Finite element analysis of the flexural behavior of square CFST beams at ambient and elevated temperature

[EN] This paper presents the finite element (FE) analysis and modeling of square concrete-filled steel tube (CFST) members subjected to a flexural load at ambient and elevated temperature. The commercial FE tool ANSYS was used in the 3D modeling taking into consideration material and geometric non-linearities. The developed FE model can accurately predict the ultimate moment capacity of the square CFST members subjected to flexural loads and fire resistance time. A parametric study is conducted using the verified FE model to study the effect of the compressive strength of infilled concrete and the yield strength of the steel tube on the flexural behavior of the square CFST members. The ultimate bending capacity of the CFST members increases by up to 27% when the yield strength of the steel tube increases from 210 MPa to 400 MPa while its fire resistance time decreases. For a D/t ratio equal to 30, the flexural capacity increases by 20% when the compressive strength of the infilled concrete increases from 60 MPa to 100 MPa, while it shows increase in fire resistance time.