CHUNG-CHE CHOULin T.H.Lai Y.C.Xiong H.C.Uang C.M.El-Tawil S.McCormick J.P.Mosqueda G.2026-03-122026-03-122021https://www.scopus.com/record/display.uri?eid=2-s2.0-105027837025&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/736226Recent studies showed that the seismic performance of steel columns is affected by the boundary conditions at both ends of the member. To reflect realistic boundary conditions, five half-scale, two-story steel subassemblage frames with a single column and steel beams at two floors were tested to evaluate the cyclic behavior of steel columns. The prototype design was based on a seven-story apartment building in Taiwan. The building is a dual system with a special moment-resisting frame (SMRF) and a buckling-restrained braced frame (BRBF). Three subassemblages (Specimens HC-37, HC-37-R and HC-49) used H-shaped columns of SN490B steel, the difference being that the web depth-to-thickness ratio (=49) of the last specimen was higher than that (37) of the first two specimens. The remaining two subassemblages (Specimens HBC-12 and HBC-16) used built-up box columns of SM570M steel; the wall width-to-thickness ratios were 12 and 15.7, respectively. The same built-up I-shaped beams of SN490B steel with a Reduced Beam Section (RBS) were used for all five subassemblies. A constant axial compression force ranging from 20 and 40% of the column yield force was applied to the column; the top end of the column was cyclically loaded with a sequence of increasing lateral drifts. Test results showed that the realistic boundary condition at the top end of the first-story column significantly altered the moment distribution along the column height; such distribution was further affected by the column buckling at the bottom end. The H-shaped columns experienced much significant local buckling and axial shortening than the built-up box columns. The highly ductile member requirement in AISC 341 cannot assure a satisfactory seismic performance of the two H-shaped columns at a story drift angle of 0.04 rad, which is not the case for built-up box columns.falseBuilt-Up Box ColumnColumn Inflection PointH-Shaped ColumnHigh-Strength SteelTwo-Story Subassemblage Frame Testjournal article2-s2.0-105027837025