Connection Design 1

[SteelPE]

I was wondering what the community thought about the proposed change to the AISC Code of Standard Practice Section 3.1.2, which allows the design of the connections to “be designated to be designed by a licensed professional engineer working for the fabricator”.

You can view an article here:

http://www.modernsteel.com/Uploads/Issues/May_2009/052009_connectiondesign_web.pdf

I personally think that connection design should be done during the design of the structure. There have been many times when I had to change beam and column designs to account for the required connections… especially with all the seismic design requirements.

I have also worked with fabricators before and getting reaction information out of engineers that is other than “the connection shall be designed for the maximum end reaction/moment” is next to impossible.

This is just my opinion and I’m sure many of you will disagree.

 

[jike]

I never heard of a fabricator working for the design team. The fabricator usually works for the GC or CM or DB.

 

[lkjh345]

Nutte and kslee:

I am laying out a scenario where design services are bid sepearte from construction services. This is still a common method of project procurement in some parts of the country.

In this scenario, the fabricator is not covered under the design services, and if the engineer chosen under the Design Service contract chooses Option C, the cost for the connection design will now be part of the Construction Servies contract. In this secarnio, all fabricators interested in biddding on the project will have to include the cost of connection design in ther bids, thus raising the cost of the Construction Services contract. But since there is no longer the option to bid the steel without including the connection design, the owner will not know the true cost of this service unless he asks the fabricator to breakdown the his bid.

 

[JAE]

The fabricator is under the design team's umbrella, his cost is included in the single bid (for over all, complete, design), unless the owner wants it be sperated

kslee1000 - I don't know where you are located, but in the US the fabricator is rarely tied in with the engineer of record - unless it is a design/build project.

What lkjh345 was simply saying is that if the original EOR requires the connection design by fabricator....ALL the bidding fabricators will include connection design and the owner will not "see" the difference in that contract.

If the EOR does all the connection designs, then the fabricators will not include connection design costs in their bids - and the owner again would not "see" the difference as everyone would be doing the same thing.

 

[kslee1000]

I don't do residential, subdivision, and commercial projects. But the contract situation should be similar with less lawyers get involved.

First, almost all design-build projects are covered by single bid.

Second, for design only, the level of design (either conceptual layout with member info & force diagrams/lists, or complete with details ready to be fabricated) and deliverables (Cals, drawings, specs) are either stipulated in the bid doc by the owner, or provided in the tender document by the design firms. Usually there is very little wriggle room for games, which would have legal consequences. Also, I am not aware of any reputable design firm would ever try to play games, as it would severely damage theirs reputation in the industry.

As the design firm, we employ all 3 options, whichever meets the contract requirement:
1. In-house design.
2. List all reactions required to develop simple connections. The fabricator is required to perform detailing (not design) per code specified, and furnish shop drawings for check/review over its accuracy and code compliance.
3. Engage a sub-consultant, very often it is a fabricactor with in-house PE/SE, to design the connections. The sub is required to perform detailed design, stamp, and submit the design for review. Its design then become part of the over all project design document, approved, and stamped by the SER/EOR.

The cost of options 1 & 3 are included in the single bid design fee structure. The 2nd is left to the fabricator, which should follow the industry norm for detail & fabrication efforts (no design).

For the 3rd option, the fabricator involved in the design may decide to bid for fabrication, for which he has inherent advantages - he has full knowledge of the project, and no need to waste time in detailing and further communication, as both are already done in the design stage, thus, his cost reduces to fabrication only.

Does the owner save anything? Judge yourself. I don't see the game, at least from the angle of design firm.

 

[JAE]

kslee1000 - For Design-Bid projects the fabricator has NO,....repeat NO contractual relationship with the engineer of record. The fabricator works as a sub-contractor to the general contractor who is bidding the project AFTER the design engineer has completed the design.

You say you don't see the game - the game that is mentioned above is where the engineer of record tries to delegate out some of the design effort (connections) to the general contractor which gets pushed on the fabricator.

For Design-Build - yes, you are correct that the engineer of record, the general contractor, and the fabricator all are under one "umbrella". But this is not true for Design-Bid.

 

[kslee1000]

JAE:

I don't know how you settle with the owner about contractural obligations - design extent, detail level, what to shown on the deliverables. At design-bid, the fabricator is not hired by the design firm for fabrication, it is still up to the owner, but sometimes it is hired as designer by the design firm as sub to facilitate the design/detailing, if the design contract requires such effort.

As I have alway dealt for design-bid that does not require detailing, we simple design all moment & special connections, then list reactions for fabricator to develop simple connections, which do not require design but use/follow the code. I think it is the norm.

Important thing is the design contract has to clearly spell out design extent/level/effort, and division of works (owner/design firm), which would protect both parties. I have never run into such case - once been awarded a project that requires complete detail (means the subs can develop shop drawings without engineer interpretation), then turn the head and say to the owner "you have to find someone to design the connections", since it is black and white in the signed CONTRACT.

 

[kslee1000]

Key words - "contract agreement". My personal experience, there were much fewer owner-design firm contructural problem than owner-contractor. The design firm simple has very few escape loop holes from legal stand point.

 

[kslee1000]

Seems there are more contract disputes between Architects & Design Firms, because of payment. I have no part of it, and no comment.

 

[BAretired]

Earlier, JAE said:

The engineer of record can delegate design to others but cannot delegate design responsibility to others.

That may true in USA but not here in Alberta. The SER requires that all connections be sealed and signed by an engineer retained or employed by the fabricator. It is clearly their expectation that the fabricator engineer takes full responsibility for connection design.

I am not complaining about that, just stating a fact.


BA

 

[JAE]

BAretired.

Hmmm... I would like to see the logic there. Here in the states, the design engineer of the connections still has liability for the design. That's not the issue.

The issue about overall design responsibility is that the EOR still has what you might call a "global" responsibility for the overall structure.

For the Hyatt Regency collapse, I believe that the judge in the case cited Jack Gillum (the EOR) for the ultimate responsibility in the case even though he (Gillum) tried to defend himself by stating that he had delegated out the connection design to others and those others had dropped the ball. The judge said that it was Mr. Gillum's responsibility to ensure that the various delegated roles were overseen by the EOR....thus my earlier comment about delegating design tasks but not overall responsibility.

But different countries each have their own legal history and perspective.

 

[BAretired]

JAE,

Perhaps there is not such a big difference in the practices in our two countries.

Engineering firms who insist on all steel connection details being sealed and signed by a professional engineer retained by the fabricator believe they are reducing their exposure to liability by so doing. They do not check designs which are sealed by the fabricator's engineer.

An engineer retained by a fabricator to design, seal and sign connection details is solely responsible for design and detailing of those connections.

In the event of a failure of a structure, evidence would be studied by experts and reported to the court. The court would ultimately decide where the responsibility lies. Because the legal profession has an imperfect understanding of what we do, the decision will not necessarily be fair, but we are stuck with it...at least until we appeal.


BA

 

[hokie66]

In Australia, having someone else take responsibility for connections is not an option. I don't think it should be.

 

[BAretired]

hokie,

I agree, but there are still members designed by the fabricator, i.e. steel joists or wood trusses. These also have to be sealed by their engineer. Is that different in Australia?

BA

 

[hokie66]

BA,

You are correct. There are certain building elements like that which we use in Australia. Timber trusses are one example where we require the supplier to have their engineer certify the design. We don't use bar joists, so that doesn't apply. We do use a lot of light gauge purlins, but we don't require individual certification of those, rather we depend on the manufacturer's load tables.

There is a trend here, which I abhor, and which has led to lots of problems, to sublet the design and construction of horizontal elements in concrete buildings, especially post-tensioned floors, which we do a lot of.