EFFECTIVE STIFFNESS AND DAMPING RATIO OF SEISMIC BASE ISOLATION SYSTEM OPTIMIZATION IN 2-DIMENSIONAL STRUCTURES LINEARLY ANALYZED FOR VARIOUS EARTHQUAKE ACCELERATIONS USING TABU SEARCH ALGORITHM

• Main Author: Sherin Kurnia, Vinsensia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/79747
• Institution: Institut Teknologi Bandung

A seismic base isolation system protects structure from damages during an earthquake. The two linear parameters which represent it are lateral effective stiffness and damping ratio. A lower structural acceleration response is achieved by decreasing the effective stiffness. However, this could increase the displacement on isolator. Thus, a higher damping ratio is required. Optimization is needed in order to have a minimum structural acceleration response and isolator displacement. In this study, an optimization of seismic base isolation system is conducted to minimize peak roof acceleration (PRA) to peak ground acceleration (PGA) ratio using tabu search (TS) algorithm. The observed structure is a 2 dimensional 4-storey hospital. The PGA values are obtained from risk-targeted maximum considered earthquake (MCER) response spectrum of Samarinda, Pekanbaru, Ambon, Jakarta, Palu, and Manokwari. The analysis performed in this study is linear time history. Isolator displacement and moment capacity of beam are constraining the optimization. The algorithm uses Python programming language and implements SAP2000 Open Application Programming Interface (OAPI). This study proves that TS performs well in generating optimum solution of seismic base isolation system problem. In one of the case, optimization was done for 4 times. All of them produced a consistent optimum solution. Optimum solutions which were obtained from this study can be used for determining base isolation parameters for a similar building located in a specific PGA. Another result is that a large isolation displacement is inefficient in decreasing PRA to PGA ratio.