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Steel moment-resisting frames are prone to extensive damage in seismically active zones. Large permanent deformations in structural members following strong earthquakes can be mitigated using smart materials such as shape memory alloys. In this article, three-dimensional finite element analyses are conducted to study the seismic performance of beamcolumn connections incorporating shape memory alloy plates. Eight beam-column connection subassemblies with shape memory alloy plates in the plastic hinge of beam were analyzed under cyclic loading. Based on the numerical results, the recentering properties of superelastic shape memory alloy plates were found to be effective in reducing the residual drifts of a flange plate beam-column connection, while displaying an excellent ductility. In addition, shape memory alloy plates could prevent the occurrence of local buckling and damage in structural members. The new self-centering connections could also exhibit a good energy dissipation capability.

SUMMARY This paper determines the seismic performance of four‐storey concentrically braced frames equipped with either steel buckling‐restrained braces or buckling‐restrained superelastic shape memory alloy (SMA) braces through incremental dynamic analysis. The incremental dynamic analysis technique is used to examine the behaviour of four‐storey braced frames with four different bracing configurations (including diagonal, split‐X, chevron‐V and inverted‐V) under 20 different ground motion records. The study reveals a satisfactory performance at the design intensity level for both types of braced frames. The results show that the SMA braces lead to a uniform distribution of inelastic response over the height of the buildings, as well as mitigating seismic response in terms of maximum inter‐storey drift and residual roof displacement. By comparing the responses of SMA and buckling‐restrained braced frames under higher intensities of earthquake loading, it is found that the SMA braces can be more beneficial especially under severe ground motion excitations. Copyright © 2014 John Wiley & Sons, Ltd.

Driven by a need to reduce repair costs and downtime in structures following a major earthquake, self-centering systems have been introduced. Post-tensioned high strength steel strands have shown promising results in providing self-centering capability in steel frames, where the beams are compressed to columns. This study aims at investigating the feasibility of using reduced length of steel and shape memory alloy strands in steel beam–column connections. Through finite element modeling, the study first evaluates the effect of using short-length regular post-tensioned strands in steel connections. The results show higher strength, stiffness, and energy dissipation capacity for connections with shorter length regular post-tensioned strands. The moment capacity and energy absorption capacity of a post-tensioned beam–column connection with one-third strand length were 105% and 114% higher than those of with full-length strands, respectively. However, residual drifts increased from 4 to 39 mm. To avoid loss in the re-centering capability of such connections due to yielding/failing of post-tensioned steel strands, the application of shape memory alloy and hybrid strands are proposed. The results show that shorter length shape memory alloy strands are effective in regaining self-centering and dissipating higher amount of energy compared to the full-length steel strands.

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