Seismic testing and numerical analysis of Y‐shaped eccentrically braced frame made of high‐strength steel

In eccentrically braced frame made of high‐strength steel (HSS‐EBF), link and brace are made from conventional steel whereas other structural members use high‐strength steel. Using HSS for beams and columns in EBF can reduce steel consumption and increase economic efficiency. In this paper, one shake table test of a 1:2 scaled three‐story Y‐shaped HSS‐EBF (Y‐HSS‐EBF) specimen was carried out to study its seismic behavior underground motions with different peak ground accelerations. The dynamic properties, base shear force, displacement, and strain responses of the specimen were obtained from this test. In addition, the finite element models of two 10‐story Y‐HSS‐EBF buildings and one 10‐story conventional Y‐EBF building were evaluated for seismic effects. Nonlinear pushover and dynamic analyses were conducted to compare their seismic performance and economy. The results indicated that the specimen exhibited sufficient lateral stiffness and safety but suffered some localized damages. During the high seismic intensity earthquakes, the links of the test specimen were in inelastic to dissipate the earthquake energy, whereas other structural members remained in the elastic state. Under the same design conditions, Y‐HSS‐EBF used less steel than that of conventional Y‐EBF, which could reduce the amount of steel used in Y‐HSS‐EBF. The Y‐HSS‐EBF is a safe, dual system with reliable seismic performance.     

Y形偏心支撑高强钢框架结构抗震性能

在Y形偏心支撑高强钢框架结构抗震性振动台试验的基础上,建立了试验试件的有限元模型,并验证了分析的正确性。设计了一个9层的Y形偏心支撑高强钢框架结构,以耗能梁段长度、耗能梁段腹板高厚比、高跨比为参数,对9层结构进行了非线性动力时程分析,研究了以上参数对结构抗震性能的影响。研究结果表明,改变耗能梁段长度、高跨比对结构层间侧移、耗能梁段性能、框架柱弯矩、耗能能力均有不同程度的影响,对框架柱轴力、基底剪力无显著影响;改变耗能梁段腹板高厚比对结构耗能能力有影响,对结构层间侧移、耗能梁段性能、框架柱受力、基底剪力无显著影响,并给出了相关设计建议。     

Fundamental periods of steel eccentrically braced frames

This paper describes formulation of a hand method that can be used to estimate the computed fundamental periods of vibration of building structures in general and steel eccentrically braced frames (EBFs) in particular. The developed method uses the Rayleigh's method as a basis and utilizes the roof drift ratio (RD_R) under seismic forces as a parameter. To obtain RD_R, more than 4000 EBFs were designed by considering the seismic hazard, number of stories, braced bay width and link length to bay width ratio as prime variables. A model was developed to estimate RD_R, which depends on the rigid plastic deformation mechanism for a typical EBF. The method was verified using design data produced as a part of this work as well as data published in literature. The verifications indicate that the proposed formulation is capable of providing acceptable estimates of the computed period. When compared with existing empirical period–height relationships, the proposed formulation offers closer estimates with reduced scatter. The method was further refined to derive new period–height relationships for two different seismicity regions. The accuracy of the relationship for high seismic regions was verified using measured periods of EBF buildings. Copyright © 2014 John Wiley & Sons, Ltd.     

3种偏心支撑钢框架的塑性设计方法

偏心支撑钢框架是在中心支撑钢框架的基础上发展起来的一种新型结构体系,它能够有效改善钢框架在大震作用下的抗震性能。本文基于已有耗能梁段的塑性设计模型,考虑钢材的应变硬化效应影响,提出了一种改进的偏心支撑耗能梁段塑性模型,并基于此模型对不同形式的偏心支撑钢框架在弯矩、剪力共同作用下的屈服模型进行了研究,推导出其塑性设计公式。     

两种偏心支撑钢框架受力性能对比分析

建立了空间Y型与K型偏心支撑钢框架有限元模型,对两种模型框架进行了单向加载和循环加载试验,对比分析了两种空间偏心支撑框架的屈服强度、极限承载力、侧向刚度、延性和耗能能力等方面受力性能的差异,为工程设计提供参考。     

Y形偏心支撑-高强钢框架结构抗震性能试验研究

为研究Y形偏心支撑-高强钢框架结构抗震性能,在已完成的1∶2缩尺3层模型结构振动台试验的基础上,重新设计了耗能梁段,并对该结构再次进行振动台试验。试验中选取El Centro波、Taft波和兰州波作为地震动输入并考虑7度多遇到9度罕遇的地震水准,分析了结构在水平地震作用下的动力特性、加速度响应、位移响应、应变响应、剪力分布等,并与已有试验结果进行了对比。通过ABAQUS建立了有限元分析模型,与试验结果进行对比。结果表明：该结构在多遇地震作用下处于弹性状态,在罕遇地震作用下表现为耗能梁段的局部破坏;耗能梁段破坏后,结构刚度大幅下降,但未发生倒塌;在多遇地震和罕遇地震作用下,结构的最大层间位移角满足抗震规范层间位移角限值的相关要求;在罕遇地震作用下,耗能梁段进入塑性状态而进行耗能,其他构件仍保持弹性状态;所建立的有限元模型可以有效模拟振动台试验结果。     

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.     

高强钢组合K形偏心支撑框架抗震性能对比分析

为研究不同强度组合的高强钢组合K形偏心支撑框架结构的抗震性能,设计了一组不同强度(Q345、Q460、Q690钢材)组合的5层K形偏心支撑框架结构算例Q345-5、Q460-5和算例Q690-5,选取10条地震动记录对其进行动力时程分析,得到各算例在不同水准地震作用下的耗能梁段转角和层间位移角。研究表明:8度罕遇地震作用下,高强钢组合K形偏心支撑框架的层间位移角比传统K形偏心支撑钢框架大,各算例耗能梁段全部进入塑性变形阶段;塑性层间位移角到达规范限值时,算例Q460-5框架梁开始进入塑性变形阶段,算例Q690-5框架柱、框架梁和支撑均处于弹性变形阶段,还可以承受更大的地震作用;达到定义的极限状态时,与传统偏心支撑钢框架相比,算例Q460-5能够承受的地震作用和耗能梁段转角更小;算例Q690-5承受的地震作用和耗能梁段转角更大。     

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.     

改进加盖板法用于D型偏心支撑结构的抗震性能试验研究

提出一种新型剪切型耗能梁段与柱连接节点——改进加盖板方案,在满足梁端抗弯、抗剪承载力的同时,放松对耗能梁段的约束,使其充分发展剪切塑性变形,耗散更多的地震能量。采用1∶3缩尺模型,将该新型方案用于D型偏心支撑结构中,与传统的D型偏心支撑结构进行了对比试验,结果表明,采用改进加盖板方案的单斜杆偏心支撑结构具有很好的抗侧移刚度和变形能力,并具有足够的抗侧移能力;可以将耗能梁段从柱边移开,从而允许耗能梁段有较大转动,耗散更多的地震能量。同时也给出了改进加盖板方案的设计方法。     

多层高强钢组合Y形偏心支撑钢框架抗震性能试验研究

为研究高强钢组合Y形偏心支撑钢框架结构的抗震性能,进行了一个1∶2缩尺模型的三层结构试件的低周往复加载试验,从结构的承载能力、刚度退化、位移延性、耗能能力及破坏模式等方面评价了结构的抗震性能,试验采用三质点倒三角形比例加载。研究结果表明：高强钢组合Y形偏心支撑结构具有较高的承载能力、较好的位移延性和耗能能力,屈服强度较低的耗能连梁的弹塑性变形耗散了大部分地震能量,而高强钢非耗能构件基本处于弹性受力状态,保证了极限状态下结构的完整性。框架梁与耗能连梁连接节点处受力复杂、应力集中严重,加之楼板对框架梁的约束,该节点处变形较大,使得试件最终在此位置破坏。     

基于多目标性能的高强钢组合K形偏心支撑框架塑性设计方法研究

高强钢组合K形偏心支撑框架结构(K-HSS-EBFs)作为一种典型的双重抗侧力体系,可以实现结构抗震设计中多道设防的目标。针对传统K-HSS-EBFs性能设计方法中无法考虑多水准抗震设防目标以及支撑-框架体系剪力分配的问题,对基于多目标性能的K-HSS-EBFs塑性设计方法进行修正。通过考虑结构后屈服刚度变化得到K-HSS-EBFs的三折线能力曲线,采用能量平衡原理计算支撑-框架体系在不同性能目标下的弹性和弹塑性剪力分配,从而对结构进行弹塑性设计。采用修正的设计方法设计了一个6层的K-HSS-EBFs结构算例,建立OpenSees有限元模型,选取20条地震波对其进行不同强度地震作用下的弹塑性时程分析。结果表明：采用所提设计方法设计的K-HSS-EBFs实现了结构预期的破坏模式以及不同强度地震作用下的位移延性需求和剪力分布模式;从多遇地震到罕遇地震,算例模型中框架跨所承担的基底剪力占比由29%提高到44%,满足GB 50011—2010《建筑抗震设计规范》中对于多道设防体系内力重分布后的结构总基底剪力分配要求。     

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。     

V型偏心支撑钢框架抗震性能非线性时程分析

针对V型偏心支撑钢框架的不同耗能梁段长度,运用有限元分析软件SAP2000对相应的算例进行非线性时程分析。通过对构件内力、节点位移等计算结果的分析,并与D型和K型偏心支撑钢框架非线性时程分析的结果进行比较,得到了一些结论,以供工程设计人员参考。     

D型偏心支撑钢框架抗震性能非线性时程分析

针对D型偏心支撑钢框架的不同耗能梁段长度,运用有限元分析软件SAP2000对相应的算例进行非线性时程分析。通过对构件内力、节点位移等计算结果的分析得到了一些结论,以供工程设计人员参考。     

Damage‐controlled performance‐based design optimization of steel moment frames

In the present paper, performance‐based design of steel moment‐resisting frames (SMRFs) is implemented to minimize total cost of the structures. The total cost is summation of the initial construction cost and the seismic damage cost in operational lifetime of the structures subjected to seismic loading. In order to evaluate the seismic damage cost, Park–Ang damage index (DI), as one of the most realistic measures of structural seismic damage, is utilized. To calculate the DI, nonlinear time‐history response of the structure needs to be evaluated during the optimization process. As the computational burden of the process is very high, neural network techniques are utilized to predict the required nonlinear time‐history structural responses. As the design constraints, besides the drift checks at immediate occupancy and collapse prevention performance levels, the global DI is also checked at collapse prevention level to control the amount of seismic damage. In order to achieve the optimization task, a sequential enhanced colliding bodies optimization II is proposed. Numerical studies are conducted to demonstrate the efficiency of the proposed methodology involving 2 illustrative examples of a 6‐story SMRF and a 12‐story SMRF.     

基于屈服点谱法的中心支撑钢框架抗震性态评估

屈服点谱(Yield Point Spectra,YPS)是以位移-加速度表述的反应谱形式。YPS可以用于对现有结构进行抗震评估,确定结构在给定地震作用下的峰值位移和延性。本文按照我国设计规范分别设计了6层、9层、12层3个人字形中心支撑钢框架结构,利用YPS对3个结构进行非线性静力分析,得到结构在设防地震和罕遇地震下的峰值位移和层间位移角,并与SAP2000动力时程分析得到的结果进行对比,评估人字形中心支撑钢框架在设防地震和罕遇地震下的抗震性态,评价了YPS方法用于中心支撑钢框架抗震性态评估的可靠性。     

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.     

Design and seismic response of tall chevron panel buckling‐restrained braced steel frames

The numerical analysis of the seismic performance for tall chevron panel buckling‐restrained braced steel frames (PBRBFs) under small and strong earthquake excitations has been carried out to investigate a capacity design procedure for chevron PBRBFs and to examine the effects of axial strength distribution of braces along the height of buildings, vertical supports of braces for the braced beams and the overstrength of braces on the seismic response of PBRBFs. It revealed that the chevron braces that remained elastic can actually provide the vertical supports for the braced beams. Under severe earthquake excitations, the vertical supports deteriorated greatly after braces yielding. The PBRBFs designed by omitting vertical supports of braces for the braced beams and considering the overstrength of braces exhibited superior performance with smaller plastic deformations for braced beams and reduction in ductility demands for panel buckling‐restrained braces (PBRBs) as compared with the others. The distribution of yielding for PBRBs in 10‐story buildings verified that the participation from the higher modes is not very remarkable and that the capacity design based on the first‐mode response can be considered for multistory PBRBFs. Moreover, on the basis of the analysis results of the 30‐story PBRBF, the participation of the higher modes should be taken into account for high‐rise PBRBFs. Copyright © 2011 John Wiley & Sons, Ltd.     

基于增量动力分析的梁贯通式支撑钢框架地震易损性研究

为了得到梁贯通式支撑钢框架节点刚度及承载力设计方法,基于增量动力分析(IDA)方法,研究了节点性能对多层梁贯通式支撑钢框架地震易损性的影响,得到了不同节点刚度和承载力设置下四种模型(刚接、全强度半刚接、半强度半刚接和铰接模型)的易损性曲线,定量评价了各模型超越各极限状态的概率和倒塌储备系数.研究结果表明:无论节点刚度和...