Low‐Cost Base Isolation with PVC‐Sand Systems: Performance Evaluation and Probabilistic Insights for Professional Design

This article investigates the seismic performance of an idealised two‐storey reinforced concrete school building supported on a novel, low‐cost, easy‐to‐implement seismic base‐isolation system entitled polyvinyl chloride “sand‐wich” (PVC‐s), conceived and experimentally verified at the University of Bristol. Requiring a modest additional cost and training for builders, the PVC‐s system uses locally available materials to achieve the intentional initiation of base sliding and dissipation of seismic energy through the encapsulation of sand grains between two sheets of unplasticized PVC. The system is expected to act as a “fuse” providing additional safety against extreme events, given that the superstructure is designed for strength and ductility according to seismic codes. The effectiveness of the system, previously verified experimentally by proof‐of‐concept shaking table tests, is systematically demonstrated herein through an extensive probabilistic framework of a 3D numerical simulation of a typical school building triaxially and incrementally excited by a suite of 30 ground motions. The adopted approach for simulating PVC‐s system response is cross‐verified against two supplementary modelling methods, including one different finite‐element implementation and one Bouc–Wen formulated semi‐analytical solution, as well as against previous full‐scale shaking table tests. The coupling between the strength and ductility capacities of the superstructure in relation to the sliding threshold of the PVC‐sand‐PVC isolation interface is scrutinised via comparative incremental dynamic analysis curves and predicted Damage States. Depending on system configuration and the properties of the earthquake ground motion, seismic demand experienced by the school building is estimated to reduce by 35%–65%. The analyses further establish the required width of the gap between the sliding foundation and the sacrificial perimeter parapet wall. Overall, the PVC‐s system is found to be a feasible, low‐cost alternative of seismic base‐isolation for low‐rise buildings appealing in both low‐income regions and beyond.