Blast protection: Optimised engineering

Specialist engineer Guido Lori explores how bomb-blast-resistant façades are the new safety standard and how precision engineering is enabling Permasteelisa Group to integrate advanced blast technology into next-generation façades without compromising architectural vision or carbon-reduction goals.

Geopolitics have brought unpredictable threats to public safety in our built environments, including a rise in Improvised Explosive Devices (IEDs). In increasingly dense urban centres, an explosion puts every surrounding building at risk, and bomb-blast-resistant façades, once reserved for government HQs and embassies, are fast becoming a standard future-proofing requirement for all landmark developments.

When a blast occurs, the façade is the building’s first line of defence. It must absorb and dissipate immense shock-wave energy through rapid movement or intentional buckling to minimise overall damage, and crucially protect the lives inside.

The compliance trap

When mitigating blast risk, many developers and architects default to standard regulatory frameworks, such as the National Protective Security Authority (NPSA) guidelines. While these frameworks provide essential baselines, following them as a design manual can result in a costly over-specification of materials, involving more steel, thicker glass, and heavier framing.

Optimisation: balancing aesthetics, sustainability, and security

Our approach to designing blast resilient bespoke curtain walls rests on Multi-Degree-of-Freedom (MDOF) systems – using precise calculations to predict real-world façade behaviour. By leveraging accurate technical data, we can design thinner, lighter profiles that considerably reduce embodied carbon compared to traditional blast-resistant specifications, at the same time as validating a façade’s ability to intelligently handle extreme dynamic loads.

This engineering performance-based approach means that we can strike an important balance between architectural scope and protection levels, to make a blast-enhanced façade compatible with design features including openings and glass fins. For example, by precisely controlling the opening direction, capping the maximum opening angle, deploying multiple skins and utilising localised hardware strengthening, we can integrate operable openings into even a ‘maximum threat’ façade.

Material science and dissipative components

An explosion releases chemical energy that expands hemispherically, and materials behave wildly differently under these extreme dynamic loading rates. Our engineering approach balances three factors: maintaining the structural integrity of framing members, mitigating the hazards of flying glass, and minimising the load transferred to the primary building structure. To achieve this however, all components must be modeled simultaneously to capture their complex mutual interactions.

Whole-system modelling and testing

To move beyond standard codes, which treat elements in isolation, our in-house platform Testudo captures the dynamic interaction between the glass, framing, and bracketry as a unified, whole-system event. This custom-built software is built on a peer-reviewed methodology published in multiple conference papers and academic journals.

Testudo enables our teams to design highly realistic, cost-effective blast solutions across diverse typologies, including unitised façades, stick systems, cable structures, and Closed Cavity Façade (CCF) systems. Every system is custom-engineered and scalable to mid, high, or extreme threat profiles, and tested on request to meet recognised blast standards. We continuously calibrate our digital models using physical data, ranging from component-level material testing to full-scale blast testing on complete façade units.

Novel components

To take the brunt of an impact away from the glazing or the main concrete slabs, we have also developed a patented Dissipative Bracket, an innovative component that remains rigid under day-to-day wind loads, but is engineered to ‘crash’ under the extreme impulse of a blast wave. By allowing the bracket to absorb and dissipate the energy through controlled deformation, it mitigates transfer to the primary building structure and catastrophic glass failure.

R&D partnerships

Alongside our in-house specialist engineers who work in this field, and input directly to our projects, we maintain long-term partnerships with global universities to ensure our designs are based on the most advanced academic research and material science available. This includes:

• Imperial College London (UK): Researching the high-strain properties of interlayers and frame materials.
• HafenCity University Hamburg (Germany): Advancing the understanding of glass design strength and dissipative bracket testing
  The University of Melbourne (Australia): Exploring glass post-cracking behaviour, structure-medium interactions (aero-elastic damping), and laminated glass failure modes.
• Cranfield University (UK): Investigating interlayer shear relaxation under extreme loads.
• University of Technology Sydney (Australia): Analyzing thermally broken profiles.
• TU Dresden (Germany): Investigating interaction between façade and building structure under blast loads.

The business case

An optimised blast-resistant façade is a long-term commercial strategy that drives value throughout the lifecycle of an asset. Engineering a building to dynamically absorb blast energy significantly lowers its risk profile, which is directly recognised by insurers through reduced premiums over the long-term.

During the UK financial district bombings of the 1990s, the highest financial losses stemmed from business disruption rather than structural collapse. An optimised façade limits structural damage during an incident, protecting the asset, and most importantly lives. It also means that business operations can be resumed effectively.

Global leaders

Using our leading technology, to date we have successfully designed, manufactured, and installed over 50 major blast-resistant façades worldwide, including some of the most iconic and high-security architectural landmarks, including:

• New York: One Vanderbilt, Hearst Tower, Hudson Yards, 3 World Trade Center, LaGuardia Airport, and One Bryant Park.
• London: Salisbury Square, London Wall Place, Bloomberg HQ, 99 Bishopsgate, 52 Lime Street (The Scalpel), and 8 Canada Square.
• Global Landmarks: KL118 (Kuala Lumpur), Lex 2000 (Brussels), Paris Courthouse (Paris), the US Embassy (Beijing), O’Hare International Airport (Chicago), Commonwealth Law Courts (Melbourne), and The Central Government Offices (Hong Kong).

To find out more about moving beyond compliance, to intelligent, optimised engineering, please get in touch at g.lori@permasteelisagroup.com.