Base Isolation for Earthquake Protection of Structures Considering Ethiopian Standard

Abstract

An increase in construction activities and recent advances in structural engineering necessitated the major revision of the Ethiopian Building Code Standard (EBCS), published in 1995. The updated building code has introduced improved earthquake-resistant design considerations, including provisions for base-isolated (BI) structures. This study investigates the efficacy of the base isolation technique in earthquake protection of buildings considering Ethiopian standard. Moreover, the validity of the specific provisions of the Ethiopian seismic standard, i.e., Ethiopian Standard European Norm, (ES EN 1998-1:2015) on the choice of base isolator properties for analysis and design is investigated. Non-linear dynamic response history analyses of multi-story BI buildings are performed under synthetic earthquakes, matching with the response spectrum of the Ethiopian standard. Furthermore, the vibration response of fixed-base building models is reported for comparison. Four structural response quantities, i.e., the floor acceleration, base shear, inter-story drift, and isolator displacement, are studied. The findings demonstrate that the application of the base isolation technique reduces the dynamic response of multi-story buildings substantially. In addition, it is shown that some of the Ethiopian seismic standard provisions on isolator parameter consideration are not in logical agreement with the earthquake behavior of BI buildings observed in the current study.