Mitigation Response of Steel Structure using Shape Memory Alloy Dampers

Abstract

Different innovative controlling systems have been introduced into the literature in the last two decades varying from passive to active and smart control systems. Shape memory alloys (SMAs) are one of these systems with unique properties and behaviors which have made them and appealing material for use in dampers. SMAs exist in two crystallographic phases: the parent austenite phase and the product martensite phase. SMA materials are favorable for use in seismic applications, because of their recentering capability in austenite phase, high damping capacity in martensite phase and very high fatigue and corrosion resistance in both phases. I this paper, it is shown by analytical measures and by using proper constitutive relations for SMA materials that an ideal behavior can be obtained for a proposed Special SMA damper when using proper proportions of SMAs in austenite and martensite phases. The damper is devised so that produces maximum obtainable damping capacity while maintaining its recentering capability. By performing nonlinear dynamic time history analyses for selected structures enforced with buckling restrained steel braces and special SMA dampers, the permanent residual deformations remained on the structures after earthquakes are compared. The results show the effectiveness of implementation of SMA dampers while the main advantage is shown to be the drastic mitigation of the permanent deformations remained on the structure when using the proposed SMA dampers.