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The influence on the seismic behavior of RC shear walls by axial loads is evaluated and the observed damage in the earthquake damage investigation of RC shear walls is reproduced in this paper. Six RC shear walls with aspect ratio of 2 were analyzed by the method of nonlinear finite element under different axial load ratios, and the suggested modeling techniques and the accuracy of the numerical method were verified. The seismic performance of shear walls including load–displacement responses, ductility performance, stiffness degradation and energy dissipation capacity were discussed. The analysis results indicate that axial load has a significant effect on the seismic performance of RC shear walls. On the basis of this, the qualitative and quantitative relationships between the development of material damage and the deterioration of component performance were analyzed. It realizes the cross-scale conversion of damage information about structural components of RC shear wall from the local material scale to the component scale. Then the cross-scale refinement model of damage evolution of RC shear walls in the whole process was established, simplified and verified. The results show that, the refinement model can explain the development and distribution of damage evolution of RC shear walls in the whole process quickly and easily. The research results can provide a reference for the refinement of seismic design, damage assessment and reinforcement of RC shear walls. [ABSTRACT FROM AUTHOR]

• The controller-extensible HSP based on Matlab-OpenSees frameworks is developed. • The developed Matlab-OpenSees interface has good communication flexibilities. • The hybrid test results verify the accuracy and robustness of the developed HSP. • A series of hybrid tests on viscoelastically damped frame structures are conducted. Most of hybrid simulation platforms (HSPs) that use OpenSees for structural hybrid testing research are developed based on OpenFresco framework software. Although OpenFresco is mature and reliable, it can only communicate with specific hydraulic servo actuator control systems, which limits the diversity and flexibility of HSP development. Matlab has powerful independent development functions, and has a wide range of communication interface advantages with many finite element software and actuator control systems. Therefore, Matlab can be used as the communication medium between OpenSees and actuator control system in this study. Firstly, the controller-extensible HSP based on Matlab-OpenSees frameworks is developed. Then, the core establishment details of HSP, including core architecture, hardware system, and DELTA-Matlab-OpenSees system, are analyzed and described in detail. Next, the dynamic loading tests on the spring components are carried out when the HSP is subjected to continuously changing working conditions in the wide frequency domain and displacement amplitude domain. The comparative analysis results on the target displacement curve and the measured displacement curve verify the accuracy and robustness of the inner control loop of HSP. Next, the hybrid tests on a three-story reinforced concrete frame structure with linear springs are implemented under different seismic wave excitations. The comparative research on the hybrid test results and time-history analysis results verifies the accuracy and robustness of the developed HSP (outer control loop) in this study. Lastly, on this basis, a series of hybrid tests on viscoelastically damped frame structures are conducted under different seismic wave excitations. The test results truly reveal the control rule on the seismic response of reinforced concrete frame structures affected by viscoelastic dampers. [ABSTRACT FROM AUTHOR]

• A user-programmable hybrid simulation platform is established. • The methods for solving equation for viscoelastically damped structures are proposed. • The reliability of the hybrid simulation platform to test nonlinear systems is verified. • A series of hybrid simulation experiments for viscoelastically damped structures are implemented. To truly reflect the influence on structural seismic response control using viscoelastic dampers with strong nonlinear properties and reduce the cost and difficulty of experimental research, a new user-programmable hybrid simulation platform is developed. The core implementation details of this platform, including the core architecture, software system, and testing setup, are described. To better realize accuracy and stability of the hybrid simulation experiment, methods for solving the equivalent force equilibrium equation for hybrid simulation experiments on viscoelastically damped structures are proposed. Then, the mechanical properties of the experimental substructure (viscoelastic damper) are tested under different temperatures, amplitudes and frequencies, and the mathematical model parameters of the experimental substructure are identified. A seismic response comparison of viscoelastically damped structures obtained by the hybrid simulation experiment and the time history analysis verifies the robustness and reliability of the hybrid simulation platform to test nonlinear systems. Lastly, a series of hybrid simulation experiments for viscoelastically damped structures under different temperatures, seismic intensities and seismic waves are implemented using this hybrid simulation platform for the first time. The experimental results reveal the influence on structural seismic response control by viscoelastic damper under different temperatures, seismic intensities and seismic waves. [ABSTRACT FROM AUTHOR]

• An advanced frame structure system retrofitted by adding haunch viscoelastic damping braces is presented. • The seismic behavior and rebar strain at key locations of CFs and VFs are discussed. • A comparative study on the damage evolution about two types of frames at the material scale is carried out. • The addition of HVEDB guarantees the seismic design requirements of "strong nodes and weak components. To upgrade the existing RC frame structure system with insufficient seismic design and improve the seismic design of the RC frame structures, a novel and advanced frame structure system retrofitted by adding haunch viscoelastic damping braces (HVEDB) is presented in this study based on the good energy dissipation performance, the low-cost and non-invasive addition of viscoelastic dampers. For a comprehensive and systematic research of this new structure system, the seismic behavior of ten RC frames and another ten RC frames added by HVEDB with the axial load ratio (ALR) of 0.1–1.0 are carried out under horizontal sinusoidal steady-state excitation loading, including the hysteretic behavior, load-bearing capacity, stiffness degradation, energy dissipation capacity, additional damping ratio and rebar strain at key locations. On this basis, four reasonable damage indicators at the material scale are proposed, and a comparative study on the damage evolution about two types of frames at the material scale in the whole process is carried out. The study results show that the addition of HVEDB can greatly improve the seismic performance such as load-bearing capacity, lateral stiffness, deformation capability and energy dissipation, and it changes the failure mode of the RC frames. The HVEDB can provide the effective protection for the beam-column joints by transferring the damage region from the beam-column joint to the frame beam successfully, which guarantee the seismic design requirements of "strong nodes and weak components" avoiding the brittle failure mode of frame structure under high ALR. [ABSTRACT FROM AUTHOR]

• Full-scale experimental investigation on precast concrete sandwich wall panel structure is conducted. • Precast concrete sandwich panels are applied as load-bearing components, realizing the low-energy building with structural performance and thermal insulation property. • A novel dry connection is proposed, including the enclosed angle steel outer frame and multipoint bolt connections, and verified its efficiency under strong ground motion. • Seismic performance of precast concrete sandwich wall panel structure is evaluated by shaking table tests and seismic fragility analysis. A novel, light-weight, sustainable, repairable and cost-effective precast concrete sandwich wall panel structure system is proposed in this paper, including the dry bolt connections and the precast concrete sandwich panels. To evaluate the seismic performance of precast structure system, a sequence of shaking table tests is carried on the full-scale precast concrete sandwich wall panel structure, and the dynamic characteristics, damage pattern, dynamic responses and seismic fragility are investigated and analyzed by the test results under service level earthquake, design based earthquake, and maximum considered earthquake. The seismic fragility curves and failure probability curves are analyzed by the shaking table test results, which quantitatively describes the seismic performance expressed by probability. The results show that the precast concrete sandwich wall panel structure performs high lateral stiffness, large safety margins and high strength reserves. The precast concrete sandwich wall panel structure system presents a good seismic performance. The damage of the structure is slight under maximum considered earthquakes, and the structure has begun to enter the plastic stage. The light-weight characteristic reduces the dynamic responses, and the mild sliding between precast components consumes a fraction of seismic energy. [ABSTRACT FROM AUTHOR]