Mechanical Behavior And Engineering Application Of Special-shaped Column Composed Of Concrete-filled Square Steel Tubes

Among CFT members, concrete-filled square tubes (CFST) are more and morepopular nowadays. The special-shape CFST (SCFST) columns are composed ofseveral concrete-filled square tubular columns connected by connection plates. TheSCFST columns are suitable for the construction of residential buildings by utilizingthe advantages of both special-shaped sections and concrete-filled square tubularcolumns. In order to reduce structural self-weight, L-shaped section is a prior optionfor designers. In this paper, the construction, axial loaded behavior, eccentriccompression loaded behavior, and the seismic behavior of SCFST column has beenstudied.Two kinds of bolt connection modes and one kind of welding connection mode ofthe SCFST column were presented in this paper. The static performance of these kindsof constructions was compared using ANSYS software. According to the analysis, theplate welding construction was considered as the best than the other constructions.Additionally, the construction of vertical stiffener joints of SCFST column was alsopresented.In order to study the axial loading behavior of SCFST columns, one specimenwith concrete and one without concrete were compared in the test. The experimentalresults were compared with the results from finite element analysis. The experimentalresults and the comparisons indicated as follows: The plate welding construction wasvery reasonable, the collaboration of each mono column could be guaranteed by theconnection plate, and the infilled concrete improved the behavior of the SCFSTcolumn. The connection plate could be simplified to lateral and declinate lacing bar.The eccentric compression loaded behavior of SCFST columns was also studiedthrough test, in which two specimens were tested under one-way or two-way eccentriccompression loaded. The experimental results were compared with the results fromfinite element analysis. The experimental results and the comparisons indicated asfollows: The effect of the eccentric compression loaded angle on the behavior ofcolumn was very small. The connection plate could be simplified to lateral anddeclinate lacing bar.Additionally, this paper experimentally investigated the behavior of SCFSTcolumn subjected to a constant axial load and a cyclically varying flexural load. Theeffects of both the axial compression ratio and the length to width ratio on the behavior (stiffness, strength, ductility, and energy dissipation) of SCFST columnswere studied. The experimental results were compared with the results from finiteelement analysis.The experimental results and the comparisons indicated as follows:The seimic behavior and energy dissipation of the SCFST column was very good. Theconnection plate could be simplified to lateral and declinate lacing bar.The failure mode and bearing capacity obtained by finite element analysis agreedwith those obtained by test. So the finite element analysis was an effective way tosimulate the behavior of SCFST columns.Finally, based on the MIDAS software, the design method of SCFST structure waspresented and the behavior of the structure was also studied. The detailedconstructions were presented. The analysis results indicate that the SCFST structuremeet the seismic demand and the performance of it is better than CFT in rarely metearthquake.