Blast Effects & Damage Assessment Flashcards

What is the term for the secondary phase of a blast wave where air pressure drops below ambient atmospheric pressure?

Answer: Negative phase

The negative phase (suction phase) follows the positive phase and can cause structures to be pulled outward after the initial push.

Which factor MOST significantly increases the scaled distance when assessing blast damage potential?

Answer: Increased standoff distance

Scaled distance (Z = R / W^(1/3)) increases as standoff distance R increases, indicating lower blast damage potential.

A structure experiencing 'progressive collapse' after a blast has failed primarily due to which mechanism?

Answer: Loss of load-bearing columns removing support for upper floors

Progressive collapse occurs when the loss of key load-bearing members causes successive floor failures in a chain reaction.

In the context of explosion injuries, which organ system is MOST vulnerable to primary blast injury?

Answer: Air-containing organs (lungs, GI tract, ears)

Primary blast injury results from the pressure wave acting on gas-filled organs, with the lungs and eardrums being most susceptible.

What does the 'impulse' of a blast wave measure?

Answer: The area under the pressure-time curve

Impulse is the integral of overpressure over time and determines the total force imparted to a structure or body.

When a blast wave travels from soil into an above-ground structure, the transmitted pressure is affected by:

Answer: Impedance mismatch between the soil and structural material

Impedance mismatch between media governs how much blast energy is transmitted, reflected, or absorbed at an interface.

Which window glass condition provides the GREATEST fragmentation hazard at a given standoff distance?

Answer: Annealed glass without any film

Annealed (ordinary) glass without film shatters into large, sharp fragments that travel at high velocity and cause severe laceration injuries.