PSI - Issue 78

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 78 (2026) 2094–2101

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of XX ANIDIS Conference organizers Keywords: hybrid base-isolation system, HDRBs, viscous effects, push-and-release tests; Abstract Push and release tests on full-scale base-isolated buildings serve as in situ verification of the actual performance of base-isolation systems. However, for systems using High Damping Rubber Bearings (HDRBs), the test response is highly sensitive to the velocity during the pushing phase. When this velocity is low—often due to hydraulic system limitations—the free vibration response may significantly deviate from expectations based on the nominal properties of HDRBs, due to their viscous behaviour. To accurately interpret test results, a model that captures the strain-rate-dependent viscous effects is essential. In this paper a simple linear viscoelastic model, calibrated on laboratory tests on HDRBs, is proposed and shown to effectively reproduce the experimental response, including final residual displacements. It also confirms that the nominal properties of HDRBs and LFSs align with design specifications, even when deviations occur. 1. Introduction High Damping Rubber Bearings (HDRBs) differ from Natural Rubber Bearings (NRBs) due to the addition of fillers that enhance damping capacity but also introduce viscous behaviour, depending on the specific rubber compound used. This viscosity introduces velocity-sensitive effects, which are categorized into two types: short-term effects at high velocities (typical of seismic events) and long-term effects at low velocities (typical of quasi-static actions). These effects influence the mechanical response of HDRBs under different loading conditions. Specifically, XX ANIDIS Conference Simulation of push and release tests on HDRBs-based isolation systems accounting for viscous effects Laura Ragni a *, Fabio Micozzi b , Andrea Dall’Asta b a Università Politecnica delle Marche, Department of Civil and Building Engineering and Architecture, via Brecce Bianche, Ancona, Italy b Università di Camerino, School of Science and Tecnology, via Gentile III da Varano 7, Camerino (MC), Italy

* Corresponding author. Tel.: +39 071 2204553 fax: +39 071 2204576. E-mail address: laura.ragni@univpm.it

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of XX ANIDIS Conference organizers 10.1016/j.prostr.2025.12.266