Security Risks and Safety Hazards for Building Facades

Building facades in commercial and residential buildings in Australia, UK and elsewhere are highly vulnerable to terrorist threats involving explosive blast loading. The modelling of consequences to built infrastructure when subject to blast loading is well developed; however, considerable uncertainty remains with respect to system response and explosive loading parameters. In this paper, structural facades are assessed with a focus on glazing as this is a structural and load-capacity system that poses significant safety hazards when effected by explosive blast loads. A new computational tool that undertakes a probabilistic risk assessment procedure is developed to predict damage and safety hazard risks following blast loading of glazing. The software tool is called "Blast-RF" (Blast Risks for Facades). The structural reliability analysis uses stress limit states and the UK Glazing Hazard Guide's rating criteria to calculate probabilities of glazing damage and safety hazards conditional on a given blast scenario. The reliability analysis considers the variability of explosive material energetic output (pressure, impulse) glazing stress limit, fragment drag coefficient, glazing dimensions, stand-off distance and explosive weight. This allows the prediction of likelihood and extent of damage and/or casualties; information which will be useful for risk mitigation considerations, emergency service's contingency and response planning, collateral damage estimation, weaponeering and post-blast forensic analysis.