Design of blast doors

[knandwana]

Hi All :

I am currently working on a project where I have to design a blast door. I have used TM5-1300 Manual for design of monolithic steel door. The issue is if I use a 1" plate thickness I do not meet the customer requirements(high ductility ratio and rotation ). But if i use a 2"
plate , I do meet the requirements but the door weight becomes high and is not acceptable to the customer. So what we need to do is use a 1" plate and place stiffeners at critical locations, but I don't know how to analyze the blast doors with stiffeners on them , since TM5-1300 does not talk about those kind of doors.

Can you all learned people suggest me as to how should I approach this problem ?

Thanks,
Kapil
Structural Engineer, EWI

 

[ishvaaag]

One thing is that the referred code simply won't allow the stiffeners's solution, that's checkmate, and other simply how to calculate for some forces the plate with stiffeners. I unfortunately am not expert to help in matters related to blast, but to design some stiffeners for some equivalent strength to some represented by a plate of given thickness one can find simply the equivalence to stand the forces and that's all. If, however, there are local shear requirements of say fusion that requires the 2 inches plate we have again checkmate.

 

[msquared48]

Does the door have to be flat? Can it be rounded or curved to deflect some of the force, allowing it to be thinner - like an arch effect?

Mike McCann
MMC Engineering

 

[steellion]

Is TM5-1300 an acceptable alternative to the UFC for your project? To me, I think it is outdated and UFC use is requirement for government construction. If it is commercial construction and you need the blast door for a chemical lab for example, then TM5 should still be okay.

 

[boo1]

Consider using Unified Facilities Criteria (UFC) 3-340-02 replaced TM 5-1300 in 2008 (

http://www.wbdg.org/ccb/DOD/UFC/ufc_3_340_02_pdf.pdf

)

Design of a build up steel blast door.
Methodogy Section 5-36.6.2
Example in Chapter 15 and 5A-7.

 

[knandwana]

I had checked this reference, but it seems like this example is valid for low pressures, however for my case the Pressure is 333 psi for 0.68 milliseconds.

What approach should I take for this case ?

Thanks
Kapil

 

[ishvaaag]

if the only requirement is some uniform pressure that you know it is efficiently held by the 2" or some lesser uniform plate thickness, you may design as is your intent an stiffened plate of even lesser thickness able to support the same uniform pressure than such plate is able to resist. Identify from the valid thickness (both testing shear and moment) what the equivalent loads must at least be -for any significant span, moment at the center should control the actual load being sustained-, and then apply such load to some tentative stiffened plate; this you can make in some FEM package such RISA 3D or SAP 2000 and many others. Find such way a satisfactory stiffened plate. This should work well except that some other mandatory specifications wouldn't allow lesser thickness than the 2" you are finding.