Steel beam-to-column connections equipped with SMA tendons and energy dissipating devices including shear tabs or web hourglass pins

Abstract

This paper presents a numerical study on two innovative classes of beam-to-column connections equipped with superelastic shape memory alloy (SMA) tendons as recentering elements and shear tabs or web hourglass steel pins (WHPs) as supplementary energy dissipating and shear resisting components. First, the finite element model of the shear tab connection with SMA tendons is produced and analyzed to validate the numerical analysis against the prior experimental results. Then, special cast high strength brackets are proposed to incorporate SMA tendons in the connections. Afterwards, a parametric study is performed considering the effects of shear tabs' presence, SMA tendons' initial prestress, shear tab bolts' initial prestress, coefficient of friction between shear tab and beam web, length/arrangement of SMA tendons and brackets, and shear resisting mechanism of the connection. Finally, additional class of SMA-based connections equipped with hourglass steel pins passing through the beam web is introduced, studied under cyclic loads, and examined when subjected to high levels of shear force demand. Results show that incorporating shear tabs and WHPs in the SMA-based connections, if properly designed and installed, not only improves their energy dissipation capability, but also can enhance their moment capacity, initial stiffness, and shear resistance, with no negative effect on the recentering ability.