Study On The Mechanical Properties Of Long Columns Of Concrete Filled Steel Tubes With L And T-shaped Cross Sections

In order to meet people's demand for architectural height,spatial layout and aesthetic individualization,the design of building structures urgently requires new components to meet the more demanding requirements of the market for its functionality and viewing performance.The special-shaped steel pipe concrete columns not only combine the ultra-high bearing capacity and deformation capacity of the steel pipe,but also combine the durability,stability and fire performance of the concrete.At the same time,its special cross-section form can satisfy the diversification of indoor layout to the maximum extent..Therefore,systematic research on L and T-shaped cross-section specimens has become a very necessary topic at present.At present,the study of concrete-filled steel tubular columns with special cross-sections is mainly focused on the study of various types of mechanical properties of short columns.Therefore,it is more important to study the stability of L-and T-shaped sections of concrete-filled steel tubes and long columns..Based on the verification model obtained by ABAQUS finite element software,this paper carries out the buckling analysis of the specimen under axial compression.The main tasks include:1.Firstly,the constitutive model of steel and concrete suitable for ABAQUS analysis is selected,and then the selection of component types,the constraint of boundary conditions,and the division of grid are performed.Finally,the model is established.Using the simulation data obtained and the corresponding experimental data for comparison,analysis and adjustment,the finite element analysis model with error controllable is obtained.2.Secondly,ABAQUS was used to expand the analysis: 15 sets of test pieces were designed to investigate the effects of five factors of concrete strength,steel ratio,length-to-diameter ratio,boundary condition constraints,and cross-section type on the test piece's stability.Including the linear buckling of the various modes for comparative analysis and the impact of the specimen in the nonlinear buckling failure of the elastoplastic stage of the load-deformation curve analysis of the law.Finally,the guiding theory applied in the design and construction of construction projects is obtained.3.Finally,the theory of solving the load-carrying capacity of concrete-filled steel tubes applied to European,American,and domestic departments was analyzed and studied.The results were obtained for the application of L-shaped and T-shaped concrete-filled steel tubes and long columns based on superimposed theory and quasi-steel theory respectively..And tofurther fit the test and simulation data,and ultimately laid the foundation for the formula to obtain ultimate bearing capacity.