×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Reinforced Masonry CMU wall with SBEDS

Reinforced Masonry CMU wall with SBEDS

Reinforced Masonry CMU wall with SBEDS

(OP)
I have to designed an enclosed control room (15') to withstand a 3psi load with a duration of 40ms. After entering my inputs for a masonry wall with #5 bar in every cell filled with grout the program tells me it works (incident angle < 2 degrees). My gut tells me this is inadequate. Anyone else have these results?

RE: Reinforced Masonry CMU wall with SBEDS

Not really enough information provided to tell one way or the other. Have no clue if you're using 6" block, 8" block, 12" block. Don't know boundary conditions. Don't know what, if any, axial loads there are to contend with. May very well be fine, that's a lot of reinforcing and a relatively small 15' span.

Not sure I understand your loading criteria though. Are you saying a constant 3 psi for 40 ms and then drops to zero? I'm not familiar with any standard blast loadings that take this form, should be a peak pressure that dies out quickly and then goes into a negative rebound phase. If that 3 psi is your peak pressure and then dies off over 40 ms then what you have would very likely be overkill. 3 psi is pretty small peak pressure as far as blast is concerned.

RE: Reinforced Masonry CMU wall with SBEDS

Are you sure you have the units right? Most CMU programs are written for psf, not psi. Big difference.

RE: Reinforced Masonry CMU wall with SBEDS

I have used SBEDS for metal stud walls. So you have 432 PSF for 40 ms. Maybe there is enough mass in the wall to absorb that. I recall that was the case with metal studs as the heavier the wall got (adding veneer etc.), the lower the peak loads.

RE: Reinforced Masonry CMU wall with SBEDS

Jed- OP is talking explosion/blast loads, SBEDS is a blast program/spreadsheet developed by the US Army Corps of Engineers. Psi is actually correct, 3 psi is reasonable for an average if you're just dividing your impulse by time, pretty low if that's your peak pressure. We routinely see peak pressures much larger than that, but it drops off quickly.

RE: Reinforced Masonry CMU wall with SBEDS

Why do you feel that <2 degrees is inadequate?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources