Delegation of Wind Load Calculations?
Delegation of Wind Load Calculations?
(OP)
Greetings everyone. One of my clients is a steel fabricator. They are working on a project with open-web steel joists. I think the joist manufacturer is a sub to the fabricator. I haven't been involved in the project up to this point.
It's a small retail building in a high wind zone. The structural design information is on the architectural drawings, so the architect is apparently acting as the registered design professional for structural. The construction drawings do not include any wind load design criteria for delegated design. The joist manufacturer sent an RFI to the fabricator asking for the wind uplift pressures.
Clarification: this is only about roof uplift components and cladding, not about main wind force resisting system design.
I'm told that an RFI was sent to the architect about this, and the answer was the joist manufacturer is to calculate the uplifts. They're obviously violating the IBC Ch. 16 with this, but they probably don't know that. To get the project unstuck, my client contacted me to see if I can provide the wind uplifts for the joist design.
I have a license in the project state and can easily provide these. I could clearly state that my scope is limited to the pressures for steel joist design. I could also request that the calculations be sent for approval by the registered design professional, but I'm not sure they would be.
The fact that the IBC says this info must be on the construction docs implies that this should not be delegated. Should I contact the building official to make sure they're OK with this?
I feel like I might be missing something here.
Any advice would be appreciated!
It's a small retail building in a high wind zone. The structural design information is on the architectural drawings, so the architect is apparently acting as the registered design professional for structural. The construction drawings do not include any wind load design criteria for delegated design. The joist manufacturer sent an RFI to the fabricator asking for the wind uplift pressures.
Clarification: this is only about roof uplift components and cladding, not about main wind force resisting system design.
I'm told that an RFI was sent to the architect about this, and the answer was the joist manufacturer is to calculate the uplifts. They're obviously violating the IBC Ch. 16 with this, but they probably don't know that. To get the project unstuck, my client contacted me to see if I can provide the wind uplifts for the joist design.
I have a license in the project state and can easily provide these. I could clearly state that my scope is limited to the pressures for steel joist design. I could also request that the calculations be sent for approval by the registered design professional, but I'm not sure they would be.
The fact that the IBC says this info must be on the construction docs implies that this should not be delegated. Should I contact the building official to make sure they're OK with this?
I feel like I might be missing something here.
Any advice would be appreciated!
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RE: Delegation of Wind Load Calculations?
Can you contact the Architect, since they are the registered design professional? Or is that crossing the client/consultant line?
Gut feel is that, yeah, you can probably do the calculation from a numbers-on-paper point of view. But, ultimately it's a liability issue because who is owning the building design. In my experience, you can't (or shouldn't) really delineate the Vertical System design from the Lateral System design because they should coordinate.
I don't practice in the States, so only providing an opinion based on how it's generally presented here.
RE: Delegation of Wind Load Calculations?
A clarification: this is only for roof joist uplift design, so it's components and cladding, not main wind force resisting system
RE: Delegation of Wind Load Calculations?
The most proper mechanism I can think of would be for the Architect (EOR) to contract with you to determine C&C pressures and MWFRS pressures for the Joist MFG to design (delegated).
This brings up the dubious point that I am sure you don't want to tread into. Should the Architect really be stamping design load data if they cannot produce it themselves? Any competent engineer should be able to determine these pressures and indicate them properly. The arch have already shown their hand that they don't really understand the structural provisions (even the most basic CDs requirements) by calling for delegated design without indicating the proper wind design data.
If you don't get the Arch to indicate this properly on the design drawings, and you instead submit your calcs and your statement limiting scope, well now all you have done is become the most competent engineer on a project that is not conformant to the IBC.
RE: Delegation of Wind Load Calculations?
I think driftLimiter is mistaken - you won't be the most competent engineer on the project; you'll be the only engineer on the project.
RE: Delegation of Wind Load Calculations?
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RE: Delegation of Wind Load Calculations?
Spurred on by some of your comments, I've requested that a more strongly worded RFI be sent, pointing out the IBC and SJI Specification sections that say this info must be in the construction drawings.
If the architect refuses, I'll probably provide the calc with a lot of CYA and scope limiting language, and push for it to go through approval.
RE: Delegation of Wind Load Calculations?
RE: Delegation of Wind Load Calculations?
What is the difference between the supplier doing their own wind loads and delegating them?
I went to a seminar on deferred design a few months ago and was shocked on what was being deferred: Pretty much all those things and more. It seems that the EOR is more of a clearing house for deferred designs, hopefully assembling them into some kind of structure. The only saving grace is that, on these type projects, the EOR is still legally responsible for the total building. But the responsibility will get diluted with all these engineering entities involved.
RE: Delegation of Wind Load Calculations?
Construction Documents are defined as "Written, graphic and pictorial documents prepared or assembled for describing the design, location and physical characteristics of the elements of a project necessary for obtaining a building permit."
To be fair, it doesn't say who needs to put that information on the Construction Documents. Yes, it is typically the Designer(s) of Record. But in the case of trusses, as Jed pointed out, it's often "shown" in the truss profile sheets (which most jurisdictions require for permitting and are required to be kept on site at least until the framing inspection is complete).
Joists are a little different as you get into the Code of Standard Practice. You can deviate from it, but it should be made very clear that you are deviating and make sure that the contractor catches it. Doesn't sound like that was done here. And, unless I'm mistaken, the SJI COSP takes it a step further than the IBC and requires you to list net uplift on the joist, not just a generic C&C wind load schedule.
I hear you, and even had a client at my last firm ask me why he even hired us when he saw the list of things my boss decided we would defer on one of his jobs. But that's not my concern here. OP said that structural requirements were listed on the A sheets. That's fine if you're looking at a ladder or some little miscellaneous fabrication. But the roof joists? It sounds to me like there is no EOR to properly specify and manage those deferrals.
RE: Delegation of Wind Load Calculations?
This is a great chance to ask a question. SJI 200 Section 5.12 states "Where uplift forces due to wind are a design requirement, these force shall be indicated on the structural drawings in terms of net uplift in pounds per square foot."
I'm not completely sure I know what they mean by "net." My first interpretation was that they need the result of 0.6D+0.6W. So I was starting to try and figure out a dead load to use. However, "net" could also mean only the wind part: exterior suction plus interior pressures. Any of you have a thought on that, or better yet a reference with an example?
RE: Delegation of Wind Load Calculations?
RE: Delegation of Wind Load Calculations?
RE: Delegation of Wind Load Calculations?
I guess I'll have to do some explaining!
Thanks again everybody!
RE: Delegation of Wind Load Calculations?
RE: Delegation of Wind Load Calculations?