Applied Knowledge

Four Critical Characteristics Of Blast Waves

An explosion is a rapid release of energy in the form of light, heat, sound, and a shock wave.   From a protection perspective, the shock wave is what we are most concerned about.   However, as a security professional or an architect, or a procurement official, you may be asking yourself, why do I care?   Well, you really don’t.  What you care about is how this shock wave affects people and property and how to best mitigate the potential hazards.   In order to better understand the hazards and mitigations, it is useful to understand some of the fundamental characteristics of the shock waves.   The following are some of the primary characteristics that are of interest:
  • The shock wave expands outwards in all directions.  Which means that just because you aren’t the target does not mean that your building won’t be damaged.  So whether the target is across the street, around the corner, or two blocks away, there will be some effects on your building and it’s occupants.
  • The duration of the shock wave is very short, measured in milliseconds rather than seconds (think of a blink of the eye), and the energy imposed on anything it its path are enormous – many times greater than hurricanes.  The short duration gives engineers a fighting chance to develop designs of new buildings and retrofits of existing buildings to resist the enormous energy.  The short duration allows engineers to design blast resistance buildings differently than buildings only subjected to more continuous loads such as gravity, so not all blast resistant buildings need to end up looking like bunkers.
  • The energy of the shock wave decreases exponentially with distance.   This means that every foot (or meter) counts, especially closer to the detonation.   So if you are laying out a new building or compound, think carefully about where explosive attacks might come from, and locate your occupied buildings as far as possible from those locations.
  • The amount of energy imposed on a person or structure is dependent on the angle at which the shock wave hits.  A straight-on (or perpendicular) approach transfers more energy than a parallel approach, this is one of the reasons that bomb damage can often look like a bite was taken out of the building.   As you go farther down (or up) a building from the detonation, the angle gets closer and closer to parallel, thus decreasing the amount of energy imposed on the building elements.
Again, why do we care about these characteristics?  Because they translate to how be smart about increasing protection.
For information like this, and more, check out our upcoming face-to-face course:  Protective Knowledge – Protection In High Threat Environments.

Richard Galli, PE Becomes Associate Principal and Co-Owner of Stone Security Engineering

New York, New York (March 22, 2016 ) – Stone Security Engineering, P.C., the woman-owned small business specializing in protecting people and property from accidental and manmade hazards, announced today that Mr. Richard Galli, PE is now an Associate Principal and co-owner of the company.

“This is a major milestone for Stone, and moves us one step closer to our goal of sharing ownership with our core team of dedicated engineers.  Richard is a talented engineer who brings a fantastic client-focused excellence to the team.   This translates to high quality analysis and successful projects for all involved.  I am incredibly pleased to have Richard join us in ownership.”  Hollice Stone, President and Founder

Mr. Galli  brings an impressive breadth of experience in the fields of security and safety design to the firm. His recent projects have included a new Veterans Administration Medical Center, an existing IRS facility, an international NGO compound in Helmand, Afghanistan, blast testing of innovative materials and building element configurations, and detailed design and analysis of doors, windows, and curtainwalls.  Rich has participated in more than 100 successfully completed projects related to blast, progressive collapse, and fragment evaluation and mitigation for government and industrial sector clients. The scope of these new construction or retrofit design projects has ranged from feasibility studies and conceptual designs to detailed design and construction administration support.  Richard received his Bachelor and Master of Science degrees in engineering from George Washington University in Washington, DC in 2006 and 2011, respectively, and is a licenses Professional Engineer in Virginia and New York.

Stone Security Engineering remains a small woman-owned business, even with our expanded ownership structure.

Stone Security Engineering, P.C., is an internationally recognized specialty engineering consulting business with offices In New York City and Washington, DC with focus on blast resistance, security and safety engineering and design, predicting and mitigating hazards from explosions, fires and toxins; assessing security and blast vulnerability; research and development, testing and training. Our engineers have participated in multi-hazard vulnerability, threat, and risk assessments for more than 200 facilities around the world and abnormal loading design for more than 300 buildings and structures. The company’s web site ( contains more information.

WeWork ‘Creator’ Article

I want to thank WeWork ‘Creator’ Magazine for writing such a nice article on us.   Check it out here