huangyhg

design loads - explosions
i designing a locker room utilizing masonry walls, and within the building is a mechanical room. the design criteria states the separator wall between the locker room and the mechanical room shall be "explosion-proof". what design pressure is sufficient for such a load case? i don't recall any such discussion in boca.

zulak
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no idea but i think that the max pressure for which the tank would explode multiplied by the gaseous volume of the tank at explosion time and divided by the volume of the room should give of necessity a superior limit to this.
these references are probably overkill, as they are more suited to protective design in a military or industrial environment.
the two main references are:
army technical manual tm 5-855-1 fundamentals of protective design for conventional weapons
and
army technical manual tm5-1300, structures to resist the effects of accidental explosions
i'm not sure if the 1st reference is available to the general public, but the 2nd reference definitely is.
yet even knowing this data and to the usual rates of pressure for boilers this could give awesome pressures. in the same manner that the risk of explosion of the boiler itself is prevented by a limit pressure valve, you must protect equally the room that contains it by one conduct of ample section to the exterior, maybe weakly closed (to not stand significant inner pressure). this way you will alleviate the augment of pressure to rational levels.
the typical minimum over-pressure required by factory mutual insurance is 100psf for this type of application.

a cautionary note on ishvaag's first post--i understand the line of reasoning, and believe that this would likely result in an non-conservative answer. this essentially would come from the ideal gas law, and in no way is taking into account dynamic effects resulting from the explosion (which would likely result in much higher pressures).
bradh, i need to agree with you, was exactly what you said, and so i here say.
a shockwave overpressure effect must be present i agree.
on the other hand, only the assumption of the existence of enforced holes may be making the 100 psf of other post safe enough.
in any case this kind of things must be by now very well studied, i think, and so i would try to comply with some code saying something about.
thanks, bradh
i am also interested in such design. because i am working on evaluation and upgradation of the control room of a petrochemical plant. for me the design pressure is nearly 285 psf and an impulse load of 86,000 psf-sec. can anyone help me?
msajjadh - see my post above. these are the manuals that many corporate standards in the chemical industry reference.
thanks butelja - but these manuals are not available. i have only asce task committee report "design of blast resistant buildings in petrochemical facilities". in this report they are following single degree of freedom (sof)system. there is an example given in this report. every component of the structure is considered saperately. its time period is calculated. and the interesting point is, that for every component (beam, column of slab) time period is diffrent. now the problem is, what should the period of the structure, and how it will respond to the explosion load.
i hope you will respond asap. thanks a lot.
in my opinion, the room should be designed to insurance requirement of 100 psf and a blow out panel to release inside pressure above 100 psf.

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