Modifying interior X bracing to accomodate doorways 1

[ErichGunther]

I have partial ownership in a three story office buildiing that is 12,000 sq. ft per floor. On each floor there are three sets of box beam type X bracing to add structural rigidty and manage wind loading. The owners/tenants of the second and first floor are doing a rennovation and want to alter the X bracing in the middle of the building to allow for doorways on the first and second floors. The proposal that came back is illustrated in the attached drawing. Basically the proposal is to remove one of the lower legs of the X on the first and second floors which makes room for the new doorways. I am an electrical engineer with only enough structural engineering background in school to be dangerous but it sure does seem to me that this change eliminates much of the capacity of the X bracing as originally designed. I am wondering if anyone on this forum can tell me what questions I should ask the engineer on this job (once I determine that there is an engineer on this job) about the impact of this change. Has anyone seen this done before in other buildings? Is the proposed change totally nuts on its face, or not uncommon as long as revised loading calculations are done?

Erich - erich<at>enernex.com

 

[paddingtongreen]

Having retrofit industrial and power plants, I've had to do this sort of thing many times. If I put my seal on it, or if my boss put his seal on it, it was good, we had taken care of business. I would not mind explaining the rationale to an owner, or to a peer review, but anything verging on an accusation of bad design would shut me up like a clam and have me putting my deductible into escrow and alerting my insurance company.

Frankly speaking, Erich, you were lucky they hired an engineer for the work. A lot of companies just call in a small contractor to chop the hole and put in the doorway.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[ToadJones]

Pad-
Right one man, power plants are full of these types of retrofits.
Is it IPA time yet? ...ahh....only 10 o'cock.

 

[ErichGunther]

Thanks to everyone for the amazing response to my query and the very informative posts! I now have what I need to ask good questions of the builder and engineering firm. I will post an update on the outcome.

BTW, I like the suggestion about IPA time. If you want to engineer your own IPA, see my article on that topic at

http://bit.ly/d5KAP4

 

[ToadJones]

Erich-
Whats your favorite store bought?
I have found Sierra Nevada's Torpedo to be excellent.
Sam's Latitude 48 is also quite good.

 

[ToadJones]

The single greatest beer of all time however, might be Troeg's (of Harrisburg, PA) Nugget Nectar.

 

[csd72]

Lagunitas censored ale from just north of San Francisco.

Not for the faint hearted.

They also do an IPA.