Dynamic behavior of concrete filled steel tubular columns internally strengthened with I-shaped CFRP against vehicular bombs

Square concrete filled steel tubular columns internally strengthened with I-shaped carbon fiber reinforced polymer (SCFST-CFRP) demonstrate promising potential for application in building structures, particularly in high-risk buildings and critical structural elements, due to their exceptional static and impact resistance. Highrisk buildings may be vulnerable to vehicular bomb attacks over their lifespan, resulting in blast loading. In this study, the blast resistance of SCFST-CFRP columns is investigated through field blast tests and numerical simulation. The plastic deformation of SCFST-CFRP members is low, and they exhibit promising blast resistance in explosion tests with a scaled distance of 0.07 m/kg1/3. Subsequently, SCFST-CFRP columns with varying steel ratios were designed according to specifications to investigate their deformation and damage under typical vehicular bomb scenarios. It was found that the blast resistance of SCFST-CFRP columns is superior to that of ordinary SCFST columns, particularly when the steel ratio is smaller. Additionally, a protection distance of 3.95 m (1.01H) is sufficient to ensure that the composite columns do not fail under these scenarios, highlighting favorable blast resistance for SCFST-CFRP columns. Based on the parametric analysis of 115 sets of data, a prediction formula for the critical failure distance of SCFST-CFRP columns under typical vehicular bomb scenarios is proposed. This study serves as a valuable reference for designing SCFST-CFRP columns with blast resistance.