Blast loading influence on load carrying capacity of I-column

• Newly developed multistage analysis procedure was used for capacity assessment.
• Coupled ALE algorithm was applied to simulate blast wave interaction with structure.
• Multistage analysis with different algorithms showed to be very effective.
• Large deformation of structure caused only 10% reduction of carrying capacity.
• Separation between web and flanges caused significant loss of carrying capacity.

The paper presents the multistage numerical analyses procedure for a load carrying capacity assessment of a blast loaded I-column. The procedure determines the ultimate axial load in four stages: static preload, dynamic blast loading, dynamic response after blast loading and a static load carrying capacity assessment of a deformed structure. Preload and assessment of the ultimate axial load were performed using static Newton–Raphson algorithm. Consequently, two dynamic cases were analysed using a commercial code with an explicit integration procedure (central difference method), where the blast load was simulated using Lagrangian–Eulerian domain coupling. The developed method proved to be a very efficient way to assess the load carrying capacity of a column with imperfections caused by dynamic, blast loading. The results of analyses indicated that the column (HKS-300 cross-section) is very resistant to blast loading. High deformation of its structure (close to ultimate strains) caused only 10% reduction of the load carrying capacity. Separation between a web and flanges of the I-column was the only factor that caused the significant loss of carrying capacity. Moreover, not only the mass of a charge influences the structural behaviour but also the explosive shape as well as the initiation point of detonation can significantly change the level of structure damage. Initiation point of detonation at the back of HE heavily increased blast pressure during interaction with the structure and a cylindrical shape of the explosive also increased the energy absorbed by the column. On the other hand, the use of the spherical charge or frontal detonation significantly reduced the destructive capabilities of the explosives.