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Re: CONNECTION DESIGN RESPONSIBILITY

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In some circumstances it can be really a mess. I worked for fabricator whose estimator missed note in specs by EOR (n.b. one of big one) that all connections have to be design be fabricator. Complex building, a lot of not standard connections, as usual not enough info about loads - result was some hundreds of pages of calcs. Because of lack of info on the drawings and no communication track with EOR (who wanted speak only to GC), project was seriously late.
I agree that good EOR will work with fabricator on design of non standard connections. My colleagues engineers-designers have not always enough experience what and how is possible to do. But they know much more about loads and a way they want the connection transfer the load.
Nothing can replace the good engineering judgment of EOR. It is true that depending of his equipment and shop procedures, fabricator could have some preferences in type of standard connections. As far as they are equivalent to required on contract drawings it should be not a problem. Rare cases when EOR stays with his solutions are caused be (in my opinion) even lack of shop and field experience or ...
The real problem is when fabricator has not an engineer in his staff and is forced to make not standard connections. EOR, please think about it in you spare time.
John W. S., PE


Slightly off topic, but I have had experiences where the fabricator will bid the connections based upon how they want to build the building, not necessarily what is shown on the bid structural drawings.  Its a competitive world for the steel fabricator, and they need whatever edge they think they can get, and not all fabricators will bid per plan (which doesn't necessarily make for a competitive bid being apples to apples).  The General Contractor may not be concerned whether the steel subs are bidding per plan or not and leave it up to the winning steel fabricator to convince the structural engineer to accept there proposed changes, otherwise the steel fabricator has to absorb the cost changes if the structural engineer is not willing to make the changes.  To say the least,this can lead  to a hostile situation between the fabricator and SER since the fabricator does not want to have to absorb any additional costs.

Michael Cochran S.E.


In a message dated 12/10/02 1:27:59 PM Pacific Standard Time, rpfennell(--nospam--at)doingsteel.com writes:

Many fabricators exclude modifications to the AISC Code of Standard Practice.   We do.
 
Pushing off the design of connections on to the fabricator is, in my opinion, laziness.  The SER is the best person to design connections, as he/she is the one with all the actual service loads.
 
As far as fabrication practices dictating connection design, that's not entirely true.  A fabricator will bid a job based on the connections shown in the design.  If the design calls for shear plate vs. standard framed connections, that's how it will be bid. If you are worried about making the connections more economical for the fabricator, give them a choice between bolted or welded clip angles.
 
The typical fabricator's estimator doesn't know much, if anything, about connection design.  This is most evident when it comes to moment connections to wide-flange columns.  If the design doesn't call for stiffeners or web doubler plates, the estimator won't take any off.  This can hurt the fabricator if they are required.
 
It is my opinion that the jobs with the least amount of problems are the ones where connection design is handled by the SER.
 
Rich