In the framework of continuum mechanics in three-dimensional setting a numerical finite elements method, modified to address the impact of the explosion and the tasks carried out solution to the problem of calculating the damage in concrete and reinforced concrete columns at undermining their lateral surfaces of cylindrical charges of open high explosive (HE). The action of the explosive charge in the column is modeled by the pulse loading. The destruction of concrete under dynamic loading is considered as a process of growth and coalescence of microcracks formed under the influence of stress during loading.