Similarity study on lateral impact model of CFST column under high temperature

This paper develops a finite element model of circular concrete-filled steel tube (CFST) columns subjected to combined high temperature and lateral impact using ABAQUS through sequential thermal-stress coupling analysis, static analysis, and explicit dynamic methods, and validates it with existing experimental data from fire resistance tests and impact tests. Subsequently, based on the similarity theory of temperature fields, the heating curves for the reduced-scale circular CFST column models were designed. Meanwhile, using the dimensional system consisting of impact velocity, dynamic stress, and impact mass (V-σ_d-G), an impact similarity criterion was established, and the scaling factors for key physical quantities that are closely related to the impact response were derived. After that, numerical simulations of lateral impact on the reduced-scale models were conducted at different temperatures to design reduced-scale models whose thermal-mechanical coupling response characteristics closely approximate those of the prototype structure under strain rates below the transition strain rate. Furthermore, based on the simulation results, the response differences between the reduced-scale models and the prototype, as well as the reasons for these differences, were analyzed in detail. Finally, the velocity scaling factor was derived using the strain rate-dependent constitutive equations of steel and concrete to modify the reduced-scale models, which effectively reduced the error of the reduced-scale model in predicting the prototype response.