STRUCTURAL SYSTEM ENABLING PROMPT RECOVERY AFTER EARTHQUAKES

摘要

After experiencing catastrophic earthquakes in major cities worldwide in 1990's and 2000's, the general public recognized that the economical loss due to the out-of-service period for repairing the damaged building was more significant than the cost to rehabilitate the damaged building itself. The base isolation system is one of the solutions to keep building functions after earthquakes, but the initial and maintenance costs are too high to apply to all kinds of buildings. The authors proposed a new economical structural system which enables prompt recovery after earthquakes using precast prestressed concrete frames with energy dissipating elements. Precast prestressed concrete structures show high self-centering characteristics with negligible damage and enable prompt recovery, if the excessive drifts due to nonlinear elastic behavior are reduced by using some energy dissipating elements. The structural system with precast concrete frames and energy dissipators satisfy the social demand with much less cost compared to that of the base isolation system. This paper introduces two types of the structural system and describes the design concepts. The focal point is the optimization of self-centering and energy dissipating properties. An FEM model was developed to simulate experimental results with high accuracy. From this analysis, a simplified calculation method was proposed to estimate hysteretic characteristics of the structures with each types of the system. Finally, design procedures for optimization of the restoring performance and the amount of energy dissipators were introduced.