Protective Design for Columns Against Close-in Blast Effects

Close-in blast effects can cause catastrophic damage to both steel and reinforced concrete (RC) columns. Moreover, a large size column may not inherently afford much more protection than a small one for close-in charges. This paper describes issues that must be addressed in the design of RC columns to resist blast loads, especially those generated by nearby or in-contact detonations. Also shown are results from experiments showing the sorts of protective-design concepts that have proved effective in insuring the survival of RC columns subjected to the close-in blast loads. In particular, for close-in blasts, determining the effectiveness of a particular column design requires developing an effective means to consider the damage imparted to the concrete by the shock front and to assess the remaining capacity of the column given this damage. Another major aspect in realizing a protective design for columns is assessing the vulnerability of the support provided at the column's base, which may be severely damaged by a close-in blast. To facilitate the design of RC columns for such situations, a new class of simplified design and analysis tool was developed, which is described in the paper.