Finite Element Analysis of Self-Compacted Concrete Filled Steel Tube Columns Exposed to High Temperatures

To represent the structural behavior of self-compacted concrete filled steel tube composite columns under axial compression loading after high temperatures exposure, a nonlinear three dimensional finite element analysis model has been achieved to analyze these columns using ANSYS R-15 software. An eight-node solid brick element (Solid65) is used to represent the concrete, while a four-node isoparametric shell element (Shell63) is used to represent the steel tube for the analyzed composite columns. A Newton-Raphson incremental-iterative approach is used to simulate the nonlinear solution technique. The finite element method results indicated that the predicted ultimate loads and axial deformations for the analyzed four column specimens agree well with the experimental results for normal strength and high strength concrete in static loading up to failure, and therefore, it is sufficient to model how these columns behave. The reduction in the analytical ultimate loads compared to the experimental values ranged from 11% and 16%, while the reduction in the total axial deformation values ranged from 3% to 7%. The yield patterns obtained from the analyzed composite columns under axial compressive stress are comparable to the yield patterns determined from the experimental study.