Investigating the Influence of Dynamic Interaction Between Primary and Secondary Structures on Elastic Floor Response Spectra During Near- and Far-Field Earthquakes: A Comparative Analysis with EC8 Formulation

Abstract

Analyzing secondary structures (SSs) during earthquakes is vital due to their vulnerability and potential impact on building functionality and occupant safety. Understanding the seismic performance of SSs requires analyzing the Floor Response Spectra (FRS). This research investigates how the dynamic interaction between the primary structure (PS) and SSs affects the FRS under near-field (NF) and far-field (FF) earthquake conditions. Both the elastic PS and SS are modeled as single-degree-of-freedom (SDOF) systems. The governing equations of motion of the PS and SS are derived and numerically solved using the RK4 method.  The study examines the influence of the PS vibration period (Tp), tuning ratio (Tr), mass ratio , and SS damping ratio on FRS. Twenty horizontal ground motion excitations were selected for the study. Time-history analysis results indicate that the dynamic interaction is negligible at a lower mass ratio . For values of 0.01, 0.1, and 0.5, the peak acceleration response of the SS under near-field (NF) excitation decreased by 15.7%, 68.3%, and 79.1%, respectively, and by 15.2%, 68.9%, and 78.8% under far-field (FF) excitation, compared to the uncoupled case. The spectral acceleration response of the SS is significantly influenced by dynamic interaction within dynamic interaction has no effect on FRS across all considered  values. Parametric analysis showed that NF earthquakes induce larger FRS peaks compared to FF events. In conclusion, a comparison between simulated FRS and those predicted by Eurocode 8 shows discrepancies, with the code-based formulation often either underestimating or overestimating the FRS magnitude.

Keywords

• dynamic interaction
• far-field earthquakes
• floor response spectra
• near-field earthquakes
• non-structural component