Strengthening of Axially Loaded Circular RC Column under Close-In and Contact Blasts: A Numerical Investigation

Damage to the structure and loss of life due to increasing unintentional and terrorist explosions are grabbing the attention of engineers, planners, and policymakers. The damage to certain key elements of the structure, such as column, is fatal and irreparable and may lead to the collapse of the structure. Following the validation of experimentally tested square RC column with seismic lateral reinforcement carrying axial load subjected to an explosive charge of 100 kg ANFO (82 kg-TNT equivalent) at a scaled distance of 1.00 m/kg^1/3 with 10 mm mesh size using ABAQUS/CAE software equipped with concrete damage plasticity model with strain rate effect, equivalent circular columns to the experimentally tested one having seismic circular transverse reinforcement carrying the same axial load under the blast are considered. With the aim of dissecting the impact of blast on the RC columns, a high-fidelity physics-based numerical model has been developed subjected to equal peak pressure of 8.71 MPa in close-in and contact blasts. To improve the response of the column, different types of retrofitting techniques, including UHPC and UHPFRP coating, and CFRP wrapping are considered. Blast performance in terms of maximum displacement, damage dissipation energy, and compressive stress in concrete are compared and discussed. The results indicated that the strengthening with UHPFRC is comparable to CFRP wrapping in the case of the close-in blast; however, CFRP wrapping is found to make the column give excellent performance in both close-in and contact explosion loadings.