Load combinations for blast load

[shrews34]

I am looking for load combinations that incorporate blast loads on a pre-engineered blast building for foundation design purposes. Does anyone have any suggestions?

 

[Gumpmaster]

Look in the Unified Facilities Criteria on wbdg.org. 3-340-01, Design of Hardened Structures to Conventional Weapons Effects may have some load combinations or other design criteria.

 

[MiketheEngineer]

My guess is that the blast load will FAR exceed anything else and it will surely blow the snow or any other loads off the building??

 

[UcfSE]

Who is specifying you need to meet blast loads? Different agencies will have different load combinations and other requirements they require you use. DoD and the UFC may not be the same as GSA, for instance.

 

[concretemasonry]

If you are designing for blast, you must be in an industrial situation or possibly subject to "strange" possiblities.

The first building I designed was a reinforced concrete "blockhouse" housing observers, computers and instrumentation complete with blast and impact resistant (8" thick) windows. It was a proven system/configuration.

We looked at blast and pressure effects from the rocket facility and designed the building including the windows, doors, walls and roof for any possible situation. It worked perfectly for the first few situations.

A few weeks later, I got called at night because of a failure. During maintenace, a liquid hydrogen tank was vented with nitrogen, but the weather conditions permitted a bubble of hydrogen gas to stay over the area above the blockhouse. Static electricity (warm, dry air) caused an ignition that created an explosion that pushed down the roof into the equipment below. The load was more than a traditional analysis (wind, blast, etc.) for roof loading

Bottom line - If you are around unusual conditions AND materials, you should widen your scope for possibility beyond the normal. For industrial or unique situations the downtime cost is many, many times greater than a little extra effort and material. This may not apply to your situation, but it was definitely a learning experience.

Dick