Performance of seismically designed buildings under blast loading

Structures, seldom designed with adequate safety to blast hazards, are often designed for earthquake. At this backdrop, presented herein is an attempt to achieve safety against explosive hazard through aseismic design methodology. The possibility of blast damage to ‘solitary’ structures appears to be comparable to that due to earthquake beyond a critical standoff distance of explosion. The study develops an equivalency of blast parameters (charge weight, critical stand-off distance) and earthquake characteristics (PGA) along with ductility capacity (represented by R) so as to yield similar damage. For example, beyond a critical stand-off distance of about 25m, structures designed elastically for earthquake with PGA of 0.2g may endure little damage (similar to that at R = 2 during earthquake) due to the explosion of 500 kg charge-weight. This not only helps to ascertain the level of safety of seismically designed buildings under blast, but also to decide the distance of fencing to be constructed to protect an important structure in accordance with their functionality. However, the response in an urban setting due to similar blast action may be relatively subdued. The detailed results presented in the study may be useful to prepare codified load combinations to mitigate blast hazard.