Study on explosion-resistance performance of concrete-filled steel tubular columns considering the influence of elevated temperatures

Fire and explosion often occur together that seriously threatens the safety of engineering structures. In order to investigate the explosion resistance of concrete-filled steel tubular (CFST) columns at elevated temperatures, the finite element (FE) model of explosion resistance performance for circular CFST columns at elevated temperatures was established using the ABAQUS software. The fire and blast loads were simulated using ISO 834 standard fire and ConWep model, respectively. In the model, the static implicit and dynamic explicit analysis was coupled using “Restart” and “Import” commands and the strain-rate effect was considered. The experiment results of related literatures, including the temperature field, fire resistance duration and explosion resistance of CFST columns, were used to verify the feasibility of the method. Based on the validated FE models, the explosion mechanism of CFST columns subjected to standard fire was analyzed, including the failure modes, full-range analysis, development of stress and strain, interaction between steel tube and concrete and energy consumption. The influence of duration time, material strength, steel ratio and explosion equivalent on the explosion resistance were studied. The maximum mid-span deflection (Δpeak) was employed to quantitatively analyze the explosion-resistance performance of the CFST columns. The results show that shear failure firstly occurs at both fixed ends, and then the whole column presents flexural failure mode when subjected to explosion load under fire condition. With the increase of duration time, the proportion of energy consumption of steel tube decreases, and plastic deformation of concrete gradually becomes the main energy consumption mechanism. The concrete strength, explosion equivalent and axial load ratio have significant influence on the explosion resistance of CFST at high temperatures. After 0 min and 90 min fire duration, the explosion resistance is improved by approximately 21% and 42% respectively when the concrete cubic compressive strength increases from 30 MPa to 50 MPa.