PSI - Issue 44

A.Di Egidio et al. / Procedia Structural Integrity 44 (2023) 2136–2143 A. Di Egidio, S. Pagliaro, A. Contento / Structural Integrity Procedia 00 (2022) 000–000 Christchurch

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Fig. 6. Time-histories of u e , u 1 , and u 2 − u 1 : point A in Fig. 5

It worth observing that, in standard base isolation, an external structure similar to that used in this paper, is con nected in series at the base of the frame structure. In the structural scheme proposed in this paper the structure to be protect and the external system are connected in parallel. Nevertheless, both systems (the base isolation and the proposed one) works in a very similar way. Specifically: • the main oscillating mode acquire a modal mass participating factor higher than 90%; • the modal displacements mainly interest the external structure. A further analysis considered di ff erent ground motion records. The results of such an analysis were arranged in performance maps. Each map was realized varying the sti ff nesses of the external structure and the connection device. It is found that there are wide regions in the plane of the parameters where the coupling is beneficial for the frame structure. It can finally then asserted that: • the protection system, if well designed, makes the external structure able to work as a tuned mass damper; • in general, the protection system works as a seismic concealment for the structure to be protect since drives the main e ff ects of the earthquake towards the external structure. Bachmann, J., Vassiliou, M., Stojadinovi, B., 2017. Dynamics of rocking podium structures. Earthquake Engineering and Structural Dynamics 46, 2499–2517. Den Hartog, J.P., 1956. Mechanical vibrations, 4th edn. McGraw-Hill, New York . Di Egidio, A., de Leo, A., Simoneschi, G., 2016. E ff ectiveness of mass-damper dynamic absorber on rocking block under one-sine pulse ground motion. International Limits of Non-Linear Mechanics (DOI: 10.1016 / j.ijnonlinmec.2017.10.015). Di Egidio, A., Pagliaro, S., Fabrizio, C., 2021. Combined use of rocking wall and inerters to improve the seismic response of frame structures. Journal of Engineering Mechanics 147. Fabrizio, C., de Leo, A., Di Egidio, A., 2019. Tuned mass damper and base isolation: a unitary approach for the seismic protection of conventional frame structures. Journal of Engineering Mechanics 145, doi: 10.1061 / (ASCE)EM.1943–7889.0001581. Kelly, J., 1995. Base isolation: linear theory and design. Earthquake Spectra 6, 223–244. Makris, N., Kampas, G., 2016. Seismic protection of structures with supplemental rotational inertia. Journal of Engineering Mechanics 142. Pagliaro, S., Di Egidio, A., 2022. Archetype dynamically equivalent 3-d.o.f. model to evaluate seismic performances of intermediate discontinuity in frame structures. Pietrosanti, D., De Angelis, M., Basili, M., 2020. A generalized 2-dof model for optimal design of mdof structures controlled by tuned mass damper inerter (tmdi). International Journal of Mechanical Sciences 185, paper Id 105849. References