Steel and SMA angles
As we know, steel angles are widely used in semi-rigid connections (e.g. top-and-seat angles and web angles). However, for past studies of steel angle mechanical models, most of them focused on uni-directional loading. The cyclic behavior of steel angles and its potential energy dissipation capability received relatively little attention. In our study, we tried to investigate the mechanical behavior of steel angles under the loading-unloading process and furthermore, to investigate the functionality of Ni-Ti SMA angles and to use them as self-centering seismic-resistant devices in the connection.
For steel angles, the result shows fat hysteresis loops, which indicate good energy dissipation capability of the angle. For SMA angles, moderate energy dissipation capability and good self-centering performance can be observed. There are some discrepancies between the experimental testing results and numerical modeling results. Those might be from material properties definition, e.g. steel will have some hardening effect during the loading-unloading process; and the proper of SMA is highly dependent on the heat treatment temperature. Those are hard to capture but generally, the agreement is good and the discrepancies are thought to be acceptable.
Wang B, Zhu S, Chen K, Huang J. Development of superelastic SMA angles as seismic-resistant self-centering devices, Engineering Structures, 2020, 218: 110836 https://doi.org/10.1016/j.engstruct.2020.110836