SEISMIC RETROFIT OF OLD CONCRETE STRUCTURES USING SHAPE MEMORY ALLOYS

Lateral loadings, like earthquakes, induced on structures often lead to great damage or structural failure. Using materials with high energy dissipating property will be of great value since it can minimize the structural damage when it is subjected to earthquake laodings. Shape memory alloy (SMA) is one of those smart materials with high energy dissipating property. In this paper SMA have been used as bracing systems for seismic retrofit of old concrete structures. Retrofitting results of an old structure with SMA braces have been compared with the results of the same structure but using steel braces; which have been tested under different excitations. The considered structure has a frame behavior and since concrete structures with a frame behavior has a flexural nature, producing recentering effect will be very desirable which has been produced by the superelastic behavior of SMAs. Finite element method is used in this study to analyze the concrete structures subjected to dynamic time history loadings and cyclic loadings. The results indicate that the system with SMA is capable of recovering most of the permanent residual strain in the structure; and hence achieves reasonable improvement in seismic response.

Keywords:

Retrofit , Shape Memory Alloys , Recetering effect , Passive Control , Finite Element Method