Research On Mechanical Behavior Of Short Columns And Slender Columns Of High Strength Concrete-Filled Square Steel Tubular With Inner CFRP Circular Tube Under Eccentrically Compression

In practical project, because the concrete-filled square steel tubu columns have great ability to anti-bending, especially have simple type of node and easy to decorate, many design and builders like to use this type of structures very much. But compared with round cross-section steel tube confined concrete structures, the square cross-section of steel confined concrete structure restrains the core concrete in the cornor. This paper is based on this problem and put a new material which was known for its feature of lightweight and high strength to overcome the shortcoming.Then a new type of structure was gotten——columns of high-concrete filled square steel tubu with inner CFRP circular tube,CFRP tube were put into high-concrete filled steel square tubu column,the core concrete in the column was divided into two parts: sandwich concrete and inner concrete.This paper used the ABAQUS finite element analysis to carry out the nonlinear finite element analysis on short columns and sender columns under uniaxial eccentric compression. Finite element models were established by considering the effects of material nonlinear constitutive relationship and the contact relationship of high-concrete, CFRP, steel tubu.And then compared with the result of experiment.At last it was revealed the mechanical behavior of short columns and sender columns under uniaxial eccentric compression .Then the models were change various paramenters as the number of CFRP layers, steel ratio, eccentricity ratio, slenderness ratios and so on.Finally it was got the discipline of the static performance of the short columns and sender columns of high-concrete filled square steel tubu with inner CFRP circular tube under uniaxial eccentric compression with each parameters changing.Some valuable conclusions were drawn in the paper in researching the short columns: ultimate bearing capacity of concrete-filled square steel tubu with inner CFRP short columns are a little higher than concrete-filled square steel tubu short columns under uniaxial eccentric compression. and the midspan displacement of columns with inner CFRP is much shorter than the common columns of high-concrete filled square steel tubu.Even the inner CFRP tubu has significant effect on its ductility to concrete-filled square steel tubu with inner CFRP short columns after load-displacement curves passed the highest point. The research shows that short columns under uniaxial eccentric compression of high-concrete filled square steel tubu with inner CFRP circular tube is efficient of getting high ductility and the deformation is markedly improved compared with the common columns of high-concrete filled square steel tubu.Some valuable conclusions are drawn in researching the sender columns: ultimate capacity between concrete-filled square steel tubu with inner CFRP sender columns and sender columns without inner CFRP under uniaxial eccentric compression is almost the same, and the contribution of CFRP tube to ultimate bearing capacity of the specimen is negligible.It is shown that the ductility of mediun slenderness ratio culumns are improved markedly in researching the midspan displacement of the sender columns .