Damping in Civil Engineering Using SMA. The Fatigue Behavior and Stability of CuAlBe and NiTi Alloys

Two types of application in damping of structures by SMA in Civil Engineering are considered. The first one is related to the reduction of the damage produced by earthquakes. The second one is concerned with the increase of the lifetime of the stayed cables in bridges. The analyses of the experimental conditions required for each application are different: Several years or decades without any activity (excepted the summer-winter room temperature parasitic effects) followed by one or two minutes of oscillations under the earthquake affects, or near 100000 oscillations per day with pauses of several hours or days in the damping of stayed cables in bridges. This article analyzes the fatigue behavior of the CuAlBe alloy (appropriate for earthquakes) and of the NiTi alloy. Measurements of the damping of stayed cables indicate that the oscillation amplitude could be reduced up to one-third by using a NiTi wire as a damper device.