Sealed calculations for connection design 2

[bldgdr]

From reading the AISC standard of practice it appears that the industry would like the design engineer of record to provide basic geometry and load information to the steel fabricator so that the fabricator can use their experience to provide the most cost effective connection. However, the standard of practice indicates that once the engineer of record reviews the shop drawings and returns them without comment, the engineer of record accepts responsibility for the connection design. To me this is a conflict because, in my opinion based on a reading of most states licensing laws, the EOR cannot stamp (take responsibilty for) work not directly supervised by the EOR. Since the fabricator works for the general contractor this supervision does not occur. Therefore it appears that either the EOR has to provide all steel connection details, or has to require a professional seal from the fabricator. We have had significant problems getting fabricators to provide calculations and/or stamp connection submittals. I am interested in others experience.

 

[JAE]

We have gone the route of designing all the connections. In most cases, the "standard" connection is pretty uniform throughout the industry so the argument that you should leave the connections to the fabricator to get the most "economical" connection has not been convincing to me after I check many shop drawings from various fabricators and they all follow a very similar geometric pattern.

We set up standardized connections for various WF shapes and check these against the actual loading for connection verification.

 

[KarlT]

We actually always specify in our drawings and specs that it is the steel fabricator's responsibility to provide sealed shop drawings outlining the connection design, member sizes, etc.

When we review these drawings, of course our review stamp states that we are only ensuring the drawings meet our overall design intent. We will often see a note added to the fabricator's drawings stating that their seal is for "design of connections only". Therefore, although we review the connections, the responsibility for the design of these connections clearly lies with the person who sealed the drawings on behalf of the fabricator.

Now if wee see something that looks bizarre, like say a fillet weld where the root is going to go into tension, or a "moment connection" that we called up that doesn't look at all like a moment connection, we would question the connection and make them revise and re-submit.

 

[JAE]

KarlT - I note that AISC's Code of Standard Practice does not specifically recognize your method. It either has the Structural EOR design the joints - or has the fabricator detail the joints based on set criteria such as AISC's standard connections. The fabricator then submits the detailed connections for approval. No second engineer is involved. It even states that it is never the intent that the fabricator practice engineering.

The method of delegating design responsibility is really just a different method of contract whereby the EOR requires another engineer to practice engineering, develop the connections, and submit for your (the EOR's) review.

I don't have a real problem with this but it is exactly the method used by Jack Gilliam whereby the Kansas City Hyatt Regency collapse happened.

The outcome of that lawsuit, in the courts at least, was that the EOR can certainly delegate to another engineer the design of connections on a project, but he cannot delegate the responsibility for those connections....they will always reside with the EOR.

 

[KarlT]

Great points JAE. However, I have always thought it to be a better situation when another engineer gets involved at the fabricator's end, as this should if anything provide another level of checks and balances that the design is adequate.

The person stamping the steel connections should familiarize themselves enough with the contract drawings to ensure they are comfortable putting their seal on it. Sometimes they may notice something that appears incorrect (that a steel detailer may not pick up on) and they can flag it up to me. (I do sometimes make mistakes!) On the same token, while I don't calculate and verify every last connection, I do make sure that everything does look reasonable (from my experience). Sometimes I also find stuff that looks wrong with the connections, and I won't hesistate to question it.

Obviously experience allows a person to take a quick once-over at a set of drawings and spot something stupid. (I once was designing the precast for a subcontractor for a building and I noticed a pile cap that was cantilevering out to pick up a large HSS column on the structural drawings. Then I noticed the draftsperson had detailed the pile cap steel at the bottom of the cap instead of the top and bottom. I pointed this out to the engineer of record, and boy was he grateful.)

Regarding the Hyatt Regency collapse, that kind of stuff can be avoided by the proper checks and balances of shop drawing preparation and review, when it is done with more than just a rubber stamp on everything. It definitely still is my job to review the drawings in a proper manner however.

 

[bldgdr]

It is my understanding that it is appropriate for an EOR for a structure to provide design information to another licensed engineer who would act as a "specialy EOR" for the design of a component of the structure. The review of the shop drawings is to ensure that the specialty EOR interpreted the design information correctly. This is similar to bar-joist, metal deck, precast, cold-formed metal trusses, wood trusses or curtainwall systems.

I have a question from KarlT. Do you have any problem with recieving calcualtions or stamped drawings?

 

[KarlT]

bldgdr

I'm not sure I understand what you mean by your question?

 

[bldgdr]

In the past we have had drawings and specifications noted requiring seals on shop drawings and calculations. We then receive shop drawings with out seals or calculations. After we reject the shops, we get a full court press from the contractor, architect, and fabricator to accept the shops without the stamp or calculations. When we point out the notes on the drawings we are told it was not included in the project and that we are delaying the project, etc.

On other projects fabricators say they are just using tables and will stamp the drawings and not submit calculations.

In short, this requirement for fabricators connections seems to be problem. I am to the point that I resist using structural steel.

It sounds like our experience is unique and not typical.

 

[KarlT]

As much as I hate hearing all the whining about having to seal drawings and all the delays it will cause, etc, etc, I'm pretty stubborn when it comes to enforcing the requirements of the drawings and specs.

Typically on projects done in our city, the City will not give an occupancy permit until we (the engineer of record)have sent a letter stating that the job was constructed to the codes, specifications, and drawings, etc. If the contractor refuses to send me sealed drawings, then I refuse to give him his permit letter. If you set the proper precedent, expect crying and whining but from that point on they will know you expect what you asked for.

Locally, I only hear complaining if the contractor flat out missed the fact that they needed to provide sealed shop drawings for whatever products they are supplying. In any case I tell them it's still required and if the owner feels sypathetic then they may give them extra $ but that's between them and the owner.

 

[JAE]

KarlT - just curious as to the relative size of the projects where you require sealed shop drawings.

I can see that, for the larger jobs, requiring sealed shop drawings (i.e. requiring the GC to hire an engineer for connections) would make more sense - but with smaller projects, or projects where the connections are quite standard - it seems a bit much.

 

[KarlT]

I agree, the size of the project does sometimes dictate that we end up designing the connections. However, it is a locally accepted standard practice (here in Winnipeg, Canada) that all steel-steel connections are designed and sealed by the fabricator on jobs where steel shop drawings are required. I think that the fabricators would rather that we stay away from designing the connections, as they prefer their own methods and there are some differences in the way they approach things. (Some like single angle, some like double, some like side plate, etc.)

For the small stuff, we will sometimes design the connections.

 

[civeng]

Hi guys,
I'm a professional engineer for a structural steel fabricator in Quebec, Canada, and here at least, we are required to seal all shop drawings. The responsibility of the connections belongs to us. Sometimes we are required to submit our calcs sealed also, but this is on rare occasions. This is also required on really basic shop drawings of micellenaeous metal such as handrails.

Have a good one guys

 

[phdunn]

I have done a lot of work for fabricators where we have performed the function of being a PE for connection design. This is not a problem when loads are given, but too many EOR's require full capacity of member(OK when high seismic) when not required. We even had one EOR require full tension capacity in his columns! (I never heard of a building falling up!)

 

[jcox]

I've been on both sides of the issue having worked for different fabricators. Sometimes the EOR for the project designs the connections; sometiems the fabricator designs the connections. When you specify an AISC certified fabricator, I believe that the plant is required to have an engineer on staff. If the engineer doesn't have to design any connections ever, then that's a pretty easy paycheck. Some jobs I've worked on had some pretty specific connection requirements. Other jobs the EOR for the project required some very specific connections in some places, and in other places left design up to the fabricator with some general guidelines. I don't believe there is a perfect method for deliniating responsiblity in jobs. If the EOR for the project tackles designing all connections; that can be a lot of connections. If the project is large, invariably you will find that the EOR missed a few connections. Then if the project is already on a tight schedule, and you have to wait for a connection design...well you can see some of the pitfalls. Some jobs are pretty straight up and will never be a real problem.
I've worked other projects where the design was left to the fabricator, and the only criteria was use the AISC uniform load chart for capacities. Sometimes with a multiplier for composite construction. What do you do when you have a W8x10 beam that is 5 ft long? The capacity of that beam is pretty large, and the connection is impracticle. Then you have to use some common sense, even though you are technically not following the specifications.
My opinion is to provide the fabricator with enough information to design the connections and be willing to collaborate. Some connections/problems just don't come to light until the details are underway. If there are any strange or specific requirements for some connections, then specifically show those connections. I don't believe that the EOR should have do design every The EOR should still review the details and make sure they look right. Remember, if the building falls down, you and the guy who drove the lunch wagon will probably be sued.
Don't let a fabricator tell you that designing the connections wasn't part of the deal if it is clearly spelled out in the drawings/contract documents. They probably got the job by being the lowest bidder and beating out somebody who bid connection design into the cost. They're probably hoping for a change order to get their price up to where it should have been to begin with. You can always offer to design the connections if they are willing to pay your fee.

 

[bldgdr]

All these comments are good, but it leaves the problem that AISC recommends that the fabricator "detail" while the engineer maintains responsibility. I would like to see some movement to have them clean up this discrepancy so we all know what to expect when we submit and receive a set of construction documents.

Does anyone know of a good definition for "design" and for "detailing" that would help in this discussion.

 

[nymous]

In my case, I have peformed many calculations for steel connections, and then I submit the calculations for the EOR review and approval. But at the time that EOR approve shop drawings, he statements that his approval DOES NOT relieve the fabricator for his errors in DESIGN and DETAILING of connections, dimensions or sizes.
After EOR approve shop drawings, it can proceed with fabrication and re-submit ALL shop drawings adequately sealed.
Almost always, EOR provide a set of STANDARD DRAWINGS with general notes and basic schemes for typical connections, where number of bolts or dimensions of welds or plates are not mandatory. These items must be defined by the fabricator. The requirements for forces to use in the calculation of connections are defined as a certain % of total capacity of member. In vertical bracing, for example, the requirement can be the 50% of tension capacity for X bracing configuration. For chevron bracing, sometimes require 100% of the compression capacity or 50% tension capacity, the greater. Some EORs require the vertical bracings connections for the 100% of the tension capacity of bracing. For end beams connections: 75% of total shear capacity. But in case of struts or collectors it is better to be very careful with connections, principally when forces are not shown on design drawings.