Haibo Wang

In earthquake engineering and hydraulic engineering, the dynamic mechanical behavior of cohesive soils is crucial to ensure structural stability. However, most existing dynamic constitutive models fail to adequately account for the influence of strain history, which is essential for accurately predicting soil behavior under seismic loading. This study conducted a series of cyclic single-shear tests on both in situ and disturbed Changsha cohesive soils. Hysteresis curves were obtained under varying shear strain amplitudes to investigate the degradation patterns of the dynamic shear modulus and the evolution of the damping ratio. Furthermore, multi-cycle loading tests under constant strain amplitude were carried out to clarify the correlation between damping ratio, dynamic shear modulus, and the number of loading cycles. A simplified practical dynamic model, applicable to general cohesive soils, is proposed. This model incorporates the effect of strain history and provides a valuable reference for analyzing the dynamic response of soils subjected to earthquake actions.

Composite post insulators are crucial facilities in substations and are prone to significant damage during seismic disasters. However, existing research lacks seismic motion models suitable for power facilities and rarely involves stochastic models. Furthermore, considering the non-stationary characteristics of seismic motion, predicting the response of nonlinear systems under non-stationary excitation becomes exceedingly challenging. In view of this, the stochastic response of composite post insulators under the non-stationary stochastic seismic excitation appropriate for power facilities has been studied. First, a stochastic ground motion model, conforming to the Code for Seismic Design of Electrical Insulators in China, is established, incorporating amplitude and frequency non-stationarity. Next, the nonlinear dynamic system, accounting for multi-section composite post insulators and the nonlinearity of flange connections, is established under stochastic ground motion conditions. Based on this stochastic nonlinear dynamic model, the dynamic behavior of the system was analyzed using the stochastic dynamics method (the wavelet-Galerkin method), and the influence of nonlinear stiffness on the system response was discussed. The stochastic seismic response analysis method proposed in this paper can serve as a valuable reference for the seismic design of pillar-type electrical equipment.

Transformer is key equipment in the power transmission and transformation system. When the seismic calculation is carried out, the foundation soil is generally considered to be absolutely rigid, and the bottom of the structure is considered as the fixed end, the soil-structure interaction is ignored. This paper is aimed to study the soil-structure interaction’s impact on the seismic performance of the transformer and other power facilities by carrying out cyclic shear test on cohesive soil, simulating the dynamic response of clay soil under the seismic load, and get the nonlinear dynamic characteristics parameters of the soil in the loading process of seismic cycles. On the basis of the study, the fitting equation of the dynamic shear modulus and damping ratio of the soil is put forward through analyzing the cohesive soil dynamic hysteresis constitutive model.