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blast load and period of structure

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civil1980

Civil/Environmental
Dec 25, 2014
8
IR
Is blast load dependent on period of building type structur?
 
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Blast load is dependant on more factors than any other loading that I am aware of... It is also highly non-trivial.

SO: Yes, and no. The local and global effects are different than in seismic. It is very rare for an entire structure to be involved in a responce to an overpressure loading, and practically impossible for a whole structure to be involved in Brissance (with the sole, ultra-rare, effectively never considered Nuclear direct strike).

Your design is dependant far more upon where you are in the load spectrum, and load-target interaction is dependant upon both the load and the target's physical properties. You need to be considering the whole structure's period when designing a gas house or any form of industrial bunker (ie: Office spaces within a refinery, etc). These are typically the size of a construction site trailer and are subject to slow-rise, mid-peak overpressures from gas explosions. You need to

If you cannot answer the following questions, keep reading and researching until you can OR get someone to help:

- Are you in the pseudo-static range?
- Are clearance effects a factor?
- What strength increase factors and dynamic factors apply for this type of structure?
- What minimum separation distance can be assured?
- Will any areas be subject to Brissance?
- Is confinement a factor?

Beyond this, for a whole structure (like civil defence work), you need to consider:

- Progressive collapse
- Inter-element load concentration
- Set-up/Artificial Confinement

FYI, for Civil Defence training of Structural Engineers, the ability to calculate blast loading for the first time, for a single element, comes after abour six months of full time training & supervision in a specific blast hazard design role.
 
The overall effect of the blast load on a building is a function of the period of the structure versus the positive phase load duration.
 
Simplification: The pressure wave is followed by a "suction" (negative pressure) wave. If the structure period is "just right", these two will work their magic together.
 
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