In order to improve the damping capacity of building isolation system, this paper studies the damping isolation control system of the building structure based on negative stiffness. In this paper, the dynamic equation of the damping isolation control system is derived and its parameters are optimized by H₂ norm theory and Monte Carlo pattern search method. Taking the 5-story building structure as an example, this paper analyzes and evaluates the damping performance of the damping isolation control system of the building structure under the actual earthquake. The results show that negative stiffness can improve the damping capacity of traditional isolation system. Additionally, the negative stiffness ratio under the condition of stability, the smaller the negative stiffness ratio, the stronger the vibration reduction ability of the negative stiffness. The damping isolation control system of building structure based on negative stiffness shows good damping effect under the actual earthquake.

The study analyzed the influence of random defects on plateau stresses of honeycomb materials with varied relative densities and established a computational model of honeycomb materials considering random defects. The results show that the plateau stress decreases evidently as the random defects increase, which is closely related to the relative density of honeycomb materials. It also set up a functional relationship between relative plateau stresses and random defects as well as that between relative plateau stresses and relative densities. Taken topological structure, random defects and strain rate effect into consideration, and it proposed a dynamic constitutive model of honeycomb materials under low‐middle impact loading. And the proposed constitutive model possesses a better applicability to match the stress‐strain relationship of honeycomb materials in existing impact experiments. The proposed constitutive model could make a theoretical foundation in material design and practical application of honeycombs containing random defects.

The overlapping decentralized control strategy is a solution to the decentralized control of large-scale systems based on the inclusion principle. Its design process can be summarized as three stages of expansion-decoupling-contraction. In this paper, the subsystem division scheme of the overlapping decentralized control strategy is studied for building structure systems under earthquake. Using the energy-to-peak algorithm, we mainly analyse the influences of the location of the overlapping layer, the number of overlapping layers and the number of subsystems on the control effect of the structural system, and compare them with the traditional energy-to-peak centralized control method. The numerical results indicate that the dynamic response of the structure can be effectively suppressed by raising the location of the overlapping layer, increasing the number of overlapping layers, and increasing the number of subsystems. Compared with the centralized control strategy, the control effect is equivalent, or even better, verifying the feasibility of this research scheme.

Blasting load is investigated using LS-DYNA software for the tunnel structure with different densities of expanded polystyrene (EPS) granule layers. Analysis of different points of pressure shows that the presence of EPS granule layers has beneficial effects on the attenuation of the stress wave, and the pressure decay exponent increases with the increase in particle density. In addition, the presence of EPS granule layers can reduce the tensile stress caused by the impact of the free surface of the tunnel. A mathematical model of the pressure attenuation index relative to EPS grain density and relative distance is established.

To enhance the mechanical performances of traditional honeycombs, a novel combined honeycomb (HKH) was proposed based on the regular hexagonal honeycomb (RHH) and Kagome honeycomb (KH). A systematic investigation of the in-plane dynamic crushing behaviors of the honeycombs was conducted via the finite element method, and the crashworthiness characteristics of the three honeycombs were examined. Using one-dimensional shock wave theory and least squares fitting, a fitting formula of the plateau stress was obtained, and the deformation mechanism of the HKH was determined based on the elastic buckling of the cell wall. The results showed that the HKH exhibited a higher plateau stress than the RHH for any velocity impact, while the negative Poissons ratio effect was more significant than that of the KH for low-velocity impacts (the peak Poissons ratios of the HKH and KH were 0.312 and 0.286, respectively). Furthermore, the effects of the impact velocity and relative density on the energy absorption and auxetic performances were explored. In this study, a novel design was proposed by combining various cell elements to obtain better crashworthiness, providing a new concept to promote the development of lightweight materials.