Effectiveness of Base Isolation Using Single Friction Pendulum in Plan Irregular Structures

Base isolation is found to be a very efficient earthquake-resistant construction method. When base isolation is introduced, the transfer of large amount of inertia forces is prevented by the moving action of an isolator during an earthquake. The application of base isolator in regular buildings is done from long before, but the usage and effectiveness of base isolation in irregular buildings are a topic which needs more research. In this study, single friction pendulum isolator is used to isolate the buildings and the effectiveness of isolators is discussed in regular as well as plan irregular buildings. Modal analysis and time history analysis using Chi-Chi earthquake accelerogram data is done. Time period obtained from modal analysis and the results of time history analysis, such as base shear, storey acceleration and storey drift of regular, as well as plan irregular buildings are compared. The time period is found to increase significantly and base shear, acceleration and storey drift are decreased significantly with the application of single friction pendulum isolator. Also, the effectiveness of isolator got reduced with the introduction of irregularity in the structure.