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.

 

[kslee1000]

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.

 

[BAretired]

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:

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

 

[kslee1000]

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

 

[jike]

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.

 

[ATSE]

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.

 

[JAE]

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:

[blue]The engineer of record can delegate design to others but cannot delegate design responsibility to others.[/blue]

 

[SteelPE]

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.

 

[kslee1000]

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.

 

[slickdeals]

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.)

 

[kslee1000]

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.

 

[civilperson]

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

 

[spats]

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.

 

[jike]

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.

 

[kslee1000]

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.

 

[lkjh345]

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.

 

[nutte]

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.

 

[kslee1000]

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.

 

[jike]

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

design build
conventional design bid build
construction management

 

[SteelPE]

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.