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Connection Design

Connection Design

Connection Design

(OP)
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.
 

RE: Connection Design

The 3 options provide great flexibility in connection design, and clearly set responsibility/boundary on each group involved. Looks good, especially it kept the SER stays on top no matter the option adopt.

RE: Connection Design

I agree with SteelPE that the connection design should be performed by the SER.  But that is not the way it is and, I suspect not the way it is going to be.

I have some concerns about the fairness of this excerpt taken from the document:

Quote:


Final Authority

The SER is identified as the final authority in the case of a dispute between the SER and the licensed professional engineer in responsible charge of the connection design
when option (3) is specified. This is simple and straightforward, and it is how it must be because only the SER has the full knowledge of the structure.
The fabricator's engineer should not be required to take professional responsibility for something he is forced to do by the SER.

BA

RE: Connection Design

The final is squarely rest on the SER, not the design PE/SE.

RE: Connection Design

In a competitive bidding situation, it should be specified which method should be used, otherwise you will get some SE's always going to option 3 so as to provide the lowest quote.

RE: Connection Design

For structural engineers in the Western States (seismic country), it is standard practice to design and detail all connections on the same construction drawing set as the framing.  In fact, half of structural engineers in California wouldn't even understand your question.

There are many examples, the Hyatt Regency in Kansas City (1981) to name a more common one, which demonstrate that when there is a disconnect between the member/framing design and their respective connections, construction problems are more likely.

RE: Connection Design

Yes, the Hyatt Regency collapse resulted in much of the format/logic of the AISC code of standard practice based on the following resulting judgement from the case:

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

 

RE: Connection Design

(OP)
Kslee, try telling a bunch of lawyers the final responsibility rest squarely on the SER.  The last thing I want is my fate decided by a lawyer.

RE: Connection Design

SteelPE:

I don't understand your argument, if there is a case the lawyer wants to bring to court, there will be a line of responsible parties. Your name will be higher on the list if you were the SER/EOR, for whom was hired to supervise/direct/approve the task was undertaking.

Your fate is at your own hand. If you couldn't agree with the SER/EOR on how to handle project matters, and wouldn't settle with yourself, try to get someone who has the authority/qualification to intervene, if that effort has failed, and you still couldn't settle with yourself, walk away. Once you have got your hands wet - perform design task, be ready to defend yourself, no matter who dictates the method.

I think the new proposal is fair and wise to set a single person up to take charge and full responsibility. It in turn protects you from being randomly picked on as sole defendent for work done by a team.

RE: Connection Design

I think the connections should be designed by the SER with input from the fabricator. Usually you will end up spending more time reviewing the connection drawings, and it is usually quicker to do it yourself (considering the number of load combinations to deal with etc.)

RE: Connection Design

It really depends on the size of project and number of beam-column size changes.

At where I worked, the moment and special connections are always design in-house. The fabricator is only required to provide shope drawings, and design those simple connections using given criteria and loads provided by us.

The third option shall be considered while dealing highly complicate issues, since the fabricator's engineers are highly trained in that area (connection & fabrication). they will be more thoughtful in constructability, and efficiency. However, communication throughout the design stage is crucial, it is not wise for the SER/EOR to review designs at completion only. The fabricator is part of the team, and his engineers should be treated (supervised) as in-house staffs.

RE: Connection Design

Connections by the fabricator is efficient and safe if the correct loading is given by the EOR.

RE: Connection Design

One problem with having the SER design connections vs. the fabricator's engineer is that fabricators have certain standards for clip angle sizes, stock plate widths and thicknesses, etc. They also may drill vs. punch, which can affect edge distances and gauges. Another variable might be available punch and slot sizes, and which ply the slot may need to be in to best fit their operation.

I could go on, but point is that the SER will usually be fighting the fabricator because the fabricator substitutes his own standards, or there is an increase in cost because the fabricator is forced to use the SER's details.

I see nothing wrong with delegating connection design to the fabricator's engineer, who must back up his design with the proper documentation. He is also another set of professional eyes reviewing the shop drawings for compliance.

RE: Connection Design

I feel confident that no matter which method is used, a good structure will result. I am more concerned with a competitor trying to undercut other bids by always using method 3 and the Owner being unaware that he is playing the game of shifting some engineering costs to the contractor(fabricator) so that he will appear to be low.

RE: Connection Design

As long as "I feel confident that no matter which method is used, a good structure will result.",  

In this case, the owner wasn't short changed with inferior design, the competator did job cheaper without sacrificing quality, then what's wrong to save the owner a few bucks? Maybe you shall adjust your game plan in order to stay in the game.

RE: Connection Design

kslee1000:

Did the owner really save money?? How?

The scenario jike is laying out is true. If you provide connection design services and your competitor is always choosing Option C, all other things being equal, his bid for Design Services will be lower than yours.

However, the connections have to be designed by someone. The difference is your competitor has moved some of the Design Services costs off onto the steel fabricator who must now include this cost in his budget.

All other things being equal, the bid for the steel fabrication will be higher for the owner if he chooses your competitor.

However, this is hard to expalin to owners who are not in the deisgn or construction buisness. All they see up front is an engineer offering design services for a lower price. And 9 out of 10 will take the seemingly lower cost upfront, not realizing they will pay for it later when the steel fabricators submit their prices. Since all fabricators must now submit bids including the connection design, there will not be fabricators submitting bids that include the connection design and ones who do not include this. The owner will not know that his decision upfront to choose your competitor is costing him now.

 

RE: Connection Design

Quote (lkjh345):

Since all fabricators must now submit bids including the connection design, there will not be fabricators submitting bids that include the connection design and ones who do not include this.
How is it that all fabricators must now bid connection design?  If Option 1 is specified, they should not include connection design in their bid.

RE: Connection Design

ikjh:

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, which I have never heard of. After the bid, the bider may elect to do itself, or sub-out, abide by the bid submitted.

RE: Connection Design

The bids and contracts are arranged different depending whether the project is:

design build
conventional design bid build
construction management
 

RE: Connection Design

(OP)
Kslee

That may be for larger projects but what about the projects where the fabricator is selected after the design of the building is completed?  I'm not sure about you but this is the way I have seen a majority of my projects go.
 

RE: Connection Design

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

RE: Connection Design

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.    

RE: Connection Design

Quote:

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.

 

RE: Connection Design

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.

RE: Connection Design

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.

 

RE: Connection Design

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.     

RE: Connection Design

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.
 

RE: Connection Design

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

RE: Connection Design

Earlier, JAE said:

Quote:


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

RE: Connection Design

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.

 

RE: Connection Design

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

RE: Connection Design

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

RE: Connection Design

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

RE: Connection Design

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.

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