An Equivalent Loading Methodology for Postblast Modeling and Damage Assessment of RC Columns after Explosion Events

Research concerning blast-loaded reinforced concrete (RC) columns typically falls into two categories: preblast analysis with defined blast loads and postblast analysis based on diverse explosion-induced evidence. Among postblast investigations of RC columns, damage assessment after an explosion event stands as one of the burning issues. To facilitate postblast damage assessment of RC columns, this paper describes an equivalent loading methodology to establish the finite-element (FE) model of RC columns that have sustained blast damage. Initially, the equivalent loading methodology for the blast-affected RC columns is introduced, comprising two essential steps: (1) a linear correlation with a slope of 1.04 and an intercept of 15.99 mm, accompanied by the simplification of blast-induced vibration as the first damaged mode shape, was established for the estimation of the maximum deflection; and (2) the application of a velocity loading protocol characterized by the maximum deformation and the first damaged period. Subsequently, the FE modeling approach for the RC columns exposed to blast loads is detailed and verified through existing experimental results. The dynamic responses of RC columns under varied combinations of peak overpressure and resultant impulse are examined, whereby the linear correlation of maximum and residual displacement of the blast-affected RC column is confirmed for the estimation of maximum deformation. Ultimately, the robustness of the equivalent loading methodology is validated through a comparative analysis of damage contour, residual displacement, residual bearing capacity, and modal parameters of damaged RC columns given equivalent loading versus actual blast loading. The comparative analysis demonstrates that the proposed equivalent loading methodology possesses a maximum relative error of 18.2% when simulating the damage incurred by RC columns due to blast events.