SUMMARYWe present the results of the quasi-static cyclic tensile tests of Cu-Al-Mn shape memory alloy (SMA) bars of 4 and 8 mm diameters to examine their superelasticity and other mechanical properties closely related to seismic applications. The present Cu-Al-Mn SMA bars have achieved the recovery strains of over 8% and the fracture strains of over 17%. Low-cycle fatigue was observed in neither of the bars. The mechanical properties obtained from the test, along with the lower material cost and higher machinability than Ni-Ti SMAs, demonstrate the high potential of the present Cu-Al-Mn SMA bars to be used in seismic applications.

Experimental and numerical works are reported to assess the cyclic response of concrete beams reinforced with superelastic alloy (SEA) bars. The feasibility of newly developed Cu–Al–Mn SEA bars, characterized by large recovery strain, low material cost and high machinability, is examined as partial replacements for conventional steel bars, in order to reduce residual cracks in structures during and after intense earthquakes. Four-point reverse cyclic bending tests were done on one-third scale concrete beams comprising three different types of specimens—conventional steel reinforced concrete, SEA reinforced concrete and SEA reinforced concrete (RC) with pre-tensioning. The results showed that SEA reinforced concrete beams demonstrated strong recentering capability and significant enhancement in crack recovery capacity, in comparison to steel reinforced beams. Furthermore, corresponding finite element models were generated to simulate the experimental observations. Both the experimental observations and finite element computations illustrated the superiority of SEA bars to conventional steel bars in providing RC beam specimens with recentering and crack recovery capabilities.

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Summary Shaking table tests are performed on a one‐bay one‐story steel frame with superelastic Cu–Al–Mn shape memory alloy (SMA) tension braces. The frame is subjected to a series of scaled ground motions recorded during the 1995 Kobe earthquake, Japan. The test results demonstrate that the SMA braces are effective to prevent residual deformations and pinching. It is also shown that the time history responses observed from the shaking table tests agree well with the numerical predictions using a rate‐independent piecewise‐linear constitutive model calibrated to the quasi‐static component tests of the SMA braces. This suggests that the loading rate dependence of Cu–Al–Mn SMAs as well as the modeling error due to the piecewise linear approximation can be neglected in capturing the global response of the steel frame. Numerical simulations under a suite of near‐fault ground motion records are further performed using the calibrated analytical models to demonstrate the effectiveness of the SMA braces when the variability of near‐fault ground motions is taken into account. A stopper, or a deformation restraining device, is also proposed to prevent premature fracture of SMA bars in unexpectedly large ground motions while keeping the self‐centering capability in moderate to large ground motions. The effectiveness of the stopper is also demonstrated in the quasi‐static component and shaking table tests. Copyright © 2015 John Wiley & Sons, Ltd.