Quantitative analysis of seismic energy balance and dissipation in soil-structure interaction systems

While traditional seismic analysis focuses only on peak displacement and acceleration responses of structures, energy-based analysis evaluates structural damage throughout the entire loading process. During an earthquake, the soil layer surrounding the structure dissipates a significant portion of the seismic energy. This paper analyzes energy dissipation in soil-structure interaction (SSI) systems. The temporal and spatial distributions of energy dissipation in SSI systems are examined. We summarize and analyze plastic energy-dissipation formulations for materials applicable to SSI models, explicitly including plastic free energy. A benchmark consisting of soil layers, a foundation, a column and an upper concentrated mass was developed in the Real-ESSI finite element numerical simulation software to analyze its energy response under seismic excitation. The effects of the upper concentrated mass, structural height, foundation elastic modulus and soil damping ratio on the plastic energy dissipation in SSI systems were investigated. The results indicate that increasing either the upper concentrated mass or the structural height leads to more significant plastic energy dissipation in the SSI system. To evaluate plastic energy dissipation in a realistic SSI system subjected to seismic loading, a 12-story hotel building in Ventura, California was modeled in Real-ESSI. Numerical simulation results show that plastic energy dissipation in this real SSI system during the 1994 Northridge earthquake is primarily concentrated near the pile foundation.