要研究对象,斜撑框架强度CB以及屈曲约束斜撑的水平力分担率β为主要研究参数,通过二阶非线性静动力分析,对各模型的层间变形、层间力以及塑性能量分布等进行了比较研究。考察了各模型各层的层间位移、层剪力、屈曲约束斜撑的塑性能量分布以及层滞回曲线关系等。结果表明:屈曲约束斜撑水平力分担率β≈30%～60%时,各模型各层的层间静、动力分析结果基本吻合。     

强震下BRBF结构弹塑性静力分析

为考察BRBF结构的层间位移与层剪力的对应关系及塑性铰分布情况,文中以BRBF为研究对象,以屈曲约束支撑的水平力分担率β以及框架强度CB等主要研究参数建立6个模型,通过二阶非线性计算程序,对模型进行弹塑性静力分析。结果表明:屈曲约束支撑的水平力分担率30%～60%的模型的层间变形中低层集中,屈曲约束支撑的水平力分担率90%的模型的层间变形低层集中;模型的层间集中变形以及塑性铰分布情况不受框架强度影响。     

多层屈曲约束支撑钢框架动力响应机理分析

为了研究多层屈曲约束支撑钢框架(BRBF)动力响应机理,采用国际上最常见的BRBF结构形式为研究对象,以屈曲约束支撑BRB水平力分担率β为主要研究参数,进行弹塑性动力二阶非线性分析,探讨了层损伤分布机理以及构件持有性能。结果表明:不同地震波的弹性体系能量谱曲线和结构基本周期对应关系影响多层BRBF结构的最大层间位移反应值和BRB的层最大延性比值;地震波加速度时程的随机性对多层BRBF结构动力损伤分布影响明显,尤其多层BRBF结构抗震设计时有必要考虑地震动瞬时能量影响;BRB对结构减震效果明显,随着BRB水平力分担率β值的增加,BRB最大延性比以及最大累积塑性延性比有相应减小的趋势。     

使用低降伏(屈服)强度阻尼装置之耐震结构设计

于抗弯矩构架之钢骨大楼内设置抗水平力效率高的低降伏(屈服)强度剪力钢板消能装置与挫屈束制(屈曲约束)斜撑构材,除可分担地震侧向力外,还可有效降低结构体之层间侧向位移角;因其具有极佳的韧性消能能力,可消散大部份的地震能量,进而保护抗弯矩构架的梁柱杆件。本文针对钢骨结构内含低降伏强度剪力钢板消能装置与挫屈束制斜撑,以地上十二层、地下三层之钢骨大楼为例,分别说明以低降伏强度剪力钢板消能装置及挫屈束制斜撑各承担大约20％～40％的楼层剪力后,结构在地震历时作用下之各项反应,另外,亦进行以了解在大地震作用下结构构材的能量分布及塑铰形成的情形。     

高β值的多层屈曲约束支撑钢框架结构设计层剪力分布研究

为了研究多层屈曲约束支撑钢框架(Buckling Restrained Braced Frame,简称BRBF)在屈曲约束支撑(Buckling Restrained Brace,简称BRB)分担率β值较高时,层剪力的优化分布,对β值约为0.9的框架振动模型(MF)和质点系振动模型(MS-0、MS-1和MS-2)进行弹塑性时程分析,研究其层剪力、层间位移角、最大倾覆弯矩及支撑固定柱的地震响应。研究结果如下:β值较高时,MF层响应值,中低楼层与质点系振动模型吻合较好,上部楼层接近质点系振动模型MS-1和MS-2。采用静力推倒法进行抗震设计时,修正底部剪力法的F1i和F2i模型分析结果与实际情况更吻合。用底部剪力法设计高β值的BRBF,存在结构柱的地震静力等效值被低估的可能性,有一定程度的安全隐患。在强震作用下,第2振型卓越,上部楼层层反应值较大。     

屈曲约束支撑与黏滞阻尼器的减震效果对比研究

以某钢筋混凝土框架结构工程实例为研究对象,选取与场地条件相匹配的地震动作为激励,在SAP2000程序中计算了该结构在多遇和罕遇地震作用下的非线性动力反应,并在框架结构模型中分别设置屈曲约束支撑和黏滞阻尼器。通过试算确定消能减震装置的参数,使得两种消能减震结构在多遇地震作用下的位移减震率均为40%。在此条件下,对比分析了结构的层间位移角、楼层加速度、基底剪力、柱轴力、塑性铰分布和各层阻尼器的工作状态。分析表明：在多遇地震作用下,屈曲约束支撑增大了结构的加速度响应,而黏滞阻尼器能够减小结构的加速度响应;在罕遇地震作用下,二者均能有效控制楼层的加速度响应,而屈曲约束支撑的位移减震效果更好,但黏滞阻尼器对框架柱内力的减少效果更为显著。     

摇摆防屈曲支撑RC框架抗震性能研究

为研究摇摆防屈曲支撑钢筋混凝土框架抗震性能,利用OpenSees建立8层3跨钢筋混凝土框架(RCF)、防屈曲支撑钢筋混凝土框架(BRBF)与摇摆防屈曲支撑钢筋混凝土框架(RBRBF)有限元模型,并进行弹塑性动力时程分析,从层间位移角、最大顶层位移、最大基底剪力和最大底柱轴力等结构响应角度,研究二维和三维模型分析间关系、...     

带穿层柱钢框架结构受力机理研究

为了研究带穿层柱框架结构的受力机理,将穿层柱高度范围的剩余框架视为子结构,采用广义反弯点法(D值法)确定结构的侧向刚度.考虑穿层柱占比、穿层柱高度对结构侧向刚度比、自振周期、构件内力以及层间位移角的影响,给出了实用的评估方法.通过考虑同层框架柱相互作用的影响,合理确定有侧移框架穿层柱的计算长度系数.分别采用静力弹塑性分析与动力弹塑性时程分析对带穿层柱框架结构进行罕遇地震作用分析.计算结果表明:随着穿层柱数量与穿层柱高度增大,结构的侧向刚度比减小,基本自振周期延长,最大层间位移角增大,柱剪力分配显著变化;穿层柱顶楼层框架梁轴力存在突变,该层楼盖在协调结构变形与内力分配方面具有较大作用,在设计时需要适当加强;在确定有侧移框架穿层柱的计算长度时,可考虑同层框架柱相互作用的影响,对穿层柱的计算长度系数进行修正;穿层柱的弹性刚度较小,在罕遇地震作用下进入塑性较晚,故此其分担的剪力显著增大;随着穿层柱数量减少、穿层柱高度增大,塑性阶段剪力分担率增幅加大.提出的基于穿层柱数量与穿越层数的地震力放大拟合计算式,可用于穿层柱塑性阶段剪力占比放大倍数估算.     

不同布置方案屈曲约束支撑-钢框架体系静力弹塑性分析

基于刚度比的屈曲约束支撑框架体系设计方法,设计了两种不同支撑布置方案框架体系与空框架对比,应用有限元软件SAP 2000对各体系进行静力弹塑性(Pushover)分析,研究其在8度罕遇地震下的塑性铰分布、层间位移角、连接滞回耗能以及框架柱轴力等。研究结果表明:各体系的最大层间位移角小于弹塑性位移角限值1/50。屈曲约束支撑能抑制体系的塑性铰发展,且布置数量越多效果越明显,但并未改变体系的薄弱层分布;同时,连接滞回耗能占比不低于20%,体现出屈曲约束支撑良好的耗能能力。在此基础上,提出一种改进的错列布置方式的屈曲约束支撑框架体系,能改善底层柱轴力集中现象,支撑用量减少了16.7%,且其抗震能力无明显改变。     

地震波特性对形状记忆合金自复位支撑框架响应影响

地震作用下屈曲约束支撑框架具有较好的消能减震效果,但是支撑进入塑性后残余变形较大,影响了框架震后可修复。将形状记忆合金(SMA)与屈曲约束支撑(BRB)组合,形成了SMA自复位屈曲约束支撑(SMA-SCBRB)。为了对比普通屈曲约束支撑(BRB框架)和SMA自复位屈曲约束支撑框架(SMA-SCBRB框架)的动力特性,基于已开展的足尺振动台试验模型,选用了6条近场地震波和4条远场地震波作为地震动输入,对比两类框架的动力反应。结果表明:BRB框架结构具有较好的消能减震效果,近场地震波作用下,BRB框架的顶点位移、顶点残余位移、层间位移角和层间残余位移角均大于远场地震波作用下的结构反应;将框架中的BRB按照"等屈服力原则"替换为SMA-SCBRB,近场和远场地震波作用下BRB框架和SMA-SCBRB框架有着相近的顶点位移和层间位移角,能够保证SMA-SCBRB通过轴向变形充分耗能;BRB框架具有较大的顶点残余位移和层间残余位移角,近场地震波作用下残余变形更大;而相应的SMA-SCBRB框架的残余变形降低,特别是下部楼层降低得更为显著,且SMA-SCBRB框架各层的层间残余位移角相近,对结构震后修复更为有利。     

A comparison of dynamic nonlinear behavior of ordinary and buckling restrained braced frames subjected to strong ground motion

In this paper nonlinear dynamic analyses of 4‐ to 12‐story frames with two types of bracing behavior are performed. In the first series of analyses, the bracing post‐buckling behavior is modeled using a Jain‐phenomenological model. In this model bracing buckled against compressive loading and yielded when subjected to tensile loading. In the second series, buckling restrained brace frames subjected to strong ground motion have been analyzed using elements with a bilinear behavior. The results in terms of story drifts, story shears, story shear versus drift hysteresis behavior and plastic hinge locations were compared. By comparing the response of the frame with the buckling restrained brace and the ordinary brace, better performance was observed for the buckling restrained braced frames. Copyright © 2007 John Wiley & Sons, Ltd.     

双阶屈服屈曲约束支撑框架小震参数分析

为了弥补常规屈曲约束支撑在多遇地震作用下处于弹性状态,不能发挥消能减震作用的不足,提出了一种将金属套管阻尼器与屈曲约束支撑组合形成的双阶屈服屈曲约束支撑,经试验验证其具有良好、稳定的小震及中大震下的滞回特性。在小震作用下,金属套管阻尼器屈服消能,屈曲约束芯板保持弹性承载。借助有限元软件ETABS建立了一系列双阶屈服屈曲约束支撑框架模型,通过改变支撑与框架刚度比、阻尼器与芯板的轴向刚度关系以及套管阻尼器的屈服比例,对各模型进行小震作用下的动力弹塑性分析,将各模型基底剪力和最大层间位移角与相应的常规屈曲约束支撑框架的分析结果进行对比。结果表明:双阶屈服屈曲约束支撑与支撑芯板的轴向弹性刚度比取2左右,阻尼器屈服比例取0.3左右时,可取得较好的减震效果; 双阶屈服屈曲约束支撑的参数取值改变,对降低结构地震响应的影响趋势不因支撑与框架刚度比不同而改变; 当支撑刚度贡献较大时,相较常规屈曲约束支撑,双阶屈服屈曲约束支撑的设置能降低结构的层间位移角,若要同时降低基底剪力,阻尼器屈服比例不宜高于0.3。     

Bracing configuration and seismic performance of reinforced concrete frame with brace

Brace has been used to improve structural seismic performance in reinforced concrete (hereafter called RC) frame extensively. However, the reasonable bracing configurations were not highlighted. And the brace buckling was not considered. Bracing configurations and seismic performance of RC frame with brace are studied in this paper. First, optimized bracing configurations of entire structures and 1‐story 1‐span structures are derived by topology optimization using truss‐like material model. Next, the structure models are simulated in OpenSees. Moreover, different bracing configurations are employed. Last, seismic performance and seismic response of RC frame structures with brace are discussed using static nonlinear analysis and dynamic time–history analysis, and brace buckling is considered. The numerical results indicate that more details for manufacturing or constructing can be presented by bracing configuration using truss‐like model. Further, the increase of structural strength and stiffness is more advisable in bracing configuration using topology optimization (hereafter called TPB), which corresponds to optimized result using entire structure than other configurations. The optimized bracing configuration based on 1‐story 1‐span structure is also beneficial within the prescribed conditions. Moreover, the brace buckling can decrease both strength and stiffness, and the buckling can also aggravate the damage extent than the brace without buckling.     

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.     

两边连接屈曲约束钢板剪力墙受力机理与等效支撑模型

采用理论分析和有限元方法,针对两边连接屈曲约束钢板剪力墙的受力机理和传力规律进行研究。提出了钢板墙边缘约束区的概念并确定了边缘约束区的宽度,分析了钢板墙的屈服形状、钢板墙内各部分应力流的分布规律和钢板墙与梁连接处的受力特点等。在此基础上提出了两边连接屈曲约束钢板剪力墙等效支撑模型,对不同尺寸、不同层数的框架 屈曲约束钢板剪力墙结构和框架 等效支撑结构在水平荷载作用下的力学性能进行分析,并对两种结构的荷载 位移曲线进行了对比。分析表明,所提出的等效支撑模型在结构刚度和承载力方面具有较好的准确性,无论是单调加载还是反复加载均能准确地模拟两边连接屈曲约束钢板剪力墙结构的受力行为。     

Cyclic responses of three 2-story seismic concentrically braced frames

Three full scale two-story steel concentrically braced frames (CBFs) were tested at the National Center for Research on Earthquake Engineering (NCREE) in Taipei. The specimen is a single bay with the braces arranged in a two-story X-brace configuration. The main differences among the three tests are the brace types (hollow structural or wide-flange section) and the design criteria adopted for the gusset plate connections. Results of these three tests confirm that the two-story X-shape steel CBFs all have rather good energy dissipation characteristics up to a story drift of about 0.03 radians under the cyclically increasing lateral displacements. Severe brace local buckling and out-of-plane displacements were observed during each test. Tests confirm that both the 2t-linear and 8t-elliptical designs of the gusset plate connection provide satisfactory ductility for the steel CBF. Hollow structural section (HSS) braces fractured at a story drift smaller than that found using wide flange sections. The nonlinear fine element method (FEM) program ABAQUS was used to simulate the responses of the specimen. The base shear versus the story drift relationships obtained from the tests and the FEM analytical results are quite agreeable in various levels of lateral frame displacement. The analytical results confirm that the severe out-of-plane buckling of the braces can be accurately simulated. FEM analyses also illustrate that the steel moment resisting frame takes about 40% story shear when the inter-story drift is greater than 0.02 radians.     

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。     

设置屈曲约束支撑的斜交网筒结构延性有限元分析

斜交网筒结构具有较大的抗侧刚度,但其延性较差,通过设置屈曲约束支撑可改善斜交网筒结构延性。以30层的斜交网筒结构模型为研究对象,分别对普通斜交网筒结构和设置屈曲约束支撑斜交网筒结构进行静力弹塑性推覆（Pushover）分析。结果表明：屈曲约束支撑可有效改善斜交网筒结构延性。此外,对立面中部、立面角部、底部楼层、上部楼层共4种局部区域布置屈曲约束支撑的方案进行了结构延性分析。局部设置屈曲约束支撑斜交网筒结构的设计应确保斜柱处于弹性工作状态,屈曲约束支撑率先进入塑性耗能状态。建议采用立面中部布置屈曲约束支撑的方案,可实现在保证结构受剪承载力的前提下,较好地改善斜交网筒结构的延性,避免结构发生脆性破坏。     

Cyclic responses of three 2-story seismic concentrically braced frames

Abstract Three full scale two-story steel concentrically braced frames (CBFs) were tested at the National Center for Research on Earthquake Engineering (NCREE) in Taipei. The specimen is a single bay with the braces arranged in a two-story X-brace configuration. The main differences among the three tests are the brace types (hollow structural or wide-flange section) and the design criteria adopted for the gusset plate connections. Results of these three tests confirm that the two-story X-shape steel CBFs all have rather good energy dissipation characteristics up to a story drift of about 0.03 radians under the cyclically increasing lateral displacements. Severe brace local buckling and out-of-plane displacements were observed during each test. Tests confirm that both the 2t-linear and 8t-elliptical designs of the gusset plate connection provide satisfactory ductility for the steel CBF. Hollow structural section (HSS) braces fractured at a story drift smaller than that found using wide flange sections. The nonlinear fine element method (FEM) program ABAQUS was used to simulate the responses of the specimen. The base shear versus the story drift relationships obtained from the tests and the FEM analytical results are quite agreeable in various levels of lateral frame displacement. The analytical results confirm that the severe out-of-plane buckling of the braces can be accurately simulated. FEM analyses also illustrate that the steel moment resisting frame takes about 40% story shear when the inter-story drift is greater than 0.02 radians.