REVIEW COLLAPSE MECHANISMS CAUSING DAMAGE FROM CONTROLLED AND UNCONTROLLED DEMOLITIONS

Abstract

To design for blast, ballistic or seismic loadings an engineer needs to know the collapse mechanisms of all forms of typical building systems whether residential or commercial in order to have the technical capacity to design against such loadings. Once the engineer becomes aware of the collapse mechanisms that are likely to cause damage through blast loadings that will be applied to a structure by a controlled demolition or an uncontrolled demolition (terrorist attack), a position is reached whereby the design process can commence to not only accommodate the overpressures but also, through design, inhibit or delay collapse so those caught within the building can escape to safety before total collapse occurs. In most such cases death or injury occurs primarily because of the collapse of structures and not because of blast, ballistic or seismic loadings applied to it. In most building systems there are structural entities that are present for specific structural reasons but nevertheless are problematic in that they can inhibit progressive collapse. These problematic structural entities need to be understood in detail and addressed both in controlled and uncontrolled demolitions to be able to achieve a progressive collapse. 3rd world countries see most buildings damaged by the blast, ballistic and seismic loadings as design standards either don’t exist or are not policed by local government instrumentalities thus leading to excessive damage, death or injury.