RETROFIT OF REINFORCED-CONCRETE STRUCTURES TO RESIST BLAST EFFECTS

Analyses were conducted to demonstrate the effectiveness of jacketing columns of existing reinforced concrete multistory buildings to improv e their survivability to attacks by explosives. Different standoff dis tances, charge sizes, and steel and composite jackets were considered. Two building designs were analyzed: one in which the building members were designed primarily for gravity loads (UBC seismic zone 1) and on e in which the members were designed to resist seismic loads (UBC seis mic zone 4). Structural response predictions were performed with the t hree-dimensional Lagrangian finite element code DYNA3D, using a concre te material model especially designed to pi edict nonlinear concrete r esponses to explosive loads. The results indicate that jacketing can b e an effective means to retrofit an existing facility to lessen its vu lnerability to blast loads.