UBC Theses and Dissertations
Cyclic performance of self-centering post-tensioned steel beam-column connections using shape memory alloy energy dissipators Chowdhury, Md Arman
Driven by a need to reduce repair costs and downtime in structures following a major earthquake, self-centering (SC) systems have been introduced. Post-tensioned (PT) high strength steel strands have shown promising results in providing the SC capability in steel frames, where the beams are compressed to columns. In this study, the lateral cyclic performance of the SC connections is assessed through finite element analysis. At the beginning, the lateral load-deformation behavior of previously tested experimental specimens is validated with three-dimensional finite element models. The validated models are then modified accordingly to investigate the applicability of other techniques, i.e. stiffened angle connection, or other types of materials, i.e. shape memory alloy (SMA). Through design of experiment methodology, parametric studies in component level, i.e. stiffened angle, are conducted to provide some insight into the effect of different stiffener sizes on the strength and energy dissipation capacity of the connection. Afterward, four different techniques of incorporating SMA in the SC connections are proposed based on extensive parametric studies. Segmented PT connection is possible with shorter length SMA strand which can even sustain higher drift demand compared to the SC connections with steel strand. Hybrid strand, i.e. combination of steel strand and SMA strand, can further reduce the amount of SMA material in the connection. The use of SMA angles as energy dissipaters will remove the need for the replacement of the energy dissipating elements due to damage. Lastly, the applicability of SMA bolts in end-plate based interior and exterior connections are investigated through a parametric study.
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