Blast Analysis

[engpes]

I am a licensed mechanical engineer that does quite of bit of structural design and analysis with modular buildings.

I have had several non-linear blast loading applications in the past that I have avoided due to my inexperience with this subject.

I have recently done quite a bit of research on this subject and have thoroughly read the ASCE Guide for the design of blast resistent buildings in petrochemical facilities. I feel that I understand the design concepts and after much more research could reach a point where I can perform this analysis.

My question is this:

1.) As a mechanical engineer, do I have any business dealing with building blast analysis? (after much diligent research)

Thanks in advance.

 

[bridgebuster]

As Dirty Harry said, "are you feeling lucky today?"

On a serious note, if there are no legal restrictions where you practice, i.e. your state licensing board doesn't define who can do what, and you believe yourself to be competent it's up to you.


I was involved in a tunnel project that had to be designed for blast. Some of the people doing the analysis were physicists.

 

[IRstuff]

Ostensibly, not in California. You ought to be a licensed civil engineer

Civil engineering embraces the following studies or activities in connection with fixed works for irrigation, drainage, waterpower, water supply, flood control, inland waterways, harbors, municipal improvements, railroads, highways, tunnels, airports and airways, purification of water, sewerage, refuse disposal, foundations, grading, framed and homogeneous structures, buildings, or bridges:
(a) The economics of, the use and design of, materials of construction and the determination of their physical qualities.
(b) The supervision of the construction of engineering structures.
(c) The investigation of the laws, phenomena and forces of nature.
(d) Appraisals or valuations.
(e) The preparation or submission of designs, plans and specifications and engineering reports.

Mechanical engineering is that branch of professional engineering described in Section 6734.2 that deals with engineering problems relating to generation, transmission, and utilization of energy in the thermal or mechanical form and also with engineering problems relating to the production of tools, machinery, and their products, and to heating, ventilation, refrigeration, and plumbing. It is concerned with the research, design, production, operational, organizational, and economic aspects of the above.

One might argue that explosives are a form of thermal energy, and therefore falls under the purview of an ME...

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[a2mfk]

It sounds like you are going about it the right way as far as educating yourself. But as a structural PE who has zero experience in blast analysis, my first project or two I'd want a SE mentor along for the ride...

I would think with some of your dynamics and stress analysis background you'd be suited for this type of work, especially in determining loading and pressures. But when it comes to design of the actual structure you may need some guidance.

 

[MiketheEngineer]

I believe most states say something along the lines of "if by training or experience".... you can do what you are comfortable with.

A few states dictate a SE license for certain structural work.

You might want to check w/ your insurance carrier, also.

I have done some things out of my area - but always had an expert to back me up until I felt comfortable.

 

[delagina]

i've seen mechanical engineers do furnace structures and just use staad. they dont input unbraced length, K values for columns, etc..

sometimes the problem is some engineers think they know what they are doing but they dont. that's me included sometimes. ahahaha

 

[TXStructural]

You have no business doing building structural analysis as an ME. That is to say that being an ME does not qualify you. Which begs the question: Are you the HVAC kind of ME, or the kind that was trained in structural analysis for equipment and structure design? Just as with civil engineers, there are different flavors of mechanical engineers.

But, if you have developed other competencies from additional education and experience, and you are able to discern good analysis results from bad analysis results by various methods, then there should be no problem.

In Texas, the rule is that you need to demonstrate competency in a field through 1) a degree, 2) sufficient experience of increasing responsibility, or 3) NCEES examination in the discipline.

I'd suggest finding a mentor in the subject and working with him or her to establish your competency as you work on this project. Look at local universities or government facilities (like the Corps of Engineers).

 

[dik]

It's undertaking new 'stuff' that brought us out of the caves!

Dik

 

[engpes]

Thank you very much TX Structural and everyone else.

The majority of my experience comes from mechanical equipment structural design (basket lifts, component stress analysis, piping, skids, etc.).

To be clear, this is a single steel portable modular living quarter....not a multistory complex structure.

Would the Corps of Engineers have some sort of training/consulting program for this?

Thanks a lot!!!

 

[TXStructural]

It sounds like you are working in your expertise, but probably need to be really diligent about working up your models, since blast mechanics is a really specialized field.

I had occasion to FEA model some blast situations, and it became apparent that tools like Algor break down when the model is not sufficiently detailed, and modeling certain materials is just very difficult when it comes to blast effects. You might contact the INEL (Idaho National Engineering Laboratories) to see if they have public documents which you can examine. The COE facility in Vicksburg, MS has done some blast work, and we were doing some at Stennis Space Center under US Army AMCCOM in the 80's.

Also, consult with the relevant COE/UFC documents:

http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

for more guidance.

In areas sufficiently near the origin of the blast, consider that most materials act brittle ("brisance") and traditional mechanics of materials may not apply very well. I am not the best person to help with blast and fracture mechanics, so maybe someone who is can chime in.

You might also dig around the FEA section of this website for some guidance on blast modeling.