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School Used as Emergency Shelter - Any Design Changes?

School Used as Emergency Shelter - Any Design Changes?

School Used as Emergency Shelter - Any Design Changes?

(OP)
I recently completed the structural design of my old grade school.

The school has came back and said they want to use the new school as an emergency shelter in the event an emergency comes up.

Are there any changes structurally I would need to do to my design?

To me, it would seem it is just back-up power (redundancy), lighting, food and water storage that need to be considered and nothing structural.

Thank you,

D

RE: School Used as Emergency Shelter - Any Design Changes?

Have a look at ASCE 7 section 1 regarding importance factors.

RE: School Used as Emergency Shelter - Any Design Changes?

Assuming your project is subject to ASCE 7, the occupancy category might change to IV.  This includes "designated earthquake, hurricane, or other emergency shelters."  Does the owner's intention fit this description?

RE: School Used as Emergency Shelter - Any Design Changes?

(OP)
Thanks for the help.  It changes the lateral loads substantially with the change from category III to IV after reviewing the ASCE-7.

RE: School Used as Emergency Shelter - Any Design Changes?

And I might add a bit of a cushion....

RE: School Used as Emergency Shelter - Any Design Changes?

flood height?

RE: School Used as Emergency Shelter - Any Design Changes?

Not sure where you're located, but in my area (Florida), when we are considering emergency shelter applications, we typically take the wind design for coastal areas to a Category 5 storm rather than the typical code application (Cat 2,3, or 4 in most areas).

If you have seismic considerations, you might increase your seismic loading similarly.

RE: School Used as Emergency Shelter - Any Design Changes?

(OP)
It's in North East Oregon.  We're pushing for them to not go this route as the design is already done and the contractor has already made his bid.  This change would have a pretty substantial affect on the cost of the school.

RE: School Used as Emergency Shelter - Any Design Changes?

We recently worked on a school, which designated only the gymnasium as a tornado shelter.  The design significantly changed the structure.   

http://www.FerrellEngineering.com

RE: School Used as Emergency Shelter - Any Design Changes?

Gymnasium as a tornado shelter, I really hope you advised them against this.

This is a loaded question because the owner's expectations of a shelter are usually very different than what can be provided.   

RE: School Used as Emergency Shelter - Any Design Changes?

We've done numerous elementary school gyms as shelters - can be done - just need to deal with the loads, indirect gym entries, etc.
 

RE: School Used as Emergency Shelter - Any Design Changes?

Really?  Arent the pressures for a true tornado shelter enormous in FEMA 361?  Would think it'd be nearly impossible to meet for large spans/walls.  

RE: School Used as Emergency Shelter - Any Design Changes?

Emergency shelter suggestions for groups have been developed by FEMA (fema.gov, I believe).

They do not address the structural systems of a gym or other vulnerable structures. The concept is life safety/survival under severe conditions. Obviously a tall floor space would be bad choice, but the lower areas with more stability and less exposure make more sense.

Most of the suggestions (not a code) are based on life safety and protection from winds and especially projectiles, because FEMA has a great background in that area. For residential protection from projectiles and debris (the largest cause of deaths), there only a very few select wall systems recommended because of the extensive testing over the last 15-20 years or so. These can be used or existing walls can be modified to approximate the results, but not quantified.

It is well worth the time to look over the concepts and see how they apply.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

RE: School Used as Emergency Shelter - Any Design Changes?

For a school/shelter in a hurricane-threat area (not Oregon ?) wouldn't the windows have to be addresses against flying debris?

Than again, my old grade school was built pre-air conditioning and pre-Columbine (warfare) problems, so maybe new schools have "no" outside windows .....

RE: School Used as Emergency Shelter - Any Design Changes?

dhoward26...
Has the contract been awarded? You mentioned you had bids. Change is significant that re-tender might be in order.

I would suggest that you do not 'push for them not to go this route'... in the event that there is a problem and collapse, you may be in for serious law suits.

If the school wants this, then deal with it as a significant change.

Dik

RE: School Used as Emergency Shelter - Any Design Changes?

MainMan10 - this was a no-window smaller elementary school gym - 12" fully grouted CMU with rebar in every cell.  Heavy roof system tied down to the walls with extended anchorage (about 3 to 4 feet down the wall).  It was based on 200 mph now that I think about it.  Yes the loads were large but not to the extent we couldn't design for them.

FEMA 361 does address the structural design of buildings used as community shelters.  It deals with both loads and projectiles.  ICC 500 is the newer "code" version of the FEMA guidelines.

 

RE: School Used as Emergency Shelter - Any Design Changes?

Watch the detailing and construction of the roof-to-wall connections, and the roof attachment to the purlins.  A gym is a poor choice with the best installed work.

There is a *very valid* reason that hallways and bathrooms are the traditional areas of choice for 'hardening'.  Your customer is trying to "reinvent the wheel".  Sometimes [almost always] the 'usual & customary solution' represents an optimal design.

Wheels are round for a reason.

RE: School Used as Emergency Shelter - Any Design Changes?

I agree w/Duwe6 - small halls and baths are naturally "hardened"  Just beef them up a bit and designate them as the "emergency" area.

Done all the time.

RE: School Used as Emergency Shelter - Any Design Changes?

We typically design emergency shelter in accordance to FEMA 361.  All windows/doors should comply to FEMA 361 for missile impact resistant.  Otherwise, pending on the opening, the roof may have to be designed for partially open C&C wind, which is much larger.

Also - Check with the owner to determine the tornado category, typically in fujita scale, F1, F2, etc.  go to national weather website to find the corresponding 3-sec guest wind speed.

RE: School Used as Emergency Shelter - Any Design Changes?

The projectile criteria is a major influence on the selection of walls. It is NOT a structural criteria, but is based on actual standard penetration tests (12' long 2x4 fired from an air cannon at about 145 mph) conducted through the years at a university in Texas. The acceptable walls must meet the criteria of NO penetration. 8" reinforced (8" o.c.) concrete and and reinforced masonry were the only acceptable wall sections for many years and finally a wood wall section got approval, but it is 8" studs at 12" o.c. and sandwiched by 3/4" plywood plus steel plate.Of course, the roof must also meet the requirements.

Keep in mind this is really for tornadoes and not hurricanes that typically have much lower winds. The concept is meant to be applied to small life saving structures for survival and not for groups with longer term needs.

Windows obviously have a more relaxed threshold, because shutters or other systems are also expected to be used or required.

Dick

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

RE: School Used as Emergency Shelter - Any Design Changes?

dhoward - sorry that your thread has been deviated from your original questions - for all you gym-shelter bashers - I've done many per FEMA 361 and it can be done- does make sense (if you look at the areas required per person the hallways, etc don't provide enough and you struggle to avoid projectile defense due to too many open areas and doors).

The anti-gym bias is typical with a lot of folks because for many years schools were instructed to stay away from large gym rooms because of their tendency to collapse in high winds.  People were instructed to sit in the long hallways with their head between their legs - with light gage metal deck roofs above and glass windows and doorways at either end...

I designed a school gym in the 1990's under FEMA 361 for 200 mph.  The school was actually a new one my two kids were eventually to attend.  After it opened I visited with the principal and asked if he was all clear on the use of the gym for storm shelters.  He blinked at me and said, "No, no.  The Civil Defense inspector slapped a shelter sticker on the mechanical room - that's where we should go."  I had to do a lot of communicating with the school district to straighten that out as the mechanical room was only framed with light steel beams, hollow core floor above (for the air handlers) and was perhaps the worst place in the world to go.  They finally instructed the principal to head to the VERY hardened gym structure...much to my relief.

Texas Tech (Mehta et al.) have provided testing for projectiles and in some cases 4 1/2" concrete walls are enough.  FEMA 361 suggests 6" thick.  I've worked with Texas Tech on projects in the past and we've been in situations where a 4 1/2" concrete wall panel was acceptable.  The missle test is 100 mph (not 145) and a 15 lb. 2x4.

dhoward - you use the term "emergency shelter" which doesn't necessarily mean tornado or hurricane.  You might clarify.

 

RE: School Used as Emergency Shelter - Any Design Changes?

Agree with dik....if you push cost over safety, you will lose the liability game.

JAE is exactly right.

RE: School Used as Emergency Shelter - Any Design Changes?

One other aspect of emergency shelter design is that the mechanical & electrical systems must continue to function without interruption. Roof-top equipment and equipment mounted outside on the ground must be protected from flying debris. Protection usually involves enclosing the equipment with with a steel cage, clad with heavy wire mesh or expanded metal. The enclosure has to resist a missile impact.

Count me as a vote for JAE regarding gym shelters. I have designed three schools in Florida with such a requirement. It's been awhile so I can't recall the State document we were required to follow for the design, but roof uplift loads in the corners of the building can be on the order of 200 psf or more. The walls are either tilt-up concrete or solid-filled & reinforced masonry.

RE: School Used as Emergency Shelter - Any Design Changes?

Sorry guys - last place I am heading to is the gym.  I have NEVER seen one that would come even close to surviving a tornado.

If you have designed such a beast - KUDOS - and I believe it could be done - just the ones I have seen would be worthless.

RE: School Used as Emergency Shelter - Any Design Changes?

(OP)
Good conversation here.  Update on this: The school has decided to shy away from using this as an emergency shelter.  I'm not sure what all was involved with the decision for it as the Architect spear-headed it.  It would have been an interesting to go back through and see how the design would have changed.

Thank you for the ideas and suggestions.

RE: School Used as Emergency Shelter - Any Design Changes?

Most of the change = $$$$$

JAE got it right; it's readily 'doable' with a big budget.  Heck, the Army made an above-ground bunker that withstood being inside an atomic fireball.  $$$$$$

RE: School Used as Emergency Shelter - Any Design Changes?

Sure - if you have enough time and money we can move the St. Louis Arch or the Washington Monument!!

RE: School Used as Emergency Shelter - Any Design Changes?

dhoward... just make sure their reason wasn't based on your 'pushing...' and that it's clearly documented as such...

Dik

RE: School Used as Emergency Shelter - Any Design Changes?

My two cents.  Hurricane, the gym, if I know how it is built and tied together.  Tornado, a basement somewhere.

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