Numerical Study of Damage Modes and Damage Assessment of CFST Columns under Blast Loading

Columns of frame structures are the key load-bearing components and the exterior columns are susceptible to attack in terrorist blasts. When subjected to blast loads, the columns would suffer a loss of bearing capacity to a certain extent due to the damage imparted, which may induce the collapse of them and even cause the progressive collapse of the whole structure. In this paper, the high-fidelity physics-based finite element program LS-DYNA was utilized to investigate the dynamic behavior and damage characteristics of the widely used concrete-filled steel tube (CFST) columns subjected to blast loads. The established numerical model was calibrated with test data in open literatures. Possible damage modes of CFST columns under blast loading were analyzed, and the damage criterion based on the residual axial load capacity of the columns was adopted to assess the damage degree. A parametric study was conducted to investigate the effects of critical parameters such as blast conditions and column details on the damage degree of CFST columns. Based on the numerical simulation data, an empirical equation was proposed to estimate the variation of columns damage degree with the various parameters.