East Coast Connection Design 2

[thoughtofthis]

Without getting into the debate a few posts below, I am interested in how your companies delegate connection design. Currently, we design shear type connections and provide loads for moment connections. For a variety of reasons, I would like to see us delegate more of this to the fabricator.

Internally, there is some resistance and I can only speculate the reasons; however, a well thought out work flow might help things along. I am interested in what works well and what does not. At what stage of the design in a typical Design-Bid-Build do you involve the fabricator? How does it affect your bottom line and does it contribute to everyone on the project being profitable? How does it effect your risk profile? How do you guard against liability issues with your loads being published on a drawing or spec? How do you handle a building that gets re-purposed later (potentially impacting loads)? I'm interested in the good and bad, but not interested in a debate on whether it should be an accepted practice. Thanks!

 

[archeng59]

Since I am the EOR on every project bearing my seal and signature, I am responsible for all connections whether I detail them or delegate to the detailer. For me, since I am responsible, I want to know what the connection needs to be before it leaves my office while the project requirements are still fresh in my mind. I know how many bolts are needed for each connection, what kind of moment connection is required and adequate, what kind of brace connection is required. I don't have to spend any time on the shops verifying the connections submitted. Just because there is a seal on the calculations cover sheet, that is no guarantee the designer detailed the connection correctly or detailed everything that needs to be detailed. The connection designer has an out if something is wrong: I reviewed and approved the connections. With that responsibility in mind, I design before the drawings leave the house. Usually, by the time I get shop drawings for review, I am working on another job and it takes time to refresh my memory adequately enough to review everything. Reducing my time in the shop drawing review phase helps my bottom line because I can get the shops in and out faster without impacting the new project.

 

[hokie66]

I have never worked for a company which delegated connection design, so can't comment about that method, other than to say I would resist. We show all repetitive connections with typical details accompanied by tables which group member sizes. All non-typical connections are then shown in detail...these generally consist of locations where several members intersect or overlap.

 

[rowingengineer]

My experience and opinion is the same as hokie's.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[StrPE]

While I am a connection designer, and thus make my living by EOR's delegating connection design, I still believe connection design should remain with the EOR and fully designed connections placed on the contract documents prior to final bid.
With that said I believe a system that has worked well is for the EOR to hire the connection designer up front to design the connections for them. That way the EOR gets the expertise of seasoned connection engineers, the connection engineer working closely with the EOR will fully understand the loads and load paths, the project benefits at bid time by all fabricators understanding fully their intended scope for connections thus all will be on equal footing, and the approval process goes more smoothly.
A major problem though with this approach is getting the owner to pay these connection design fees up front. The owner needs to be educated that they are paying the fees regardless of whether they are on the front end with the EOR or the back end with the fabricator, but either way they are paying. The savings comes in at bid time with the fabricators knowing full well what is expected. This process also helps to mitigate "extras" and law suits.

 

[frv]

In Texas it is almost always delegated to the fabricator to hire a connection engineer for all ordinary connections. Anything we want to design ourselves (for whatever reason), we will by cutting a section and showing the connection.

Unfortunately, most companies continue to specify the archaic note about designing the connection for 50% (or 55%) of the distributed load shown in the AISC Table. That, I think, is bad practice. I don't necessarily see anything wrong with delegating when connections are simple, but I think the actual loads should be specified on the plan to assist the connection engineer.

 

[hawkaz]

Can anyone say "Kansas City Hyatt"

I detail all my own connections. I don't ever want a gray area of who is responsible for what. If my seal is on the plans- the connections will be designed.

 

[thoughtofthis]

Hokie and rowingengineer:

The issue that I see where I work is not with connections for a 3 story office building, mall, etc., it is with the complex buildings with potentially thousands of connections and configurations. In such cases it is not as simple to have a table or typical detail saying all W8s to W12s have X connection. Fees are getting pushed lower and lower on these projects and it is increasingly difficult to be competitive with other firms that are delegating connection design.

STrPE:

Assuming a very progressive owner that accepted such terms, where would the line be drawn (no pun intended) as to shop drawings? Or did we just add an extra set of eyes and $? Also, on these complex projects where the arch or owner iterates the design 10 or more times, what is the benefit of having the connection engineer being involved through the iterations versus being on the back end? It seems that if the connections are done by the same group of professionals performing the shop drawings and the structural design is set (i.e.-no longer iterating), the process would be more efficient. I'm not criticizing the process, just trying to understand the benefits. Finally, in your scenario I assume the SEOR would not want to include the member loads on the drawings, correct?

 

[frv]

hawkaz..

That would be a good example of not an ordinary connection.

The advantage of delegating connection design is primarily an economic one for the owner. An experienced connection engineer will almost certainly be able to provide greater efficiency to the owner.

If I had to design each and every connection, you can be sure I'd take the worst case for each beam size and design all the connections for that capacity. It's not efficient, but our fees do not cover the expense of having me go through all of the beams.

A connection engineer has the capacity and experience to do it in a much more efficient manner than I can.

 

[StrPE]

Correct, if connections are designed and placed on the design drawings there is no need to indicate loads.
The iterative design process mentioned is killer to a connection designer. At some point, which may differ from job to job, the designs should try to be "frozen" so that changes can be minimized yet connection design can progress forward to meet schedule demands. Otherwise, you are correct again, money is wasted.
Most connection engineers are not detailers therefore do not produce shop drawings; connx design is tedious enough. Leave the shop drawings to detailers and leave the connection design to engineers.

 

[Teguci]

I have always felt the reason for allowing the fabricator to design the connections is for flexibility in the detailing. Perhaps the fabricator prefers a seated connection (faster placement) or a double angle connection (fewer bolts). By giving the fabricator guidelines and not details, he can select what he wants to use and potentially save cost. If we call for 3/4" Dia. bolts with a single angle connection, then, yes, we should finish the detailing and not trouble ourselves with the additional review and cost for a connection engineer.

 

[rowingengineer]

thoughofthis,
I dont compete on fees, most of my client retain my services for other reasons.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[hokie66]

thoughtofthis,
You have made my case. Complex buildings are exactly where the EOR should design the connections, as he is the only one who knows how the whole structure works.

However, I will admit that having never tried this system, I can't argue many of the issues intelligently.

Low fees are a separate issue...I think abdicating responsibility for critical elements of a structure is not the way out of that problem.

 

[idecharlotte]

I'm dealing with this right now. The owner wanted the least expensive design drawings possible for a somewhat complicated and unique structure. I told him he was going to need tons of connection details for this job. So I gave him a price to do the job without connection detailing and with detailing. He took the cheaper route and then when I finished said, "Oh by the way, we need you to go ahead and detail the connections and provide shop drawings because the local fabricator we are using doesn't have anyone that can do this." He actually thought I could just click a button on my CAD software that would detail all the connections and produce shop drawings and didn't understand why the price was going to double.

I like doing connection detailing if the client is willing to pay for it, mainly because I like to know that I handled the complete the design from top to bottom. But if they don't want to pay for it, I don't want to do it.

http://www.idecharlotte.com

 

[connectegr]

The Hyatt collapse is mentioned above. Not to deviate from the topic, but that engineer of record designed these connections also. And that collapse is a primary reason for the increased use of having an engineering specifically responsible for the connections and for having a second professional review the shop drawings.

As I have mentioned before, there are a long list of practical and responsible reasons for delegating the connection design. I would suggest discussing this with a firm experienced in the practice. There are several ways to address this delegation, but they are not all equally beneficial to the project.

http://www.FerrellEngineering.com

 

[hokie66]

The engineer for the Hyatt did design the hanger connections, and they were at best borderline. The detailer changed the connections, and in so doing halved the capacity. The engineer failed to catch the change in the shop drawing review stage or during construction. I fail to see how that case supports the arguments for separating responsibility for the structural steel design.

 

[connectegr]

Regarding your concern with the development of the design and changes...

This is always a concern when we work directly with design firms. Complex structures and architects always have changes and the design is worked through. In these cases a project can benefit from a large connection design team. A fast and efficient connection design process is important. Consideration for the connections can also result in minor design revisions that benefit the project. We have found that working directly with the designer has significant benefit on the project. Fabrication and erection budgets have less assumptions and can reflect major discounts. As mentioned connection design is a cost the owner will pay a some stage of the process. An educated owner benefits every time.

http://www.FerrellEngineering.com

 

[connectegr]

hokie66 and rowingengineer
I may make it a personal mission to change your position.

Post Hyatt collapse the intent is to have a second professional share the responsibility for review of the connections. A second set of eyes with a specific concentration on the connections. However, as with most things the practice falls short of the ideal. Many fabricators provide the very minimum and the advantages of participating in the design process are lost. Or the EOR provide insufficient guide for the connection design requirements and quality of calculations required. Calculation errors and approval comments, or lack of information create bad experiences for the EOR. There is a professional and high quality way to delegate connection design. Done correctly the project benefits because the design product is better.

http://www.FerrellEngineering.com

 

[hokie66]

connectegr,

Probably not worth your effort, as both rowingengineer and I practice in Australia, and your approach is unheard of here, as far as I know. We do delegate certain structural tasks, but generally have a different way of doing things than in the US. Structural steel in buildings is for the most part only used for the roof structures and wall systems of low rise buildings, and we have architects who present some weird challenges in those areas. Most of our multi-storey buildings are reinforced concrete, with a lot of post-tensioning, and the PT is sometimes subbed out, although I am one who resists that method.

We don't use bar joists, metal deck diaphragms, PEMB, and a lot of other things common in the US. I had a big learning curve when I first came to Australia from the US, as the predominant vertical load was uplift rather than the snow load I was used to.

Another thing different in the way we present designs here...the structural drawings show very little in the way of dimensions, instead depending on the architectural drawings. I don't know how they do it sometimes, but the steel detailers seem to be able to work out the structural dimensions. Fabricators do constantly complain about the quality of drawings they have to work with, so I am sure they don't want the added task of designing connections.

 

[connectegr]

Hokie66
We have worked with a couple detailers in Australia and New Zealand. But come to think of it, never on a local project. I have reviewed some excellent connection design research from Australia, that later was incorporated in some AISC examples. Australia is at the top of my list for a future vacation. As a diver and golfer, I would probably do very little connection design if I lived there.

Thoughtofthis
Sorry, I am not hijacking your post. I do know a good resource if you want to discuss the pros/cons of delegating the connection design.

http://www.FerrellEngineering.com