Improving the Efficiency of a Novel Controlled-Sliding-Based Isolation System for Brick Masonry Structures

Low-rise brick masonry buildings are considered the most vulnerable type of structures when they are subjected to seismic excitation. Base isolation is considered a widely adopted strategy to enhance the seismic performance of low-rise brick masonry buildings. Previously developed sliding-based isolation systems did not specifically determine the most adequate combination of isolation layer thickness and the recentering mechanism that will result in the best isolation performance. Accordingly, this study investigates the identification of the best-performing configuration of the previously developed base isolation system through extensive numerical studies and experimental verification. The critical parameters considered in this research are the suitable thickness of the isolation layer and the spacing of the recentering rebars. A finite element analysis was conducted on a 1∶3 reduced scale unconfined brick masonry wall model. The first set of models was having a constant isolation layer thickness of 63.5 mm and four different values of recentering rebars spacings (i.e., 152.4, 203.2, 254, and 304.8 mm). The second set of numerical models consists of varying isolation layer thicknesses such as 50, 63.5, and 76 mm, and a constant recentering rebars spacing of 152.4 mm. It was concluded that the suitable value of isolation layer thickness is 63.5 mm with recentering rebars located at a distance of 152.4 mm because it gives the maximum amount of seismic energy dissipation. Later on, the isolator was experimentally verified using a reduced scale unconfined brick masonry wall subjected to displacement controlled cyclic loading tests. Finally, a case study was conducted to verify the performance of the proposed isolator in a full-scale school building.