The rise in the number of terrorist attacks over the past few decades has led to growing concerns about the performance of buildings designed by well-established conventional design methods under blast loading. The concerns arise from the response of buildings and loss of lives in some of the more popular terrorist attacks such as those involving the Alfred P. Murrah Building, the Khobar Towers, and Marriott Hotel in Islamabad. Whereas most damage during these attacks was to non-structural elements such as infill wall systems and window glass, the collapse of the Alfred P. Murrah Building revealed that failure of load-bearing members can lead to widespread buildings failure. Thus, it has become imperative to investigate the performance of load-bearing building members to blast loading. More specifically, to quantify the blast resistance offered by buildings designed and detailed for other load types such as wind and earthquake.The effect of seismically detailed reinforced concrete columns on their blast resistance was investigated. Reinforced concrete columns not forming part of the seismic force resisting system were detailed according to CSA A23.3-04 -Design of Concrete Structures. The detailed reinforced concrete columns were subjected to blast loading in a numerical study using the high fidelity physics based finite element code (LS-DYNA). The numerical study was undertaken to investigate the effects of columns designed for different levels of seismicity in the National Building Code of Canada (NBCC) on their blast resistance.The results of the numerical study show that the lateral reinforcement detailing has a significant effect on the behaviour of columns under blast loading. When the reinforced concrete columns were detailed for high levels of seismicity by reducing the lateral reinforcement spacing in the plastic hinge region, the maximum lateral displacement was observed to reduce significantly in comparison with columns detailed with lateral reinforcement spaced for conventional design.ii Also, reducing the lateral reinforcement spacing at mid-height of the column, where plastic hinge formations is expected under blast loading, further reduced the maximum lateral displacement.The closely spaced lateral reinforcement in the seismically-detailed columns was observed to increase the blast resistance, especially to close-in blast loading.The effect of axial loading was also investigated in the numerical study. As the axial load ratio increased, the blast resistance of the concrete columns increased. However, at high, axial load ratios, the columns suffered concrete crushing in the compression zone leading to higher lateral displacements and instability. At higher scaled distances, increasing axial load ratios resulted in reduced maximum lateral displacements; with the seismically-detailed columns not offering any significant advantage over the conventionally-detailed columns.iii