Partially encased composite columns consist of thin-walled built-up H-shaped steel sections with links welded near the flange tips and concrete cast between the flanges. The use of PEC columns under concentric axial load only was incorporated into the Canadian steel design standard, CAN/CSA S16-01, in 2001 and the use of PEC columns as beam-columns is permitted in the current edition, CSA S16-09 (CSA 2009). A half-size two-storey one-bay steel plate shear wall specimen, with PEC columns as the boundary elements, was tested under vertical and cyclic lateral loads to study its behaviour, and good ductility and performance was observed. A finite element model of the specimen was also developed and loaded in a push-over analysis with a dynamic explicit solution strategy to help study the behaviour of PEC columns and the whole system.;The failure mode of the test specimen was the initiation of tears at the outside column flange tips at the bottom of the columns during the formation of plastic hinges. The specimen behaved in a ductile manner with no rapid drop of the specimen strength after the ultimate capacity was reached. Compared with steel plate shear walls with a steel frame, more nonlinear behaviours were observed in the specimen due to the existence of the concrete, which led to severely pinched hysteresis curves without a clear yield portion. Although the energy dissipation capacity did not keep increasing until the end of the test, it did increase beyond the value observed when the ultimate capacity was reached. Based on the test data, strain hardening occurred in the first floor infill panel and the corresponding finite element material curve was modified accordingly. In general, the model gave good predictions of the overall specimen behaviour and internal frame forces.
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