The Threat

“Buildings have long been a target for terrorist attacks. Long before the devastation of the World Trade Centre on 9/11 terrorist groups have used explosive devices to cause large numbers of casualties, damage or destroy buildings and interrupt business operations. Their targets include crowded public spaces, such as shopping malls or sporting venues, financial institutions, energy and utilities providers and transport systems.

“The key threats are vehicle-borne explosive devices, which can deliver enough explosive to damage or destroy a building when detonated beneath or immediately adjacent to the target; and smaller explosive devices concealed in backpacks and suitcases or in parcels, which aim to attack people rather than structures, causing injury by the blast itself and fragments such as nails and broken glass.”

Global Building Response to Blast Loading  Finite Element Analysis

Our Role

“We provide specialist blast analysis as part of the structural design team, also working closely with our colleagues in security and facades in an integrated effort firstly to protect the building from attack and then to minimise the impact of an attack should preventative measures fail.

"We are experienced in the analysis of blast waves and their interaction with the built environment. We can simulate the detonation of a device in a building or cityscape to analyse the effect of the resulting blast wave on the structural elements of buildings such as columns, beams, slabs and glazing. We can also estimate injuries to people located in areas affected by the event. Our work either forms part of the core structural delivery on a project, or we can provide a standalone service to clients as part of their security assessment documentation.

 “The first task is to undertake a threat and risk assessment to help the design team understand the potential risks associated with the building. Then we generate a model to represent the geometry of the building and what happens to the structure when the charge is detonated. This allows us to calculate the loadings according to different types of explosion and under different scenarios, assess the effects of column removal to determine whether this would cause disproportionate collapse, identify key areas for enhancement and ensure the appropriate robustness measures are incorporated within the overall structural design.

“Our recommendations for reducing personal injuries would include requirements for the façade, such as the use of laminated glass in new buildings, or the addition of secondary glazing or anti-shatter film to the windows for the refurbishment of historic buildings.”

3D Blast Analysis  Blast Modelling using Computational Fluid Dynamics (CFD) Approach

Finding The Balance

“In most developments the probability of an attack is quite low, so it’s important to find the right balance between incorporating counter terrorism measures into our buildings and public spaces while maintaining quality of place and other design imperatives such as accessibility, costs of construction and operation, fire protection, energy efficiency and aesthetics. The best option is always to integrate the bomb blast requirements into the design as early as possible to obtain the most economical and least intrusive solutions.”

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