Experimental evaluation of the seismic performance of steel MRFs with compressed elastomer dampers using large-scale real-time hybrid simulation

Real-time hybrid simulation combines experimental testing and numerical simulation, and thus is a viable experimental technique for evaluating the effectiveness of supplemental damping devices for seismic hazard mitigation. This paper presents an experimental program based on the use of the real-time hybrid simulation method to verify the performance-based seismic design of a two story, four-bay steel moment resisting frame (MRF) equipped with compressed elastomer dampers. The laboratory specimens, referred to as experimental substructures, are two individual compressed elastomer dampers with the remainder of the building modeled as an analytical substructure. The proposed experimental technique enables an ensemble of ground motions to be applied to the building, resulting in various levels of damage, without the need to repair the experimental substructures, since the damage will be within the analytical substructure. Statistical experimental response results incorporating the ground motion variability show that a steel MRF with compressed elastomer dampers can be designed to perform better than conventional steel special moment resisting frames (SMRFs), even when the MRF with dampers is significantly lighter in weight than the conventional MRF.     

Performance assessment of innovative seismic resilient steel knee braced frame

Buckling restrained knee braced truss moment frame (BRKBTMF) is a novel and innovative steel structural system that utilizes the advantages of long-span trusses and dedicated structural fuses for seismic applications. Steel trusses are very economical and effective in spanning large distance. However, conventional steel trusses are typically not suitable for seismic application, due to its lack of ductility and poor energy dissipation capacity. BRKBTMF utilizes buckling restrained braces (BRBs) as the designated structural fuses to dissipate the sudden surge of earthquake energy. This allows the BRKBTMF to economically and efficiently create large span structural systems for seismic applications. In this paper, a prototype BRKBTMF office building located in Berkeley, California, USA, was designed using performance-based plastic design procedure. The seismic performance of the prototype building was assessed using the state-of-the-art finite element software, OpenSees. Detailed BRB hysteresis and advanced element removal technique was implemented. The modeling approach allows the simulation for the force-deformation response of the BRB and the force redistribution within the system after the BRBs fracture. The developed finite element model was analyzed using incremental dynamic analysis approach to quantify the seismic performance of BRKBTMF. The results show BRKBTMF has excellent seismic performance with well controlled structural responses and resistance against collapse. In addition, life cycle repair cost of BRKBTMF was assessed using the next-generation performance-based earthquake engineering framework. The results confirm that BRKBTMF can effectively control the structural and non-structural component damages and minimize the repair costs of the structure under different ranges of earthquake shaking intensities. This studies conclude that BRKBTMF is a viable and effective seismic force resisting system.     

Energy appproach in peformance‐based seismic design of steel moment resisting frames for basic safety objective

This study presents an energy approach to the performance‐based seismic design of steel moment resisting frames for the basic safety objective. The seismic demand is expressed in terms of hysteresis energy and its distribution along the height of the frame, based on an associated study. The resistance of a steel moment‐resisting frame to such demand is presented in the form of energy dissipation capacities of critical members, based on the previous experimental studies on full‐scale moment‐connections. An energy‐based design methodology is proposed for performance‐based earthquake resistant design. The proposed design method is examined using design examples and the results are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Optimized design procedure for coupling panels in steel plate shear walls

Coupling beams have had a widespread application as performance enhancing devices within concrete structures and more recently also in steel structures. However, the conventional coupling beams are not so efficient in coupling distant walls. In this paper, a novel form of coupling members, namely, coupling panels is proposed and, then, the application for a nine‐story building is investigated. Coupling panels are steel plates which are exerted in the intermediate spans between adjacent shear walls and act as a mega‐coupling beam. First, a verified finite element model is constructed to demonstrate coupling panel behavior along with its global structural mechanism. Subsequently, a nine story building is designed and retrofitted as a new and existing building, using coupling panels. Moreover, an innovative optimization algorithm is proposed in order to achieve the best plate configuration to improve the structural performance using Nonlinear Static Analysis, Modal Pushover Analysis and Time History Analysis and the corresponding results are compared. In summary, it is shown that coupling panels can considerably control structural deformation demands toward a uniform pattern and reduce demands of main shear walls. The optimized design method also leads to a more economical design in comparison with force‐based design approaches. In addition, the proposed coupling panels are shown to be significantly effective, regarding to energy dissipation during earthquakes, and can enhance the structural resiliency. Copyright © 2016 John Wiley & Sons, Ltd.     

水平双向地震作用下薄壁方形截面钢桥墩#br# 抗震性能试验及实用算法研究

钢板局部失稳破坏是钢桥墩结构典型的地震失效模式之一,但目前仍缺乏既能考虑局部失稳影响,又可方便用于工程设计的结构地震反应计算方法。通过对2个薄壁方形截面钢桥墩试件施加沿斜向的水平反复荷载,研究结构的地震破坏形式和抗震性能;在钢材修正双曲面滞回模型的基础上,通过对结构参数分析结果的数据拟合,建立考虑钢板局部失稳影响的方形截面钢桥墩纤维模型算法。结果表明：薄壁方形截面钢桥墩结构在水平双向地震作用下,首先会发生墩底钢板局部失稳,在荷载达到最高点后墩底焊缝处出现超低周疲劳破坏,在两种地震破坏的共同作用下结构承载力迅速下降;通过与试验结果的对比,验证结构地震有效损伤域Ld内的纤维单元采用等效滞回模型能准确反映钢板的局部失稳效应,为工程设计提供一种高精度的实用计算方法。     

Experimental analysis of seismic resistant composite steel frames with dissipative devices

This article presents the results of the experimental research performed at Politecnico di Milano, within the project Fuseis. The research project aims at developing innovative types of seismic resistant composite steel frames with dissipative fuses. In case of strong seismic events, damage will concentrate only in these fuses, without observing any significant damage in the structural elements such as steel beams, columns and reinforced concrete slab of the structure. After the seismic event, the repair work will be limited only to replacing the fuses. Four full scale tests are implemented in order to evaluate the performance of a composite steel frame with fuse devices under seismic actions in terms of moment rotation behavior of the joints, global energy dissipation, storey drift and frame stability.     

循环荷载作用下空腹式交错桁架钢结构抗震性能试验研究

为研究空腹式交错桁架结构体系的抗震性能,进行了1个5层空腹式交错桁架钢结构1/3缩尺模型试验,研究了该结构体系在循环荷载作用下的抗震性能和破坏机理,并从滞回性能、刚度退化、结构延性、耗能能力及破坏模式等方面评价该结构体系的抗震性能。试验及分析结果表明:该结构具有承载能力高、变形能力较强、耗能能力好等优点,但其侧向刚度偏弱,各层层间位移延性角差别较大,结构沿高度方向侧向刚度分布不均匀。应力测试结果表明,该结构塑性铰开始形成于桁架腹杆,然后是桁架弦杆,最后在柱中形成塑性铰,地震能量主要通过桁架耗散,其破坏属于梁铰机制,满足强柱弱梁的抗震要求。     

Analytical Model for Viscous Wall Dampers

By now, many civil engineering researchers have extensively studied the application of earthquake energy dissipation systems in seismic‐resistant buildings. Earthquake energy dissipation systems play an important role in enhancing the sustainability of structures against seismic excitation. Frame buildings are strengthened by installing damper devices as supplemental structural members. This article presents the finite‐element‐based development of an analytical model for a viscous wall damper (VWD) device, an alternative to other earthquake energy dissipation systems, which can diminish the effect of earthquakes on structures and improve the seismic performance of multistory buildings subjected to ground motion. The constitutive law of VWDs has been formulated and integrated to develop a finite element model of VWD compatible with the reinforced concrete (RC) structure analytical model. Then, the finite element algorithm has been developed for inelastic analysis of RC buildings equipped with VWD devices capable of detecting damage to both structural members and damper connections under dynamic loading. Based on the developed system, the special finite element program was codified and verified by applying it to a real model of a RC building with supplementary VWD devices. Influence of VWDs on seismic performance of the RC building during earthquake excitation was evaluated. The proposed analytical model for VWD is verified by using experimental test data and analysis result proved that this energy dissipation system succeeds by substantially diminishing and dissipating a structure's induced seismic responses. Also the parametric study indicated that the damping coefficient is very effective on performance of VWD.     

Optimization layout of viscous dampers and its application in retrofitting of a high-rise steel structure

阻尼器优化布置是结构减震设计过程中的重要环节，通常需要通过多次动力响应计算来完成。为此，提出了一种通过结构静力分析确定阻尼器合理布置位置的方法，并能够快速计算出优化方案的附加阻尼比。将该方法应用于一栋位于日本东京都新宿区29层钢结构建筑的减震加固设计中，分析了该建筑的强震观测系统在日本“311地震”中采集到的部分楼层加速度时程数据，并基于分析结果验证了所建立的非线性数值分析模型的可靠性。采用所提方法对结构进行减震加固，得到双向共64个阻尼器的优化布置方案及其附加阻尼比，并通过动力方法对结果进行了验证。同时针对长周期及长持时特性的地震波，对减震结构进行动力弹塑性时程分析，评估其抗震性能。分析结果表明：减震优化方案的减震效果明显，结构整体地震反应和构件损伤较非减震方案都大大减小；减震优化方案有效改善了高层钢结构楼层变形不均匀的情况，层间位移角均满足小于1/100的性能要求；通过减震优化后大部分钢支撑和钢梁的塑性率都降低至小于1。     

黏滞阻尼器的优化布置及其在高层钢结构加固中的应用

阻尼器优化布置是结构减震设计过程中的重要环节,通常需要通过多次动力响应计算来完成。为此,提出了一种通过结构静力分析确定阻尼器合理布置位置的方法,并能够快速计算出优化方案的附加阻尼比。将该方法应用于一栋位于日本东京都新宿区29层钢结构建筑的减震加固设计中,分析了该建筑的强震观测系统在日本“311地震”中采集到的部分楼层加速度时程数据,并基于分析结果验证了所建立的非线性数值分析模型的可靠性。采用所提方法对结构进行减震加固,得到双向共64个阻尼器的优化布置方案及其附加阻尼比,并通过动力方法对结果进行了验证。同时针对长周期及长持时特性的地震波,对减震结构进行动力弹塑性时程分析,评估其抗震性能。分析结果表明：减震优化方案的减震效果明显,结构整体地震反应和构件损伤较非减震方案都大大减小;减震优化方案有效改善了高层钢结构楼层变形不均匀的情况,层间位移角均满足小于1/100的性能要求;通过减震优化后大部分钢支撑和钢梁的塑性率都降低至小于1。     

Seismic analysis of steel structures considering damage cumulation

The research on the development of a reliable analytical model for seismic analysis of steel structures is presented. The non-linear damage cumulation hysteretic model incorporating the deterioration of stiffness, strength and strain hardening for structural steel is proposed and validated. The complete loading history, energy dissipation and the effect of the maximum plastic strain are taken into account in the model. The constants in the model are determined from regression analysis of experimental results of simple standard tensile and cyclic tests. Finite element formulations for beam and structural solid element considering the damage cumulation are derived. A computer program capable of calculating the hysteretic model of steel members, predicting the damage state and crack initiation, and carrying out non-linear time history seismic analysis of steel structures is developed. Solutions obtained from the model are in good agreement with experimental results. It was demonstrated that the damage cumulation effect is considerable and important in structural seismic analysis.     

方钢管活性粉末混凝土柱地震损伤模型研究

为研究方钢管活性粉末混凝土(RPC)柱在水平低周往复荷载作用下的抗震性能和地震损伤模型,利用ABAQUS有限元软件建立了125根不同参数(含钢率、轴压比及长细比)的方钢管RPC柱模型,对其滞回曲线、骨架曲线、延性及耗能能力进行分析。参考Park损伤模型和付国有效耗能假设,提出一种基于变形和有效累积滞回耗能的双参数损伤模型,非线性拟合得到损伤参数α=0.851和β=-0.508。研究结果表明:滞回曲线的形状规则且饱满,说明方钢管RPC柱具有良好的变形能力和耗能能力,有限元分析结果与试验结果吻合较好,验证了方钢管RPC柱模型建立的正确性; 将方钢管RPC柱试件的变形和有效累积滞回耗能结果代入损伤模型计算的试件损伤变量D值均接近于1,试件最终破坏形态及其损伤变量D值与损伤评估中《建(构)筑物地震破坏等级划分》(GB/T 24335—2009)规定的地震破坏等级中的破坏现象及其所对应的损伤变量D值基本一致,说明该损伤模型能较好地反映方钢管RPC柱的地震损伤状态。     

Energy-based design optimization of steel building frameworks using nonlinear response history analysis

Presented in this paper is a design optimization method for steel building frameworks subjected to seismic loading using a nonlinear response history analysis procedure. Minimum weight, minimum seismic input energy and maximum hysteretic energy of fuse members are identified as the three design objectives. Design constraints include the limits on inter-story drift and plastic rotation of member sections. The design optimization method employs a multi-objective genetic algorithm to search for optimal member section sizes from among commercially available steel section shapes. The design method is illustrated for a moment-resisting steel frame of a three-story building. It is concluded the proposed optimization methodology is an effective and efficient application of the capacity-design principle to building frameworks under earthquake loading.     

Seismic performance of steel MRF building with nonlinear viscous dampers

This paper presents an experimental study of the seismic response of a 0.6-scale three-story seismicresistant building structure consisting of a moment resisting frame (MRF) with reduced beam sections (RBS), and a frame with nonlinear viscous dampers and associated bracing (called the DBF). The emphasis is on assessing the seismic performance for the design basis earthquake (DBE) and maximum considered earthquake (MCE). Three MRF designs were studied, with the MRF designed for 100%, 75%, and 60%, respectively, of the required base shear design strength determined according to ASCE 7-10. The DBF with nonlinear viscous dampers was designed to control the lateral drift demands. Earthquake simulations using ensembles of DBE and MCE ground motions were conducted using the real-time hybrid simulation method. The results show the drift demand and damage that occurs in the MRF under seismic loading. Overall, the results show that a high level of seismic performance can be achieved under DBE and MCE ground motions, even for a building structure designed for as little as 60% of the base shear design strength required by ASCE 7-10 for a structure without dampers.     

翼缘削弱的型钢混凝土框架抗震性能研究

为了研究翼缘削弱的型钢混凝土框架的抗震性能,对一榀两跨三层型钢混凝土框架模型进行了低周反复荷载试验。框架模型按"强柱弱梁"原则设计,且对节点核心区附近梁端工字形型钢的上、下翼缘采取狗骨式削弱,并适当增加最大削弱部位纵向钢筋的配筋率。通过对框架模型顶层施加低周反复水平荷载,观察了框架模型的破坏过程,测得框架模型的荷载-位移滞回曲线和骨架曲线以及各阶段的荷载和位移值,并分析了框架模型的延性、耗能、强度降低、刚度退化以及破坏机制。试验结果表明:框架模型的承载能力、变形能力和耗能能力高,延性大(延性系数大于7),满足延性框架的抗震要求。进一步分析了翼缘削弱在型钢混凝土框架中的具体作用。分析结果表明:翼缘削弱不仅能将塑性铰从梁端根部转移到翼缘削弱部位,从而降低节点核心区所受的剪力以及梁柱连接焊缝的应力,而且有利于框架形成梁铰耗能机构,从而提高框架的整体耗能能力。翼缘削弱能有效提高型钢混凝土框架的抗震性能,可在型钢混凝土     

密柱支撑低层钢结构工业化住宅体系循环加载试验

密柱支撑低层钢结构工业化住宅体系为一种新型工业化住宅体系。通过对一个采用加强型高频焊接H型钢梁贯通式节点构造的足尺结构进行循环试验,揭示了该结构体系在水平地震作用下的抗侧力机制和破坏模式、抗震性能与恢复力特性,得出了其刚度、承载力、延性与耗能能力的变化规律,提出该类结构体系的设计建议。     

Experimental study on the seismic behavior of a shear wall with concrete‐filled steel tubular frames and a corrugated steel plate

Shear walls and core tubes in shear walls constitute the core anti‐earthquake vertical systems of high‐rise buildings. This paper proposes a new type of composite shear wall with concrete‐filled steel tubular frames and corrugated steel plates. The seismic behavior of the new shear wall is studied using a cyclic loading test and damage analysis. The failure mode, load‐carrying capacity, ductility, stiffness degradation, hysteresis behavior, and energy dissipating capacity exhibited in the test are studied. The test results show that when the proposed wall is broken, the tension side of concrete‐filled steel tubes is torn. The concrete at the bottom of the wall is detached and peels off along the through cracks. The energy dissipation capacity of concrete walls is more fully utilized. The proposed wall exhibits excellent deformability, energy dissipation capacity, and the stiffness degradation was slower than that of other walls. The use of corrugated steel plate significantly improved the seismic performance while simultaneously increasing the ductility and reducing the damage. In addition, this paper modified the energy dissipation factor in the Park & Ang model based on the situation of the specimen and experiment. It can be used to evaluate the damage degree of this new type of shear wall.     

半刚性框架-密肋网格复合钢板剪力墙结构抗震性能试验研究

对一榀单跨两层半刚性框架-密肋网格复合钢板剪力墙结构进行了低周反复荷载作用下的试验研究。系统分析了结构的受力机制、破坏模式和耗能机理,得到了承载力、刚度、延性及耗能能力等指标,评价了该种结构体系的抗震性能。结果表明：结构在弹性工作阶段主要依靠墙板的剪切机制承担水平荷载,非弹性阶段区格中钢板的对角拉力带为结构提供侧向承载能力;密肋网格的设置有效限制了内嵌钢板的面外变形值,提高了结构的弹性刚度,克服了滞回曲线的“捏缩”效应,减小了钢板的噪音及震颤,显著增强了结构的耗能能力;框架与钢板墙协同工作良好,结构塑性变形能力强,安全储备高,是一种优良的抗侧力体系;破坏模式为各区格中的钢板撕裂,拉力带效应明显,边框架柱脚及边框架梁端形成塑性铰。     

钢板剪力墙震后型钢斜劲修复结构的抗震性能研究

为研究钢板剪力墙结构在遭遇震害后的修复方法和修复后结构的抗震性能,对一榀缩尺比1∶3的单跨两层薄钢板剪力墙进行原始结构和修复结构低周往复荷载试验研究,在原结构加载结束后对受损结构采用型钢斜加劲肋的方法进行原位修复,研究钢板剪力墙震后型钢斜劲修复方法的有效性和修复后结构的抗震性能。同时,采用有限元软件ABAQUS模拟修复过程,进行修复结构与未修复结构二次遭遇低周往复荷载作用的性能对比研究,以及修复结构中型钢斜肋的肋板刚度比参数分析。研究结果表明:在设防地震阶段采用斜劲修复后,结构内嵌钢板面外变形得到有效恢复,斜劲修复与加固方法可行,同时有限元的"生死单元"法也可较好地实现修复过程的模拟;修复结构的承载力、弹性刚度和能量耗散量显著提高,分别相较未修复结构的提升12.06%、36.57%和57.72%;同时,斜劲修复有效减小了内嵌板的面外变形量,变形量较未修复结构降低37.69%,斜劲修复用肋的肋板刚度比阈值可选用50,即为传统纵横加劲钢板剪力墙竖向肋板刚度比的限值。     

An evaluation of energy response and cumulative plastic rotation demand in steel moment‐resisting frames through dynamic/static pushover analyses

In the energy‐based design approach, the seismic design is performed through the balancing of the energy input and the energy dissipation of the structure. The energy dissipation is represented by the hysteretic energy dissipation capacity defined as the total area enclosed in the force–deformation curves under cyclic loading. Thus, the energy‐based design approach considers the cumulative effect of the seismic loading of the structure. The cumulative damage in the structural members can be expressed in terms of cumulative plastic rotation (CPR). The CPR capacity plays an important role in determining the hysteretic energy dissipation capacity of a steel moment connection. This study investigated the energy response and the CPR capacity and demand through dynamic pushover analyses on steel moment‐resisting frames. The results were compared with the ones obtained from the pushover analysis. Copyright © 2008 John Wiley & Sons, Ltd.