In this study, a new type of viscoelastic (VE) damper with strong nonlinear characteristics, showing both softening and hardening, is investigated. Firstly, its performance tests are executed, and its mechanical properties summarized. Then, a shaking table test on a three-story viscoelastically damped structure is designed to investigate the dissipation characteristics and control effect of this type of VE damper. Six VE dampers were installed in pairs at each story and connected vertically to the upper and lower beams. The structure with additional VE dampers and that without additional VE dampers was subjected to three ground motions whose peak ground accelerations varied from 0.1 to 0.6 g. The experimental results indicate that the control effect on the displacements was remarkable, while the effect on accelerations and shear forces was limited, due to the damper's additional stiffness. With the increment of the damper deformation, the additional stiffness decreased, while the additional effective damping ratio increased at first and then declined. Finally, a simplified analytical method is proposed and applied to simulate the shaking table test using OpenSees. The simulating results validate the analytical method of this type of VE damper.

SummaryViscoelastic (VE) dampers, composed of VE layers sandwiched between relative rigid steel plates, have been widely used as dissipation devices to improve performance of structures under dynamic loads. Corresponding analytical and experimental investigations have been carried out by many scholars. However, most of VE dampers studied before are typically traditional dampers applied in regular structures. This paper introduces a new type of VE damper with strong nonlinearity used in the complex and irregular structure of Nanjing Dabaoen Temple. The new VE dampers show obvious nonlinear behavior, improved capacity of dissipation, and larger additional stiffness compared to the traditional ones. Nanjing Dabaoen Temple is a high‐rise steel structure by use of 112 new VE dampers. To investigate dissipation characteristics and control effect of the VE dampers in the complex structure, we established a suitable finite element model using SAP2000 software in which the VE dampers were simulated by Maxwell and Wen models connected in parallel, and then nonlinear time history analysis is executed using seven ground motions of moderate earthquakes and three of major earthquakes. Analytical results indicate that control effect of the VE dampers on structural displacement is preferable to that on structural acceleration and shear force due to dampers' additional stiffness. In addition, owing to incremental deformation of VE dampers under major earthquakes, damping effect of the VE dampers on all structural responses under major earthquakes is more obvious than that under moderate earthquakes. Analytical methods and conclusions in this paper will provide significant reference for analysis, design, and application of complex high‐rise structures added with VE dampers.

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There are similarity relations in hysteretic loops and parameters of viscoelastic (VE) dampers with same material but various sizes. Similarity coefficients of damper force and deformation of hysteretic loops were derived, and then similarity coefficients of characteristic parameters of VE dampers with various sizes were obtained consequently. Based on the similarity criteria, if the hysteretic loops of one of a series of VE dampers with same material but various sizes are obtained through test, then hysteretic loops of other dampers can be derived easily. Two kinds of VE dampers with different sizes have been tested under various strains to verify the proposed similarity criteria. The similarity criteria can be used in design of related tests and structural seismic design.

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This paper presents the use of buckling-restrained braces (BRBs) in the design of the main building of a thermal power plant as an alternative for the construction of such kind of large industrial facilities. The project is located in Suqian, Jiangsu Province, a region of high seismic demand (Intensity 8) in China. The main lateral force resisting system used for the structure of this project is composed of a combination of conventional concentrically braced frames (CBFs) and buckling-restrained braced frames (BRBFs). The paper explores the seismic design and performance assessment of this industrial steel building according to the provisions of the Chinese code. Response spectrum analysis and time-history analysis were conducted under two levels of seismic hazard: minor earthquake (63.2%/50 years) and major earthquake (2%/50 years). Results indicate that BRBs effectively helped to control lateral deformation and dissipated energy in stable manner, making the structure composed of CBFs and BRBFs to show the seismic performance as intended by the code.

This paper proposes a new viscoelastic (VE) material damping device with hybrid non-linear properties. Compared with traditional linear material dampers, the new non-linear VE material damping device is characterized by its better energy dissipation and deformation capability. The series performance tests of the VE device are conducted, based on which the sources and variation law of material non-linearities are analyzed. Five aspects of material non-linearities are summarized, including the shape change of hysteresis loop caused by phase difference, the initial stiffness caused by large loading rate, the softening effect caused by high temperature and fatigue, and the softening and stiffening effect under large strain deformation. A mechanic model for this device is proposed which considers multiple non-linear effects of the material. For the verifications of the proposed mechanic model, a shaking table test on a steel frame equipped with the new VE devices is designed and performed. Based on the proposed mathematic mechanic model, the numerical mechanic model is implemented in the OpenSees software. The accuracy of the mechanic model is firstly verified by comparing the performance tests data with the simulation results. Then the numerical model is also used to calculate the time history response of the shake table tested steel frame under earthquake loading. It is concluded that the mechanic model can well-depict several non-linear material behaviors of the new VE device, and the corresponding numerical model created in the open source calculation platform is reliable to be used to calculate non-linear time history response of a structure equipped with the new VE material damping devices.