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Showing 2 results for Shape Memory Alloy

M. Saiidi, C. Cruz, D. Hillis,
Volume 8, Issue 1 (3-2010)

Three unconventional details for plastic hinges of bridge columns subjected to seismic loads were developed,

designed, and implemented in a large-scale, four-span reinforced concrete bridge. Shape memory alloys (SMA),

special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning

were used in three different piers. The bridge model was subjected to two-horizontal components of simulated

earthquake records of the 1994 Northridge earthquake in California. The multiple shake table system at the University

of Nevada, Reno was used for testing. Over 300 channels of data were collected. Test results showed the effectiveness

of post-tensioning and the innovative materials in reducing damage and permanent displacements. The damage was

minimal in plastic hinges with SMA/ECC and those with built in elastomeric pads. Conventional reinforced concrete

plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse

reinforcement. Analytical studies showed close correlation between the results from the OpenSEES model and the

measured data for moderate and strong earthquakes.

A.r. Khaloo, I. Eshghi, P. Piran Aghl,
Volume 8, Issue 3 (9-2010)

In this paper the response of cantilevered reinforced concrete (RC) beams with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is SuperelasticShape Memory Alloys (SE SMAs) which contains nickel and titanium elements. The SE SMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this study, different quantities of steel and smart rebars have been used for reinforcement andthe behavior of these models under lateral loading, including their load-displacement curves, residual displacements, and stiffness, were discussed. During lateral loading, rebars yield or concrete crushes in compression zone in some parts of the beams and also residual deflections are created in the structure. It is found that by using SMA rebars in RC beams, these materials tend to return to the previous state (zero strain), so they reduce the permanent deformations and also in turn create forces known as recovery forces in the structure which lead into closing of concrete cracks in tensile zone. This ability makes special structures to maintain their serviceability even after a strong earthquake

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