ABSTRACT
Shape memory alloys are special metallic materials that combine two or more alloys to accomplish certain features. Several types of these alloys are available and have been used in many products but their application in civil/structural engineering has been limited. The particular feature that was of interest in the current study was the superelastic memory effect that allows the SMA yield and dissipate energy but return to its original length upon stress removal under a range of temperature representing those encountered in bridges. The most common type of SMA with this feature is a combination of Nickel and Titanium of approximately equal proportions know as Nitinol (NiTi). The ECC is a grout composed of cement, sand, water, and a patented poly vinyl fiber. It might include fly ash as a substitute for a part of the cement. What makes ECC unique is its ability to undergo large tensile strains of up to 5%. Micro-cracks develop but are spanned by fibers that through a special coating allow for partial slip and relatively large deformations. By using SMA/ECC in column plastic hinge zones it is possible to substantially reduce concrete spalling and damage and to minimize residual lateral displacements (Saiidi & Wang 2006, Saiidi et al. 2007, Saiidi et al. 2009).
