Numerical study and practical design of beam-to-column connections with shape memory alloys

This paper reports a comprehensive numerical study on end-plate beam-to-column connections equipped with NiTi shape memory alloys (SMAs). The numerical modelling strategy is first validated through comparisons with seven full scale tests conducted by the authors. The FE predictions correlate well with the test results, especially in terms of the deformation mode, strain reading, moment-rotation response, residual deformation, and equivalent viscous damping. Following the validation study, a parametric study is performed considering the effects of bolt layout, bolt length/diameter, beam-to-connection strength ratio, end-plate thickness, column web panel deformation, and shear resisting mechanism. In order to overcome a major issue identified from the parametric study, i.e. shear slippage, an improved HS-SMA hybrid solution is proposed. One of the novel concepts is the employment of HS bolts in collaboration with SMA Belleville washers, where the latter are used to absorb the bolt row deformation, to enable connection recentring, and to offer supplementary energy dissipation. A detailed FE model is established to confirm the feasibility of the HS-SMA hybrid connection, and an analytical model is also developed for normal design of such connections. A set of design rules for practical use are also proposed, and the required future studies are finally identified.