Location of stiffeners - Standard Detail Sufficient??? 2

[Sunrayman123]

Our firm, a steel fabricator, was given design drawings which depicted moment frame connections, which referred to a detail (which in plan view was (3) beams coming into a column beam) showing "pictorially" a stiffener to be welded inline with the flange of the beams. We welded stiffeners on the weak axis (north beam) directly across the flange.

But afterwards, the EOR said the stiffeners should have been welded straight across the strong axis beams "where that flange occurred". So if the (east-west) beams were a different size than the weak axis beam, the stiffener would have to be located at a different dimension, than across the flange at the same height every time.

Consequently, the EOR asked our client contractor to develop a chart listing and providing a specific dimension for each particular stiffener location depending upon the strong axis beam size.

Our FIELD REPAIR of these stiffeners was EXPENSIVE! And we feel according to the "AISC CODE" that it was beyond our understanding of the "typical" detail given, and not our responsibility to inquire presumptively where these stiffeners should be placed. Else why would the contractor's engineer have to develop a "chart" which we were never in possession of prior to the field discovery.

So, my question is...were we responsible to understand the "weak axis - strong axis" issue without any wording of such on the detail provided? Were we required to issue an RFI when it would have been presumptive for us to do so? We feel the S.E. is responsible and should have clouded or clarified the stiffeners location on the shop drawing submittal.

 

[JAE]

"...to issue an RFI when it would have been presumptive for us to do so?"

As an engineer, I would never consider it presumptive, but I would expect you to definitely issue an RFI if you weren't entirely sure what my plans showed. In fact, I have noticed in the industry that there are many more RFI's issued these days (which is a good thing for communication).

Having said that, I would say there is shared culpability here as the drawings weren't clear, but you also didn't ask....so both the EOR and you should have better communicated.

 

[dik]

any shopdrawings?

Dik

 

[Redfish205]

Let me try and under stand this:
The moment connections were intended to be at the beams framing to the column flanges.
You interpreted them to connect at the column web.
You call the plates stiffeners, were they in fact "paddle plates" to transfer the flange tension from the moment to the column?
First off, as a fabricator you should have sent RFI's to clarify this in order to give a proper bid to your customer, Having said that I have seen the quality of design drawing where the moment connections are not clearly labeled or spelled out. Following is a list of typical RFI questions concerning moment connections:
1) Is this a high seismic area.
2) What is the "R" value of the building.
3) Are the moment connections to be designed for full moment capacity of the beam.
4) Have the columns been checked for stiffeners and doubler plates.
5) Can you furnish the moments at the beam so that the connections can be designed.
6) Can bolted paddle plates be used in lieu of complete penetration welds at the flanges.
7) Does Fema 350 apply at the moment connectons.
8) Does AISC seismic provisions apply.

All of these are questions that I have seen asked in RFI's by fabricators in order to clarify drawings. Not to me I must add, but by myself as well as other connection design engineers. I dont mean this as it probably is going to sound but it sounds like your company hasnt done many jobs with moment connections.
In our part of the country, the fabricator is responsible for all connection design not specifically spelled out on the drawings.

 

[DRC1]

If you had a question, an RFI should have been issued. however if you did not have a question, and thought you understood what was the intended detail, then you do not have a responsibility to issue. Apperently there were shop drawings and this was an aproved detail. Since you believed you were supplying what was asked and not requesting a change, you had no obligation to cloud it. The engineer had the responsibility to catch it at that point. There is one engineer of record and he is responsible for the structure. Although he can come back now and say that is not what he wanted, he or the client should pay for the corrections

 

[Redfish205]

That does bring up a good question. You mention "field repair", Why was this not caught on approval or did the drawings not go for approval? If the EOR approved the drawings, then I would think he was responsible.