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Vibration control technologies have been widely implemented for the seismic retrofitting of buildings in high seismic regions. Among various vibration control devices, the tuned viscous mass damper (TVMD) has proven effective in mitigating both lateral inter-story drifts and floor accelerations. This paper presents the seismic design and performance assessment of a retrofitted structure located in a highly seismic area. The existing masonry building is being retrofitted into a steel frame-jacketed masonry wall interacting structural system installed with TVMDs. A simplified iterative design process is proposed for the tuning design of TVMDs used in the retrofitted structure, which is based on the fixed-point method. The seismic responses of the buildings are calculated using non-linear dynamic analysis in OpenSees. Applying the FEMA P-58 approach, the seismic performance of the buildings as measured by the repair cost and repair time is evaluated. The findings reveal that the majority of the structural damage is focused within the masonry walls, coupling beams, and non-structural components. Use of TVMDs results in reduced maximum inter-story drifts that when subjected to very rare earthquake (VRE) shaking are up to approximately 40% lower in both transverse and longitudinal directions compared with the uncontrolled structure. Owing to the effective control of seismic damage to both structural and non-structural components, the TVMD-equipped structure achieves a 42% reduction in median repair cost and a 46% reduction in median repair time at VRE compared with the uncontrolled building. The seismic performance assessment results also illustrate the advantages of TVMD control compared with conventional viscous dampers. • A real-world case study for a retrofitted building using TVMD is presented. • A simplified iterative process is proposed for optimal design of TVMD. • TVMDs effectively control inter-story drift and floor acceleration responses. • Control advantages of TVMDs are illustrated by comparison with viscous dampers. • Use of TVMDs leads to significant reduction of post-quake repair cost and time. [ABSTRACT FROM AUTHOR]

Summary An innovative hybrid coupled wall system consists of reinforced concrete (RC) wall piers connected with replaceable steel coupling beams (RSCBs) throughout their height. The RSCBs are designed with a central "fuse" shear link connected to steel beam segments at both ends, which are capacity designed to remain elastic. During a damaging earthquake, the fuse shear links yield and dissipate seismic energy, and once damaged, they can be easily replaced due to specialized link‐to‐beam connection details. Therefore, this system is expected to provide enhanced seismic performance over a conventional RC coupled wall system, particularly in terms of repair costs and time after damaging earthquakes. This paper presents an overview of seismic design considerations of this new system, which is intended as a guide for design practitioners to adopt the system. Design procedure of this system is first summarized, followed by description of the coupling ratio selection, member sizing, connection detailing, and modeling recommendations of the system. Furthermore, an analytical case study for a high‐rise building is presented to highlight the benefit of using this system for enhancement to overall building performance. In the end, this paper presents a few real‐world applications of RSCBs in super‐tall buildings in China. [ABSTRACT FROM AUTHOR]

In recent years, a novel type of hybrid coupled wall (HCW), which consists of reinforced concrete (RC) wall piers and replaceable steel coupling beams (RSCBs), has been proposed for enhancing the seismic resilience of high-rise buildings. This paper presents the assessment of the seismic performance of an 11-story building located in a highly seismic area and designed per modern Chinese codes. The building adopts the frame-shear wall interacting system. For comparison, two cases are considered: one using the novel hybrid coupled walls and another using conventional RC coupled walls (RCW). The dynamic response of the buildings under high intensities of ground motion shaking is obtained from nonlinear dynamic analysis in OpenSees. The seismic performance, expressed in terms of repair cost and time, is assessed based on the FEMA P-58 method. The results indicate that most of the damage is concentrated in the coupling beams and nonstructural components. The use of novel HCWs instead of conventional RCWs results in maximum interstory drifts up to 24.5% lower in the HCW building than the RCW building when subjected to a maximum considered earthquake (MCE) intensity. Novel HCWs result in a reduction of 50.8% and 60.5% in the median building repair cost and time, respectively, under MCE, due to less damage to coupling beams and RC frames and easy replacement of RSCBs after a damaging earthquake. It is also noted that HCWs have limited influence on the peak floor accelerations, and thus the repair cost and time for acceleration-sensitive non-structural components are similar for both the HCW building and the RCW building. [ABSTRACT FROM AUTHOR]

This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design method. Comparison of the design provisions of the GB 50011-2010 code and those of the American code ACI 318-14 indicates a possible deficiency in the T-shaped wall design provisions in GB 50011-2010. A case study of a typical T-shaped wall designed in accordance with GB 50011-2010 also indicates the insufficient extent of the boundary element at the non-flange end and overly conservative design of the flange end boundary element. Improved designs for special boundary elements of T-shaped walls are developed using a displacement-based method. The proposed design formulas produce a longer boundary element at the non-flange end and a shorter boundary element at the flange end, relative to those of the GB 50011-2010 provisions. Extensive numerical analysis indicates that T-shaped walls designed using the proposed formulas develop inelastic drift of 0.01 for both cases of the flange in compression and in tension. [ABSTRACT FROM AUTHOR]

SUMMARY The steel tube-reinforced concrete (ST-RC) composite column is a novel type of composite column, which consists of a steel tube embedded in RC. In this paper, the seismic behavior of ST-RC columns is examined through a series of experiments in which 10 one-third scale column specimens were subjected to axial forces and lateral cyclic loading. The test variables include the axial force ratio applied to the columns and the amount of transverse reinforcement. All specimens failed in a flexural mode, showing stable hysteresis loops. Thanks to the steel tube and the high-strength concrete it is filled with, the ST-RC column specimens had approximately 30% lower axial force ratios and 22% higher maximum bending moments relative to the comparable RC columns when subjected to identical axial compressive loads. The amount of transverse reinforcement made only a small difference to the lateral load-carrying capacity but significantly affected the deformation and energy dissipation capacity of the ST-RC columns. The specimens that satisfied the requirements for transverse reinforcement adopted for medium ductile RC columns as specified by the Chinese Code for Seismic Design of Buildings (GB 50011-2010) and EuroCode 8 achieved an ultimate drift ratio of around 0.03 and a displacement ductility ratio of approximately 5. The design formulas used to evaluate the strength capacity of the ST-RC columns were developed on the basis of the superposition method. The predictions from the formulas showed good agreement with the test results, with errors no greater than 10%. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents seismic retrofit for the single-story brick-wood structure representative of existing rural buildings in Beijing. The retrofitting effectiveness was examined through large-scale shaking table tests on the unretrofitted and retrofitted specimens. The test results indicate that, for the unretrofitted specimen, the front brick columns deform and damage severely when subjected to the longitudinal motions, because large of lateral stiffnesses difference exists between the front and back longitudinal walls. The brick gables experience significant out-of-plane deformation, resulting in diagonal cracks. The unretrofitted specimen is cracked under minor earthquakes, significantly damaged under design basis earthquakes, and approaches to collapse under rare earthquakes. The method of seismic retrofit was proposed based on the test results of the unretrofitted specimen, including the addition of a steel doorframe, steel window frames and steel plate collar beams, and the strengthening of the brick gables and columns by cement mortar reinforced with steel mesh. Shaking table test results show that the retrofit method significantly improves the earthquake-resistant capacity of the brick-wood building structure, and the retrofitted specimen can achieve the design objective of 'operational under minor earthquakes, repairable damage under design basis earthquakes, and collapse prevention under rare earthquakes'. [ABSTRACT FROM AUTHOR]

Abstract: In strong earthquake events, multi-story concentrically braced steel frames (CBFs) are prone to form a story-collapse mechanism after buckling and yielding of the braces in a story. With the addition of continuous gravity columns and the increased lateral stiffness and strength they provide, however, it becomes possible to reduce the concentration of story drift and prevent the story collapse. Nonlinear dynamic analysis is implemented for a three-story CBF, and it is demonstrated that a drift concentration is inevitable, particularly in the first story, when the CBF is subjected to a set of large ground motions with a probability of exceedance of 2% in 50 years. A simplified theoretical formulation is presented to characterize the effect of gravity columns. Two cases are considered: gravity columns perfectly fixed, and gravity columns pinned at the base. It is noted that significant mitigation of drift concentration can be achieved, particularly when gravity columns are fixed at the base. Nonlinear time-history analysis is further performed to validate the theoretical observations and quantify the stiffness/strength demands of gravity columns to avoid drift concentration. The analysis results support the trends and observations obtained from the theoretical formulation. Finally, numerical simulations are implemented with the seismic force reduction factor , slenderness ratio of braces , and number of stories, as major analysis variables. The results demonstrate that a few (e.g. four) fixed-base gravity columns can lead to collapse prevention for reasonably designed low-rise CFBs under the set of large ground motions. [Copyright &y& Elsevier]

• Full-scale tests were conducted on steel coupling beam-to-SRC wall joints. • The steel coupling beam-to-SRC wall joints failed in panel shear mode. • The capacity designed joint had slight damage upon to failure of steel beam. • Design model for calculating the nominal joint strength is presented. • Mechanism and accuracy of design model are validated by test data and FE analysis. A hybrid coupled wall system, where steel coupling beams couple steel reinforced concrete (SRC) walls in series, has been recognized as an alternative to reinforced concrete (RC) coupled wall systems for enhanced seismic performance of high-rise buildings. A key issue of this system is seismic design of steel coupling beam-to-SRC wall joints. This paper presents a series of full-scale tests to investigate the cyclic behavior and strength capacity of the steel coupling beam-to-SRC wall joints, where a steel beam was rigidly connected to an encased steel column in wall boundary using a fully welded connection detail. The steel beam-to-SRC wall joints failed in panel shear mode, characterized by yielding of the steel web panel and joint transverse reinforcement, and crisscrossed-diagonal cracking and crushing of joint panel concrete. A design model for calculating the nominal strength of the steel beam-to-SRC wall joint is presented. The accuracy of the design model was verified against the collected test data and additional finite element (FE) analysis. The experimental tests and FE analysis also identified that severe vertical cracks might develop along the inner side of wall boundary element, due to horizontally tensile forces induced by the steel beam flange. Increased amount of horizontally distributed rebar is recommended to be assigned in around the join region, in order to control such unwanted damage. In addition, the test results of one specimen demonstrated that properly designed beam-to-wall joint remained slightly damaged when the steel coupling beam fully developed its plastic rotation. [ABSTRACT FROM AUTHOR]