Study On Performance-Based Practical Design Method For Seismic Isolated Retrofitting Structures

In this paper, the state-of-the-art of seismic retrofitting of structure with isolators and performance-based design method at home and abroad, performance based design idea are introduced. Based on the nonlinear character of the isolation system and static nonlinear analysis, a practical performance-based design method for seismic isolated retrofit structure is developed. The primary studies are as follows:(1) With the state-of-the-art of structure performance levels and performance objects both home and abroad, three performance levels of seismic retrofitting of structures with isolators are descriibed as, good function, life safety and collapses. Prevention. Three design objects of seismic retrofiting structure with isolators are defined for buildings with different importance factors, which are "no damage for small earthquakes, repairable for moderate earthquakes and no collapsing", "no damage for moderate earthquakes and repairable for large earthquakes" and "no damage for large earthquakes".(2) Pushover analysis is suggested for the the seismic design of isolated retrofit structure, the lateral load patterns and loading control manner are studied in detail. The seismic performance of the seismic isolated retrofit structure system is evaluated by capacity spectrum method based on the pushover analysis.(3) Based on the performance based seismic design theory, a practical performance based design method for seismic isolated retrofit structure is presented. With this method, isolation bearings can be designed fastly. And the pushover analysis is recommended to check the seismic performance of the preliminary design. Combining all these steps, a emtire practical design procedure is put forward finally.