In the past decades, several experimental and analytical investigations showed that the dynamic behavior of buildings can be significantly affected by the interaction with a soft foundation soil. In such cases, the actual response of structures founded on shallow foundations can be successfully simulated if the structural model is equipped with springs and dashpots calibrated through frequency-dependent impedance functions. This paper discusses the results of a research project aimed at back-calculating the impedance functions of a shallow square foundation from records of the dynamic behavior of the EuroProteas soil-foundation-structure (SFS) facility, deployed at Euroseistest (Greece). To this aim, forced-vibration tests were executed under different frequencies and increasing loading amplitudes. The experimental impedances were compared with several analytical solutions available in the literature, accounting for different hypotheses on the subsoil model. This comparison improved when the shear wave velocity VS used to define the analytical functions was reduced accounting for the strain level mobilized by the increasing amplitude of the applied force. A numerical model was realized in the SAP2000 software. The compliance of foundation soil has been introduced using elastic springs, the stiffness of which was calibrated considering either the analytical or the experimental impedances. The fundamental frequency obtained from a modal analysis of the SAP2000 model equipped with the springs calibrated on the experimental impedances turned out to reproduce the fundamental frequency of EuroProteas effectively measured on-site. Such results showed the effectiveness of using experimental impedance functions in the numerical simulations, especially when equivalent soil parameters are hard to define.
On the effectiveness of experimentally-derived foundation impedance functions / Amendola, C.; de Silva, F.; Pitilakis, D.; Silvestri, F.. - 2021-:(2021). (Intervento presentato al convegno 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2021 tenutosi a grc nel 2021).
On the effectiveness of experimentally-derived foundation impedance functions
Amendola C.;de Silva F.;Silvestri F.
2021
Abstract
In the past decades, several experimental and analytical investigations showed that the dynamic behavior of buildings can be significantly affected by the interaction with a soft foundation soil. In such cases, the actual response of structures founded on shallow foundations can be successfully simulated if the structural model is equipped with springs and dashpots calibrated through frequency-dependent impedance functions. This paper discusses the results of a research project aimed at back-calculating the impedance functions of a shallow square foundation from records of the dynamic behavior of the EuroProteas soil-foundation-structure (SFS) facility, deployed at Euroseistest (Greece). To this aim, forced-vibration tests were executed under different frequencies and increasing loading amplitudes. The experimental impedances were compared with several analytical solutions available in the literature, accounting for different hypotheses on the subsoil model. This comparison improved when the shear wave velocity VS used to define the analytical functions was reduced accounting for the strain level mobilized by the increasing amplitude of the applied force. A numerical model was realized in the SAP2000 software. The compliance of foundation soil has been introduced using elastic springs, the stiffness of which was calibrated considering either the analytical or the experimental impedances. The fundamental frequency obtained from a modal analysis of the SAP2000 model equipped with the springs calibrated on the experimental impedances turned out to reproduce the fundamental frequency of EuroProteas effectively measured on-site. Such results showed the effectiveness of using experimental impedance functions in the numerical simulations, especially when equivalent soil parameters are hard to define.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
