Large-Scale Testing for Enhancing the Resilience of Schools in Seismic Regions: Challenges and Cost-Efficient Solutions

This work presents the results of a large-scale experimental study aim- ing to investigate the seismic performance of a three-storey reinforced concrete school building supported on a novel, low-cost, easy-to-implement seismic base- isolation system entitled PVC ‘sand-wich’ (PVC-s). With a modest additional cost and training of builders, the PVC-s system uses locally resourced materials to achieve the intentional initiation of base sliding and the dissipation of seismic energy during earthquakes through the encapsulation of sand grains between two sheets of polyvinyl chloride (PVC) covering the area underneath the raft founda- tion. Given the prerequisite that the building is adequately designed as a standard earthquake resistant structure, the PVC-s system significantly enhances its seismic performance under moderate to extreme seismic events by acting as a ‘fuse’ that reduces the transfer of energy to the superstructure, while also achieving long term financial benefits by limiting the degree of seismic damage experienced during the life cycle of the structure. The effectiveness of the PVC-s system is shown experimentally and numerically through a probabilistic framework of incremental dynamic analyses (IDA) on a detailed three-dimensional finite-element model of the school building triaxially excited with a suite of 30 ground motions. Seismic demand reduction was estimated in the range of 30% to 70% for the design-level ground motion intensity and above. The analyses also contributed to optimising the length of the gap between the sliding system and the non-structural perimeter parapet wall that was not explored experimentally. The detailed experimental and numerical investigation demonstrate that the PVC-s system is a feasible, low-cost alternative for seismic isolation that can be appealing in low-income countries and beyond.