As a classic issue, structural seismic bearing capacity could not be accurately predicted since it was based on a structural ultimate state with inherent uncertainty. This result led to rare research efforts to discover structures’ general and definite working laws from their experimental data. This study is to reveal the seismic working law of a bottom frame structure from its shaking table strain data by applying structural stressing state theory: (1) The tested strains are transformed into generalized strain energy density (GSED) values. (2) The method is proposed to express the stressing state mode and the corresponding characteristic parameter. (3) According to the natural law of quantitative and qualitative change, the Mann–Kendall criterion detects the mutation feature in the evolution of characteristic parameters versus seismic intensity. Moreover, it is verified that the stressing state mode also presents the corresponding mutation feature, which reveals the starting point in the seismic failure process of the bottom frame structure. (4) The Mann–Kendall criterion distinguishes the elastic–plastic branch (EPB) feature in the bottom frame structure’s normal working process, which could be taken as the design reference. This study presents a new theoretical basis to determine the bottom frame structure’s seismic working law and update the design code. Meanwhile, this study opens up the application of seismic strain data in structural analysis.

Porcelain electrical equipment is prone to brittle failure due to resonance under seismic effects. To improve its seismic resistance, some researchers have conducted research on shock absorption technology for porcelain electrical equipment. However, extant research fails to provide a detailed and systematic study of the effect of the nonlinear characteristics of these shock absorbers on the performance of equipment under seismic effects. This paper provides a theoretical analysis, verified by shaking table testing, of the performance of a 1000 kV pillar-type porcelain lightning arrester. The Bouc–Wen model is fitted to the force-displacement curve of hysteretic nonlinear metal shock absorbers, and a dynamic model of, and equations for, pillar-type porcelain electrical components are derived, taking into account their nonlinear characteristics. This reveals the influence of the nonlinear characteristics of shock absorbers on the nonlinear seismic response characteristics of these components. Our results indicate that the seismic responses of pillar-type porcelain components can be effectively suppressed by hysteretic nonlinear shock absorbers and that the greater the intensity of the seismic waves, the more obvious the efficiency of shock absorption. However, as the installation radius and yield force of the installed shock absorbers increase, their shock absorption efficiency gradually decreases.

Frequent aftershocks often follow a strong mainshock. They can significantly increase cumulative damage to a structure. A model of a five-story reinforced concrete frame structure was designed and a nonlinear mathematical model of the structure was developed to investigate the damage states resulting from different mainshock-aftershock sequences. Mainshock-aftershock sequences consisting of one of three recorded mainshocks combined with one of five recorded aftershocks were created for input to the mathematical model. Inelastic energy dissipation and the Park-Ang damage index were used as measures of cumulative damage to the structure. The results demonstrate that consideration of only the single mainshock ground motion in seismic building design can result in the design and construction of unsafe buildings. Total cumulative damage to a structure is caused by the combination of damage states resulting from the mainshock and the aftershock(s).