Self-Centering Beam-to-Column Connections with Combined Superelastic SMA Bolts and Steel Angles

Abstract

This paper reveals the great potential of using combined superelastic shape memory alloy (SMA) bolts and steel angles for self-centering connections with variable performance targets. Eight full-scale specimens were tested, and the main parameters included SMA bolt prestrain, bolt length, angle thickness, and layout of bolts and angles. The specimens showed desired yielding sequences and deformation modes. The inelastic deformation was accommodated by the SMA bolts and angles with no damage to the column and beam. The specimens also exhibited very good self-centering abilities at 2% drift, beyond which the self-centering abilities were dependent on the considered parameters. A ductility capacity of at least 4% was provided by all the specimens. The maximum equivalent viscous damping ranged between 11 and 15%, indicating moderate energy dissipation. Following the test program, a design framework for such connections was proposed, and a calculation example was provided to further illustrate the proposed design procedures. The design framework was also validated through comparing the design predictions against the test results in terms of residual connection rotation.