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.

SUMMARY This paper investigates the feasibility of tension braces using Cu–Al–Mn superelastic alloy bars as energy dissipating and self‐centering elements for steel frames by performing 1/3 scale shaking table tests. The difficulty with conventional steel tension braces lies in pinching or significant deterioration of stiffness and strength under cyclic loading. When a steel frame with conventional tension braces is subjected to intense earthquakes, pinching may lead to a large residual drift and/or instability. To overcome the difficulty, this paper examines the effectiveness of Cu–Al–Mn superelastic alloy bars, facilitated by their large recovery strain, low material cost, and high machinability, as a partial replacement of steel bars in tension braces. In the shaking table tests, a 1/3 scaled 1‐bay, 1‐story steel frame with the present tension braces is subjected to quasi‐static cyclic loading and dynamic harmonic ground motions of 6 Hz. Both the static and dynamic test results demonstrate the effectiveness of the present braces in avoiding pinching under the ductility ratio up to 3. The dynamic test results also demonstrate the capability of the present tension braces in reducing the peak response acceleration within the base shear capacity. To study the rate dependence of the frame response, further, time‐history analyses are performed by using a SDOF model based on a uniaxial rate‐independent model, calibrated with the quasi‐static tests. A comparison of the analytical results with the dynamic test results demonstrates that the rate dependence of the frame response is negligible up to the loading frequency of 6 Hz. Copyright © 2014 John Wiley & Sons, Ltd.

We report the results of tensile cyclic loading tests conducted to examine the dependence of constitutive relations for superelastic Cu–Al–Mn alloy rods on loading rates. Recently, Cu–Al–Mn alloy rods with diameters up to 8 mm have been developed by the authors, and it has been demonstrated that these rods have excellent superelastic strains of more than 8%, which is comparable to Ni–Ti alloys and far superior to other Cu-based alloys. No information is available, however, on the rate dependence of constitutive relations for Cu–Al–Mn alloys. In this study, we prepare two Cu–Al–Mn alloy rod specimens, whose lengths and diameters are 150 mm and 8 mm, respectively. Their stress–strain relations are examined under the loading frequencies of 0.001, 0.5, and 1 Hz with constant strain amplitude of 4.5%. It was found from the tests that the maximum stress increase in Cu–Al–Mn alloys due to higher loading rate was less than 5%. Thermo-mechanical analysis predicts that stress increase in Cu–Al–Mn alloys is about 1/4 of that in Ni–Ti alloys, which agrees reasonably well with the experimental observations. Such low stress increase is highly desirable in the design of seismic devices such as dampers and isolators.