Seismic base isolator for adobe dwellings in Chile

Abstract

This thesis explores the effects of employing an affordable seismic base isolator (SBI) in adobe dwellings in Chile. The SBI is formed by two components located between the footing and the foundation wall of the adobe housing unit, acting together during the seismic event. These components are (1) the frictional interface layer, which diffuses horizontal forces by employing 6 to 8 mm pebbles and (2) the re-centering piece, which limits lateral displacements and relocates the adobe structure in the center of gravity by employing scrap tire lock-donuts. The SBI was seismically analyzed in a 650 sf one story adobe dwelling with 18" wall thickness. The seismic analysis uses the package SAP 2000 and the static analysis method required by Chilean seismic design code. Results show that the SBI case C1 reduces seismic forces in about 17.5%. Also, the differences between the maximum seismic stresses and the admissible wall stresses is 5 [lb/in2] shorter than by using polymer mesh, diminishing damaged areas generated in the wall in about 11.4%, which is 2% less of affected area if the adobe dwellings protected with polymer mesh. This system also augments the total cost in 2%, which is almost half of employing polymer mesh.