Performance of high-strength concrete filled high-strength steel tubular columns under explosive loading

High-strength concrete filled high-strength steel tubular (HCFHST) columns are increasingly used in engineering applications. However, during service, these columns may be exposed to explosive loading, which can significantly affect their structural safety. This study investigates the close-in explosion behaviour of HCFHST columns through field tests and validated numerical simulation. Seven HCFHST columns were tested under explosion distances ranging from 0 to 150 mm, and their failure modes, as well as the time histories of acceleration and pressure, were recorded and analysed. Three distinct failure patterns of HCFHST columns were identified, namely rupture failure, crater failure, and cracking failure. Finite element (FE) models were subsequently established and validated against the experimental results, enabling further analysis of full-range motion, stress wave propagation, damage mechanisms and energy absorption of HCFHST columns. A parametric investigation was then performed to assess the influences of TNT charge weight, steel ratio, cross-sectional diameter, steel strength, and concrete strength on the explosion-resistance capacity of HCFHST columns. The results indicate that explosion energy is mainly consumed by local denting deformation under close-in explosive loading. Meanwhile, increasing TNT charge weight leads to more serious local damage of the column, whereas higher steel ratio, larger cross-sectional diameter, and greater steel strength effectively reduce both peak acceleration and crater depth. Finally, an empirical formula was developed to predict the local crater depth of HCFHST columns under close-in explosive loading. • Blast testing and numerical simulation. • Full-range motion, stress wave propagation, damage mechanism, and energy absorption. • Effects of TNT charge weight, steel ratio, cross-section diameter, steel yield strength, and concrete compressive strength. • Prediction of local crater depth using dimensional analysis.