Predictive equations and continuum FE models for self-centering response of SMA-based steel beam-column connections with steel angles

Abstract

The main objective of this study is to develop predictive equations for characterizing the cyclic response of steel beam-to-column connections with superelastic Shape Memory Alloy (SMA) bolts and steel angles. High-fidelity continuum finite-element (FE) models are developed to simulate the cyclic behavior and limit states of steel beam-column connections with combined SMA bolts and steel angles. The simulation results are then validated against a set of seven full-scale connection specimens from a previous experimental study. The validated models are then used to perform sensitivity and response surface studies. The sensitivity analysis results with sixteen design factors indicate that the beam web slenderness ratio, SMA bolt diameter, and angle thickness are the most significant design factors influencing the cyclic response of SMA connections. The results also indicate that permanent deformation in the connection subassembly is confined to steel angles, confirming the robust damage-avoidance design of the beam-column connections with SMA bolts and steel angles. Beams of lower depth are recommended to prevent early bolt fracture and minimize residual deformations in SMA connections. The developed surrogate models can be used to accurately predict the cyclic and self-centering response of the SMA connections. A design example is also presented to illustrate the use of the surrogate models.