NUMERICAL ANALYSIS FOR ASEISMIC BEHAVIOR OF BOTTOM STRENGTHENED I-SECTIONAL CONCRETE FILLED STEEL TUBE COLUMNS

In order to study the mechanism of the I-sectional concrete filled steel tube (CFST) column subjected to compression-bending load and further determine its aseismic performance index, a bottom strengthened I-sectional CFST column was proposed, whose flanges close to the bottom of the column were welded with enhancing steel plates. Based on the experimental results, the factors affecting the load-bearing capacity were analyzed. By means of finite element analysis software ABAQUS, the analysis to simulate numerically the specimens with different compression ratios, different strength grades of concrete, different heights and thickness of bottom strengthened steel plates were carried out. The analytical results were compared with the experimental results. The study shows that: the load-bearing capacity and the ductility decrease when the axial compression ratio increases; the bearing capacity also increases with the strength grade of concrete, but its decline gradient steepens and the ductility decreases; when the height of the strengthened plate increases, the load-bearing capacity of specimens increases steadily, the energy dissipation capacity increases, and the ductility is approximately equal to each other; when the thickness of the strengthened plate increases, the load-bearing capacity improves only slightly. The I-sectional concrete filled steel tube column with bottom enhancing plates shows a better aseismic performance and higher energy dissipation capacity if suitable constructional requirements are satisfied. Such structural configuration can be adopted in the design of high-rise buildings.