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Earthquakes and Structures Volume 4, Number 6, June 2013 , pages 607-627 DOI: https://doi.org/10.12989/eas.2013.4.6.607 |
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Loading rate effect on superelastic SMA-based seismic response modification devices |
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Songye Zhu and Yunfeng Zhang
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| Abstract | ||
| The application of shape memory alloys (SMAs) to the seismic response reduction of civil engineering structures has attracted growing interest due to their self-centering feature and excellent fatigue performance. The loading rate dependence of SMAs raises a concern in the seismic analysis of SMA-based devices. However, the implementation of micromechanics-based strain-rate-dependent constitutive models in structural analysis software is rather complicated and computationally demanding. This paper investigates the feasibility of replacing complex rate-dependent models with rate-independent constitutive models for superelastic SMA elements in seismic time-history analysis. Three uniaxial constitutive models for superelastic SMAs, including one rate-dependent thermomechanical model and two rate-independent phenomenological models, are considered in this comparative study. The pros and cons of the three nonlinear constitutive models are also discussed. A parametric study of single-degree-of-freedom systems with different initial periods and strength reduction factors is conducted to examine the effect of the three constitutive models on seismic simulations. Additionally, nonlinear time-history analyses of a three-story prototype steel frame building with special SMA-based damping braces are performed. Two suites of seismic records that correspond to frequent and design basis earthquakes are used as base excitations in the seismic analyses of steel-braced frames. The results of this study show that the rate-independent constitutive models, with their parameters properly tuned to dynamic test data, are able to predict the seismic responses of structures with SMA-based seismic response modification devices. | ||
| Key Words | ||
| shape memory alloy; superelasticity; loading rate effect; damper; constitutive model | ||
| Address | ||
| Songye Zhu : The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, Yunfeng Zhang : Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA | ||