How to trasform blast load to static load
How to trasform blast load to static load
(OP)
we are design a curtain wall (metal studs). the blast loads have been provided as 2.5 psi/24psi-msec.
I never designed with a blast load. I think there may be a way to use an equivalent static uniform load to design the curtain wall.
Anybody knows how to trasform the loads? Thanks.
I never designed with a blast load. I think there may be a way to use an equivalent static uniform load to design the curtain wall.
Anybody knows how to trasform the loads? Thanks.






RE: How to trasform blast load to static load
RE: How to trasform blast load to static load
2nd, can you explain your blast load units ??
3rd, what if you built into the wall a flapper vent that would open if a high enough pressure was applied (relieving the wall) ???
RE: How to trasform blast load to static load
Dik
RE: How to trasform blast load to static load
Vandede, not true. I've seen videos of CFS studs working just fine in a blast scenario. They may need to be a heavy gauge and/or built-up members, but you can get them to work. Curtain walls too.
RE: How to trasform blast load to static load
ASTM Standard F2248-03, Standard Practice for Specifying an Equivalent 3-Second Duration Design Loading for Blast Resistant Glazing Fabricated with Laminated Glass.
Does any body use this method to calculate the equivalent static load?
RE: How to trasform blast load to static load
My understanding is that the F2248-03 which is titled "Specifying an Equivalent 3-Second duration design loading for blast resistant Glazing Fabricated with Laminated Glass" is just for glazig so I'm not sure you can use it for a curtain walls. I think your best bet is to obtain a copy of a program called SBEDS that you can use to determine the loads on light gage walls among other systems. You can also determine all other parameters such as ductility and rotation of the wall which determine the adequacy of the wall. This software is restircted so you or your company has to register with the Protective Design Center in order to obtain it.
Another resource I would use is the UFC 3-340-02 which as I recall has a method of figuring out the equivalent static pressure.
Good luck.
RE: How to trasform blast load to static load
Basically, you end up with a 2D frame with a dynamic, quick-acting pressure out of plane. Does anyone know of software capable of designing this? (doesn't have to be blast-specific, necessarily)
RE: How to trasform blast load to static load
RE: How to trasform blast load to static load
RE: How to trasform blast load to static load
RE: How to trasform blast load to static load
The latter is more conservative in my opinion and I would tend not to use it.
I hope this helps.
RE: How to trasform blast load to static load
My company does a lot of military design. We started out using the static procedure, but I've determined that it is too conservative with the 8x multiplier you need to use. Running the static calculations lead to using HSS tubes around each window, which in reality are not needed. So I've graduated to using SBEDS and "faking it". I want to take the next step and perform a window frame support analysis using actual dimensions and blast loads. Surely there is some software out there that can accomplish this!
RE: How to trasform blast load to static load
That wouldn't be somewhere I'd want to go for just a window.
The hardest parts of getting light gage framing to work around a window are the connections and getting the concentrated load from the header and sill to not fail your jambs. For the connection, a typical light gage connection plate doesn't really cut it. One testing project I saw shows that a bolted connection with actual steel plate (not just sheet metal) was needed to develop the plasticity and forces required required at the ends of the members. Getting the jambs to not cripple requires hefty stiffeners.
We've bitten the bullet and just use HSS surrounds around all windows. It opens up a lot of flexibility and our window sizes aren't as limited as they would be using cold formed window surrounds.
RE: How to trasform blast load to static load
You may find good information in the TM5-1300 code for Blast loads.
or you can use SAP2000 program, I am not sure if it's capable of analysing a 2D opjects subjected to blast loads , But I used it to analys steel beams and frames for dynamic blast loads, and it gave reasonable results.