This paper proposes a new toggle-style negative stiffness viscous damper (TNVD), and evaluates the performance of the TNVD with the displacement amplification factor (f_d) and the energy dissipation factor (f_E). Firstly, the composition and characteristics of the TNVD are introduced. Subsequently, the displacement amplification factor is introduced to evaluate the displacement amplification ability of the TNVD, and it is decomposed into a geometric amplification factor and an effective displacement coefficient. Then, based on the geometric amplification factor and effective displacement coefficient, the correlation between the TNVD’s displacement amplification ability and inter-story deformation is studied, and an improved TNVD is proposed. By the comparison of the finite element calculation results, it is found that the improved TNVD can utilize the assumption of small structural deformation. After that, the impacts of plentiful aspects, such as the length of the lower connecting rod, the horizontal inclination angle of the lower connecting rod, the inter-story deformation limit, the cross-sectional area of the connecting rod, the damping coefficient, and the negative stiffness on the f_d and f_E of the improved TNVD, are expounded. The research results show that when the length of the TNVD’s lower connecting rod remains unchanged, the f_d and f_E present a trend of increasing first and then decreasing with the increase in the horizontal inclination angle of the lower connecting rod. When the inter-story deformation is fixed, there exists an optimal lower connecting rod’s length that satisfies a specific relationship to achieve the optimal geometric amplification factor of the TNVD. By adjusting the damping parameters of the TNVD, we can obtain a better effective displacement coefficient greater than 0.95 in the proposed target region. Meanwhile, the f_d and f_E increase with the decrease in the negative stiffness. An optimization strategy for the improved TNVD has been proposed to ensure that the TNVD has the characteristics of operational safety, ideal displacement amplification capability, and energy dissipation capability. Furthermore, a multi-objective control design method with an additional improved TNVD structure is proposed. The vibration reduction effect of the structure with the improved TNVD and the effectiveness of the optimization strategy are verified through examples.

With the acceleration of modern urbanization, the height and density of buildings are increasing, and the need for seismic protection in structural design is becoming more and more urgent. The robust recovery, great reusability, and exceptional seismic performance of the viscous damper make it a popular choice for high-rise construction. To improve the seismic damping effect of the building structure, the study employs methodologies that the restoration force model simulates the viscous dampers’ resistance against the seismic forces, and the time course analysis method allows for analysis of the dynamic response of structures to seismic activities through time in realigning the position of the viscous damper. Furthermore, the study utilizes the multi-objective optimization method to optimize the distribution parameters of the damping structure, thereby enabling the design of a displacement-based vibration-damping structural configuration for the viscous damper. The results revealed that the maximum inter-story displacement angle produced by the studied seismic-damped structural design under five sets of natural seismic waves used for validation is 1/909, which is less than the displacement angle limit value of 1/1000, and meets the requirements of the Chinese code for seismic design of buildings (GB 50011 − 2010). In conclusion, the study of design for viscous dampers using displacements offers positive benefits with an inter-story displacement angle decrease of 41.93%, acceleration decrease of 16.27%, and layer displacement decrease of 6.72%. The conclusion would be useful for decision-making to give estimates of seismic losses during construction.

For the study of the mechanical properties of straight-tenon joints in traditional wooden structures, three specimens of T-shaped straight-tenon joints were made according to actual structures and subjected to reciprocating loading tests. The variation rules of different seismic performance indexes such as moment-rotation hysteresis curve, skeleton curve, stiffness, and energy dissipation capacity of the specimens were analyzed through tests. Based on the geometric deformation and static equilibrium conditions, the moment-rotation theoretical model of straight-tenon joints is derived and compared with the experimental results. The studies show that the hysteresis curve of joints under reciprocating loading consists of four stages: ascending, stress relaxation, descending, and sliding. The moment capacity of joints increases gradually with the rotational deformation, but the internal gap of the joints increases synchronously, resulting in a serious attenuation of the stiffness. Tenon and mortise plastic extrusion deformation and friction can dissipate energy, as the rotational deformation increases energy consumption, while the hysteresis loop “pinch” effect is more serious, and the equivalent viscous damping coefficient is gradually reduced. The prediction results of the joint moment-rotation theoretical model are closer to the experimental results, which can provide a theoretical basis for the overall seismic analysis of traditional wooden structures.

In this study, three types of viscoelastic laminated composite dampers (VLCDs) were fabricated and experimentally analyzed. The dampers were fabricated by adding mesh skeleton materials to acrylic rubber to increase its stiffness; this can provide greater restoring force to passive control structures under the same strain conditions. The mechanical properties of the VLCDs were studied by measuring the maximum shear stress, storage shear modulus, loss factor, and equivalent viscous damping ratio under the same ambient temperature and different loading schemes. The experimental results showed that: (1) the addition of aramid mesh skeleton material to the damper can improve its stiffness without changing the matrix of the damping material; (2) the strain amplitude significantly affects the mechanical properties of VLCDs; (3) the excitation frequency has a slight impact on these mechanical properties; and (4) the influence of large-strain low-cycle fatigue on these mechanical properties is significant during the first 15 cycles and less significant during the next 15 cycles. Furthermore, hysteresis curves were calculated and simulated using the Bouc-Wen-Baber-Noori model. The simulation and experimental results agreed well with each other.

Generally speaking, the traditional lever amplification damping system is installed between adjacent columns in a building, which occupies a significant amount of space in the building. In contrast to amplification devices in different forms, the damper displacement of the intermediate column damper system is smaller, and the vibration reduction efficiency is lower. In light of these drawbacks, this study proposes a new amplification device for energy dissipation and vibration reduction, which is based on an intermediate column–lever mechanism with a viscous damper (CLVD). Initially, a specific simplified mechanical model of CLVD is derived. Subsequently, an equivalent Kelvin mechanical model of CLVD is derived to intuitively reflect CLVD’s damping and stiffness effect. The damping ratio added by CLVDs to the structure is calculated according to that model; the additional damping ratio and additional stiffness are utilized to calculate the displacement ratio R_d and shear force ratio R_v of the structure with CLVDs to the structure without CLVDs. R_d and R_v are introduced to evaluate the vibration reduction effect of the structure with CLVDs, and the effects of various parameters (such as intermediate column position, beam’s bending line stiffness, lever amplification factor, damping coefficient, and earthquake intensity) on R_d and R_v are analyzed. The results indicate that when the ratio of the distance from the intermediate column to the edge column to the span of the beam is 0.5, CLVD owns the optimal vibration reduction effect. Increasing the beam’s bending line stiffness is beneficial for CLVD to control structural displacement and shear force; when the leverage amplification factor is too large, the CLVD provides the structure with stiffness as the main factor, followed by damping. Additionally, when the ratio of the displacement amplification factor to the geometric amplification factor satisfies f_d/γ = 1/2^1−0.5α, the CLVD has the optimal displacement control effect on the structure. After that, measures are provided to optimize the CLVD in different situations in order to effectively control the inter-story displacement and the story shear force of the structure. Consequently, a nine-story frame is taken as an example to elaborate the application of CLVDs in the design for energy dissipation and vibration reduction. The results reveal that the CLVD scheme adopting the proposed optimization method can effectively enhance the displacement amplification ability of CLVDs, resulting in an additional damping ratio of up to 12%. At the same time, the inter-story displacement was reduced by almost 40% under fortification earthquakes. Through the research in this study, designers can obtain a new choice in structural vibration reduction design.