Mechanics Performance Analysis Of Thin-Walled Square New Concrete-Filled Steel Tubular Short Columns

With the use of thin-walled steel tube in concrete-filled steel tube engineering, both the amount of steel consumption and engineering cost can be reduced. In addition, the material property can be taken full advantage of. In fact, for the high-rise buildings, breadth (diameter)-to-thickness ratio of the steel pipe wall in columns'cross section is within the limit of that of the thin-walled steel tube because of large sectional size of the columns in the ground floor. Therefore, it is of universal significance to study this problem. Considering the breadth (diameter)-to-thickness ratio is greater, local buckling of the steel wall may generate before it reaches ultimate bearing capacity. The capacity of concrete-filled steel tubular short columns won't have the anticipated effect under the combination of two materials. In order to delay or avoid local buckling, and to improve stability and application of structure, it is an effective method to study a reasonable construction measure.To have the purpose of improving the overall deformability of specimens, research situation and engineering application of concrete-filled steel tubular short columns in home and abroad are summarized. Then, a new construction method relating to embed long or short binding rebars to the inside of specimens is studied to resolve the problem of local buckling. Based on the experimental research, both the load mechanics and property of specimens and effect of the binding rebars are studied by calculating and analyzing the established mechanical model. Then, the two results are compared. By theoretical analysis, the effect of bingding rebars is confirmed and quantitative ductility factors are given. Also, influences of wall thickness, form of binding rebars, concrete strength to bearing capacity and deformability of specimens are analyzed.The results show that the main factors affecting the bearing capacity are steel pipe wall thickness, concrete strength, binding rebars in turn and the ductility is concrete strength, binding rebars, wall thickness. Long or short rebars significantly improve the deformation properties of specimens. Taking the common specimens' average ductility factor of 2.30 as a benchmark, the average factor of specimens configured with short rebars is 2.85. increased by 24% and configured with the long is 3.34. increased by 45%. Deformation properties of the specimens substantially increase and security of the structure enhances after setting up rebars.The theoretical analysis of local buckling and the bearing capacity problem of thin-walled square concrete-filled steel tubular short columns is presented in this paper. Also, further research on mechanical properties of concrete-filled thin-walled square steel tube short columns such as ductility is made. Finally, it can be a reference for engineering design and application.