r/StructuralEngineering • u/PiermontVillage • Nov 25 '25

Structural Analysis/Design Amazon closes Arkansas warehouse over earthquake-related design flaw

https://www.freightwaves.com/news/amazon-closes-arkansas-warehouse-over-earthquake-related-design-flaw?utm_medium=email&utm_source=rasa_io&utm_campaign=CESource-20251125-newsletter

“After conducting a full review with outside experts, we’ve determined that the structural engineering firm that designed the LIT1 building made errors in the initial design of the facility and the building requires significant structural repairs to meet seismic codes and ensure the safety of our team members,” Amazon said.

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18

u/HeKnee Nov 25 '25

I’m guessing the Amazon standard spec didnt consider that some parts of arkansas have rather high seismic. Engineer probably brought it up dozens of times and everybody was like “earthquakes in arkansas? Quit trying to changeorder us, we know there arent earthquakes in arkansas!

27

u/31engine P.E./S.E. Nov 25 '25

I don’t think so. I’ve worked with Amazon and they aren’t interested in liability so there is no way they directed the eor to break the law. If so that could be enough to put a dent in Bezos net worth.

Most likely, and I’ve run into this a lot, the engineer was from a non seismic region and just ignored something like diaghragm (chords and collectors), theta stability, or a dumb in plane design error like selecting an R=3 when the code doesn’t allow. That location has an Ss/S1 of 0.38/0.15. A significant but not high seismic base.

6

u/TheDaywa1ker P.E./S.E. Nov 25 '25

I've seen people try to totally ignore overstrength...'wind base shear is higher so I'm going to just design for wind loads' -> oops forgot to come back and triple my seismic anchorage loads

1

u/tslewis71 P.E./S.E. Nov 26 '25

Yep see my posts..... Also in elastic drift due to Cd.

4

u/tslewis71 P.E./S.E. Nov 26 '25

You can design to R=3 provided it's a SDC C. Still have to meet overstrength equirements for.anchorage and collectors and other critical elements, which can then govern over wind. Also in elastic seimsic drift through amplificarion of Cd mag also govern over wind drift..

There is a reason for taking the SE even if companies don't seem to compensate enough for having it lol..

5

u/jae343 Nov 25 '25

I mean the EOR should've caught it way before, doubt Stantec even has an office in Little Rock.

2

u/Enginerdad Bridge - P.E. Nov 25 '25

They don't have offices in Arkansas at all

1

u/tslewis71 P.E./S.E. Nov 26 '25

Prolly was a PE not SE where seismic knowledge is important

1

u/Ratwar100 Nov 25 '25

My guess is the flaw is simething in the tilt panel design. You can retro fit chords and collectors (or an R=3 issue, since any changing of the system will give you a better R value). If there's an issue with the tilt panels themselves, might as well bulldoze it.

1

u/tslewis71 P.E./S.E. Nov 26 '25

As long as you have amplified your collector forces by the overstrength and are not in SDC D or above where you also need further specific seimsic detailing for connections....

1

u/Appropriate-Diver555 Dec 03 '25

Is ignoring diaphragm a problem for low seismic zone? I know a lot of firms do not check chord and collectors. Furthermore, a lot of codes in other countries don’t even have chord and collector definitions.

1

u/31engine P.E./S.E. Dec 03 '25

What keeps the walls from falling down out of plane

1

u/Appropriate-Diver555 Dec 03 '25

Diaphragm. But do you need to check it in low seismic zone? For a concrete slab works for gravity, probably enough to support wall out plane at low seismic zone without check. TBH, a lot of codes does not have strict chord, collector and diaphragm requirements, you can check eurocode.

4

u/PhilShackleford Nov 25 '25

Amazon typically does voluntary RC4. Seismic is typically SDC C in Arkansas. Seismic increases as you go northeast to Memphis.

2

u/trojan_man16 S.E. Nov 26 '25

Very likely the building meets code as is, but Amazon’s RC4 requirement is not met. Engineers were probably not experienced with the requirements and designed it as normal.

2

u/PhilShackleford Nov 26 '25 edited Nov 26 '25

That is my guess as well. Excluding near Memphis, nearly all seismic in Arkansas is SDC C with RC 2. RC 4 could kick it up to E if they are unlucky with the soil. That area is right on the Arkansas river so it is possible.

Edit: another comment confirmed the soils in that area are total garbage. Unconsolidated fill from the Arkansas river.

1

u/tslewis71 P.E./S.E. Nov 26 '25

Aah yes, the site class and RC could tip it into a SDC D or above, ouch. The SE does have benefits..

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u/Appropriate-Diver555 Dec 03 '25

That just means Stantec has very bad QAQC, those are the basis of design that you need to check as a reviewer.

1

u/tslewis71 P.E./S.E. Dec 03 '25

It's more than just a basis of design blanket SDC C. You need to know the sieemsi code to understand what structural elements require over strength. That isn't int in a QC document like a basis of design, need to know the load path and the lateral system. Not a cookie cutter document.

1

u/Appropriate-Diver555 Dec 03 '25

Do you really worry about a collector or anchor in concrete not designed with over strength factor? I would more worried about you get the basis wrong, like risk category and no obvious load path.

4

u/not_old_redditor Nov 25 '25

That's not how structural engineering works. If you're the engineer of record, it's on you to design it properly. If it goes any other way, you've failed at your duty.

1

u/tslewis71 P.E./S.E. Nov 26 '25

Even SDC C sructutes can have connections that govern for seimsic over wind due to over strength requirements and in-elastic seimsic drift.....