Georgia Tech model analyzes shape-memory alloys for use in earthquake-resistant structures

 

At the Georgia Institute of Technology, researchers are analyzing shape-memory alloys for their potential use in constructing seismic-resistant structures. “Shape-memory alloys exhibit unique characteristics that you would want for earthquake-resistant building and bridge design and retrofit applications: they have the ability to dissipate significant energy without significant degradation or permanent deformation,” said Reginald DesRoches, a professor in the School of Civil and Environmental Engineering at Georgia Tech. Georgia Tech researchers have developed a model that combines thermodynamics and mechanical equations to assess what happens when shape-memory alloys are subjected to loading from strong motion. The researchers are using the model to analyze how shape-memory alloys in a variety of components -- cables, bars, plates and helical springs -- respond to different loading conditions. From that information, they can determine the optimal characteristics of the material for earthquake applications. The most common shape-memory alloys are made of metal mixtures containing copper-zinc-aluminum-nickel, copper-aluminum-nickel or nickel-titanium. Potential applications of shape-memory alloys in bridge and building structures include their use in bearings, columns and beams, or connecting elements between beams and columns. But before this class of materials can be used, the effect of extreme and repetitive loads on these materials must be thoroughly examined.