Steel Joist Uplift Calcs 6

[mtkauff]

I am a project manager for a commercial gc in tampa. The SE on my project says he needs the uplift calcs on the open web steel joists before he will approve the shop drawings. Our fabricator (Nucor) is stating that the calcs cannot be determined until the joists are fabricated. This is a cath 22. Who is right? Any insight would be appreciated.

 

[JedClampett]

The Engineer of Record (the design engineer; your SE)should determine the uplift forces, including uplift and record them in the contract documents, either drawings or specifications. The joist manufacturer uses these forces combined with the joist span and spacing to design their joists.
If the forces are provided, I don't understand Nucor's response. They are responsible for fabricating the joists. They should know what their properties are and can use these properties in designing them.

 

[Ron]

JedClampett is right on target. This shouldn't be an issue. Nucor should be able to provide them. If they know where the project is located and the dimensions of the building (which they do of course), they can provide uplift calcs. using their joist properties.

Under Florida law this is a delegated function, specifically covered by the rules of the Board of Professional Engineers. They (Nucor) are obligated to provide the SEoR with adequate information (at his determination) to review and approve the shop drawings.

 

[Lutfi]

mtkauff,

I live in Florida and have been practicing structural engineering her since the mid 80s. The SEOR of record is responsible for the entire structural integrity of any structure he designs. He may delegate the design of parts and portions of the structure according to Florida Administrative code. I like to point you to part 61G15-31.006 “Design of Structural Systems Utilizing Open Web Steel Joists and Joist Girders of the rules. These rules can be found at this link:

http://www.fbpe.org/pdfs/chapter61g15August2004.pdf

Rule 61G15-31.006 specifically states "The Engineer of Record may require the submission of the steel joist and joist girder design calculations as an indication of compliance. When required to submit the steel joist and joist girder calculations, the steel joist and joist girder manufacturer shall submit a cover letter along with the steel joist and joist girder design calculations. The cover letter shall bear the seal and signature of a Florida registered professional engineer responsible for design of the steel joist and joist girders.”

What I usually do is require the shop drawings and the calculations to be submitted at same time. Then I can review the calculations and the shop drawings at same time. I normally specify the joist size and any special loading on the joists on my design plans. I indicate the minimum bridging and I require that the joist receive uplift bridging on the bottom chords per SJI specifications.

I am very familiar with Vulcarft (NUCOR) and they are intimately familiar with these requirements. I must say I never had a problem with them furnishing the calculations nor the shop drawings before fabrication I may add. If hey fabricate before approval they are taking a huge risk. I see shop drawing approval process not only as compliance but dimensional check by the contractor and also an engineer’s last resort to catch any “errors” before fabrication.

I indicate on my plans either the net uplift pressure or I indicate the gross uplift pressure on zones 1, 2 and 3 of the roof (this is FBC and ASCE 7 terminology). If I provide gross uplift pressure I do provide the dead load and let the joist engineer determine the net uplift.

I think you are misquoting the joist manufacture. They are not supposed to fabricate the joists until the shop drawings and calculations have been reviewed. They also cannot fabricate the joists till they run the calculations first. Therefore, I see no catch 22 situation. You may want to talk with the engineer and the joist suppliers in a conference call to clear any confusion. YOU MUST SUPPLY THE CALCULATIONS TO THE EOR.

Good luck.

 

[Lutfi]

Let me add that Ron and Jedclampett are both correct.

Happy Turkey Day to all

 

[Ron]

Lutfi...Happy Thanksgiving to you and all. Looks like a rainy one for Central Florida.

 

[mtkauff]

Thanks Jed, Ron and Lufti. This clarification is a big help. I am starting to wonder if our steel contractor was not communicating correctly with his supplier (Nocor). We did get the shop drawing rather quickly from Nucor, but the calcs were not included. The submittal went back and forth and created a 4 month delay to the project due to answers finally being resolved long into the steel market problems of earlier this year. Our sub is claiming damages because he was pointing his finger at the engineer, but I think he may have dropped the ball, especially if Nucor (and any registered FL structural eng) knows that the uplift calcs are to be supplied with the shop drawings.

I truly appreciate your expertise in this subject.

 

[JStephen]

If the calcs can't be determined until the joists are fabricated, then how do they know how to fabricate the joists? Obviously, something is off there.

Two related issues that DO sometimes crop up- can't get material test records until material is delivered (to the fabricator)- or can't get welder certifications until welders are assigned. But calcs should be no problem.

 

[Lutfi]

Ron,

I am heading to the mountains of West Virginia. I can smell the wood and coal buring fire places. Country Roads, take me home... to the place I belong...

I think everyone knows the rest.

Bye to all for now.

 

[structuresguy]

The only time we have had problems getting signed and sealed calcs from the joist fabricators is on a job where our specs inadvertently were worded in such a way to require both the shop drawings and the calcs to be signed and sealed. Once this typographical error was brought to our attention, we clarified only the calcs needed to be S&S.

Also, we always show a gross uplift diagram on our drawings showing the various specialty trades (joists, deck, roofing, etc) exactly what gross uplift loads they should use for their calculations. However, if we did not have this, they would still be able to calculate it for themselves as in FLorida you are required by teh FBC to clearly state the wind design parameters on the structural drawings. This way, any specialty engineer, from anywhere, can correctly calculate the wind pressures for the particular building/site conditions.

I think Lutfi is right on. There is definitely some break down in the communication process here that a conference call would clear up right away, I am sure.