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Up Topic Welding Industry / Inspection & Qualification / Moment Connections and Backing Bars...
- - By welderbrent (*****) Date 01-05-2011 00:03
So, I am on a job doing the inspections where the engineers called out single bevel groove welds with backing bars for the Moment Connections.  Welding Procedures are made up accordingly with two different types of Moments, Beam to flange of Column, Beam to extended plates from web of Column so it is like a beam splice at the flanges and a bolted web.

All of a sudden the engineers reject the welding procedures with the backing bars and say they want the joint backgouged and welded overhead.  I ask 'why would you do that?'  Won't go into the details of what happened.  Needless to say I now have some questions that the rep from the engineer won't and Can't answer.

1) Does D1.1 2008 or 2010 REQUIURE backing bars to be removed, or not used in the first place, for a Moment Connection?

2) Does 2.17 Prohibited Welds  apply?  (I don't think so but I need help here)

3) Is a Moment Connection always and automatically a cyclic loaded connection?  My opinion is 'no' but I am not an engineer.  Help?

4) When the engineer calls out one joint design and then with the job in progress changes it, who pays for any added time? 

5) A single bevel groove weld with backing can have a much wider gap than without backing, since the members are already fabricated how do you adjust for the tighter tolerances?   The only thing I can see is to weld it with backing so the root gap can be wider and then not just backgouge but remove the backing then reweld.

6) If 2.17 doesn't apply, then where does it make it Required to remove or not use backing bars? 

I have both been the welder and inspector on many Moment Connections that were welded with either a single bevel or V with backing and the backing bars left in place and UT followed.  So what gives?  I'm now somewhat uncertain about this connection.  I know the engineer can call anything he wants, that is not the issue.  My question is, have I been misinformed and allowing a joint design that is not correct?

I have done a search and gotten a couple of ideas and information from past threads but not enough to satisfy my questions in full.  Please help. 

Have a Great Day,  Brent
Parent - - By Duke (***) Date 01-05-2011 01:36
RE: Q1- did the drawings or spec. mention D1.8?  If it did, then you will have to remove backing, backgouge and provide a reinforcing fillet weld at the BOTTOM flange of beam to column flange joints. Top flange, leave BB in place, and fillet weld at BB/Column flange.  My D1.8 is at site, this is off the top of my head.
Parent - - By welderbrent (*****) Date 01-05-2011 02:14
Duke, thanks.

As far as I can recall there was no mention of D1.8 in any part of the drawing's Arch Notes or Struc Notes or any specs.  That doesn't mean that that is not why the engineer suddenly changed the joint design.  It may have suddenly dawned upon someone that they missed something. 

These connections are already fit up per plans and WPS's.  Then the engineer sent out marked up WPS's changing joint design from single bevel with backing to backgouge to remove backing and weld from opposite side.  I told them we needed the RFI to also alter the print details or I still did not have a match to work with.  Just changing the WPS doesn't give the proper authorization. 

I know the engineer can call out whatever they want.  Especially since what they want is in no way OUT of code acceptable procedures.  I just want to understand some items more clearly.

Have a Great Day,  Brent
Parent - By 803056 (*****) Date 01-05-2011 04:40 Edited 01-05-2011 04:42
The structural design drawing should specify the appropriate codes on the notes page, usually the second (and third) page of the drawing package. The next place to look would be the project specification. The inspector needs to have both the project specification and the structural design drawings for review in addition to the approved shop and erection drawings.

The notes page(s) should reference AISC and AWS D1.1 as well as D1.8 if seismic requirements are applicable. Backing bars must be removed if seismic requirements are invoked or if the EOR requires them to be removed under the auspices of D1.1.

You should not involve yourself in any discussions regarding who is responsible for paying for additional work if you are the verification inspector representing the owner. Those decisions are up to the fabricator, engineer, and owner to determine. In general, if there is a change in the requirements that was not properly addressed in the project specification or the structural design drawings, the owner is responsible to pay for the "Extras." The owner may then go after the structural engineer and the architect if it is determined the changes were the result of an oversight by either the architect or the structural engineer.

As the fabricator, I would definitely look to charge the owner for the "Extras" involved in removing the backing bars and back welding the root of the joint if D1.8 was not specified or if the connections were not clearly identified as cyclically loaded. Moment connections in a building are usually categorized as statically loaded and the backing bars are left in place unless the connections have been defined as cyclically loaded or architecturally exposed steel. The added work involved in removing the backing bars and back welding the joints involves much more time and labor than a standard moment connection. Part C of Clause 2 of D1.1 requires volumetric NDT for joints falling into fatigue categories B and C if cyclic loading is involved and CJP joints are specified. That means additional NDT is required that may not have been anticipated in the original bid. That would required the owner to pay for the extra work involved in preparing the joints for NDT, the cost of performing the NDT, any repairs required as a result of the additional NDT, and the cost of any NDT needed to reexamine the repaired welds. All of this can place considerable financial burdens on the owner.

Best regards - Al
Parent - By swsweld (****) Date 01-05-2011 04:47
Brent,
4) If there is no justifiable reason to change moment connection welds AFTER the submittals have been approved by the engineer...that should have happened before work began, then the engineering firm should be liable for extra compensation to the erector.  They might be able to convince the owner to pay for it if they can sell it to them but not likely. An erector might eat a dozen or two but not too likely to eat 100-200 moments and shouldn't have to if they bid it one way and the engineer changed it after contracts were signed. It does sound like something was missed and now trying to cover his/her tracks.

Was FEMA 353 Seismic Design referenced anywhere?
Parent - - By jwright650 (*****) Date 01-05-2011 12:17
Brent,
Was there any mention of BOCA in the contract specifications? If so, D1.8 or FEMA 350 will be invoked by that.

Several years ago our estimating department got a rude wake up call when they missed the reference to BOCA when they took the job off and estimated it as normal construction(especially since the project wasn't in an active seismic zone).
Parent - - By ziggy (**) Date 01-05-2011 14:30
A wise man once said 'to the making of many books (or codes) there is no end and much devotion to them is wearisome'.

That being said, when it comes to codes and specs here is a little bit of: BUILDING CODES a brief history (this comes from http://www.lib.berkeley.edu/ENVI/Codes.html)

* The Uniform Building Code was first enacted by the International Conference of Building Officials (ICBO) on October 18-21, 1927. Revised editions of this code are published approximately every 3 years.

* The California Building Code was approved and incorporated into the UBC in 1988. In California we use the California Building Code and San Francisco uses the San Francisco Building Code.

* The new national code is the International Building Code (IBC) first produced in 2000 by the International Code Council (ICC). It combines the three model building codes published by BOCA (Building Officials Code Administrators), ICBO (International Conference of Building Officials) and SBCCI (Southern Building Code Congress International). Check with the specific community planning or building department to find out which codes apply to your project.
http://www.iccsafe.org/

* The 2007 Triennial Edition of CCR, Title 24 (California Building Standards Code) applies to all occupancies that applied for a building permit and remains in effect until the effective date of the new triennial edition. Some codes available online as PDF files. Refer to the California Building Standards Commission. http://www.bsc.ca.gov/

It all has to do with the acronyms!

Current specs may invoke the "IBC" per the state the work is being performed in for the building code (all 50 states have adopted the IBC to one degree or another); wherein that code will defer to many more codes (such as AWS for welding, etc.). One of the important sections of the IBC is 17 - Special Inspections. If the EOR specifies the IBC, take care to understand the ramifications of IBC 17; and to determine when to take advantage of the exceptions within that section for fabricators (1704.2.2).

ziggy
Parent - By welderbrent (*****) Date 01-05-2011 14:54
Thanks Ziggy,

This is in AZ and a small community with no references to many of the CA code amendments or Las Vegas.  The engineers are in AZ, the Fabricator, the Gen Contractor, the QC managers.  We all have a pretty fair grip on what applies here. 

One thing I haven't mentioned, it is a hospital added wing for breast cancer care that is in a cul de sac surrounded by three sides of the existing building but not to touch or be connected to the existing building as it was not designed for that kind of additional load.

I think that is why there may be some invoking of wind and seismic that got missed originally when the plans were drawn that all of a sudden is being compensated for.  The new addition must be totally self supporting and not put any load on the existing under any circumstances.  I just found that out last night in a late and long conversation with the QC managers who hired me. 

Your run down is very well noted though.  That's why I do have copies of most of those.  Not all, some of CA is not critical to me.

Have a Great Day,  Brent
Parent - By jwright650 (*****) Date 01-05-2011 15:46
Excellent post Ziggy!
Parent - - By welderbrent (*****) Date 01-05-2011 14:45
Thanks Duke, Al, SWS, John. 

First, I was called into the inspections a little late.  They weren't even going to have shop inspections until the QC managers noticed the fabricator was not pre-approved and insisted on it.  I am going to have to look more closely but as far as my memory allows I have seen no reference to seismic codes per AWS D1.8 nor AISC.  John, I will look for that one. 

As Al has stated, I know my position as a TPI is to represent the customer and his rep, the engineer.  I appreciate the cautions that I sensed in getting involved with who pays what.

Many of my questions are for my own education, I hope and pray that I am not misunderstood by you guys nor the engineer on a job when I ask questions. 

The engineers rep, who I don't believe is an engineer but a project supervisor, insisted that D1.1 mandated the removal of backing bars on any Moment Connection and also stated that all Moment Connections were Cyclic.  I probably upset him by asking where that was in D1.1.  I did keep telling him that the engineers could call anything they wanted and I would inspect it that way.  I just wanted to know where for my own information/education. 
I understand that once you cross the line to D1.8 and AISC 341 (?) that things change.  But I haven't seen those references anywhere and he wasn't quoting from them.  Kept telling me D1.1 would not allow backing bars left in place. 

That is not how I see it within D1.1, 2.17, the section 2 cyclic chart, or anywhere in Clause 3 where it shows the Acceptable joints and the applied conditions, nor in Clause 5 for fabrication.

AISC Part 12 has some figures that also very strongly back the use of single bevel grooves with backing bars for Moment Connections.

SO...I was trying to see where these guys were coming from.  I think I irritated him.  Wasn't trying to.  Just wanted to see if I had missed something.  Even their original plans with their stamp on them called the joints out as single bevel with backing.  So then did the shop drawings.  Then, the WPS.

All of a sudden they send the WPS's back all marked up and state they want a different joint, one with no backing and backgouge.  I stated that means they need to RFI the drawing details as well because the WPS's won't match the drawings.  I seem to be irritating my customer.  But am I headed the right direction?  Isn't that how it should be?  They can't just redo the WPS's for a joint that is not what is called on the plans/details. 

If THEY (the engineers) are the ones who marked up, changed, and accepted the WPS's as per their mark up, can I ASSUME that they have automatically changed the joint for the plan details?  Sounds like a dangerous ASSUMPTION to me.

I honestly think they missed the fact that they wanted some seismic restrictions on this and are back pedalling all of a sudden.  Not that that is important.  At least it got caught.  And, I represent them.  I just wish they would tell me the real reason they want it changed instead of trying to convince me that D1.1 MANDATES no backing bar. 

And, other than because I tend to be too nosy, and like to know all aspects of what and why decisions are made a certain way, there are some points here I need to just bite my lip and ignore unless they offer information.

Rambled long enough.  I'll dig a little more through the plans and see if I can find reference to seismic codes.  I know there was nothing said about the moments being cyclic in the plans or details.  No mention till now of backgouging and welding after backing bar removal.  I looked pretty close everywhere.  Architecturals as well as Structurals and all the Gen Notes.

Thanks again, Have a Great Day,  Brent
Parent - - By 803056 (*****) Date 01-05-2011 15:40
My simple advice is, "Let the fabricator ask the questions."

Your job is to ensure the fabricator and the erector follows the approved drawings. You have already asked the important question of where it is specified the backing bars must be removed. Now the Engineer has been placed on alert. If he is smart he should be looking into the code a little deeper to see if they do have to be removed. If he has any experience he should recognize it isn't necessary or he will indicate why it is necessary. If he's a newbie he will become defensive and try to back pedal a little to cover his butt.

On the other hand, the fabricator is saying "Whoopee! We're going to be rich!"

More than one fabricator I've worked for depends on "Extras" to turn a tidy profit. As one told me, "I bid the job at cost. The profit is in the 'Extras' that are bound to come up." 

I was on one project early in my career that brought this to light. I was handed a set of revised drawings by the customer. When I went out on the site I noticed the erector was placing steel that was no longer required because of some design changes. I told the erector of the changes and told him he will simply have to remove the steel being placed.

His response was simple and clear. "Al, I am provided with a set of drawings by the GC. I erect what is shown on the approved drawings. Until I receive the revised drawings through the proper channels these are the drawings I work with. I get paid to put up the iron as per the drawing. I then get paid for the "Extra" of taking it back down and replacing it per the new drawing set. Until I get the new drawings, I work with these. I cannot work to your new drawings on your say so."

The fabricator was absolutely correct. Lesson learned.

If I were the fabricator/erector I would be double checking the project specifications and if the changes requested by the GC or the Engineer are not per the original drawings I would be having a conversation with the accounting department drawing up the invoice for the "Extras" requested by the GC/Engineer.

As the TPI, I would be requesting revised drawings from the engineer and the fabricator indicating the new requirements. Likewise, the engineer should be providing you with copies of the "approved" WPSs indicating the particulars of the new details.

It is a wise person that asks the right questions.

Best regards - Al
Parent - By welderbrent (*****) Date 01-05-2011 15:52
Very well put, and I hope learned, applied, and remembered.  Thanks Al.

Have a Great Day,  Brent
Parent - - By welderbrent (*****) Date 01-07-2011 03:41
Okay, a little update.

First, the Fabricator had a good conversation with the Engineer.  The Engineer reviewed my emails regarding the changes to the WPS's.  They decided to go with the original plan details and the WPS's as submitted.

They are still hesitant about rather the procedure will produce satisfactory results. 

The plans in no way in any place call out any thing that could be construed as referencing D1.8 or AISC 341 Seismic codes.  They make no reference to anything seismic in any other code or way.  They have no reference to Cyclic loading anywhere. 

So, they approved what was originally designed by them and approved when first submitted.  And there appears, from my point of view, to not be any reason for attempting the change anyway. 

I don't know what happened.  I do know I stepped on a couple toes.  I'll have to be more careful.  Because I am often on the other side as well, since I own my own welding/fabrication shop, I guess I let some of my curiousity get me too involved and I pushed too hard wanting to know WHY.  I have to be more disconnected from one when working as the other.  I can't be an inspector and a fabricator at the same time unless I already have a good working relationship with the Engineer and his people. 

At any rate, Thanks again for the responses and advice.

Have a Great Day,  Brent
Parent - - By 803056 (*****) Date 01-07-2011 06:43
Remember you represent the owner when acting as a TPI.

I had one client tell me, "You work for me, not the fabricator. If they need a consultant they can hire their own."

It can be difficult to keep yourself separated from the fabricator especially when you see them doing something stupid. However, when you start to tell the fabricator how to do their work, you become part of the problem. The fabricator has to solve his problems, the TPI has to protect the owner's interest.

Best regards - Al
Parent - By welderbrent (*****) Date 01-07-2011 14:01
Thanks Al, and for the record I was speaking mostly about my own conflict of interest, not because I was both fabricator and inspector, but in my mind I wanted to know some things because of the fabricator in me that was not my concern as the TPI for these Engineers.

So, I had a mental conflict of interest that I need to learn to curb.

But, you are so correct.  It is difficult to watch fabricators do stupid things and not jump in and help them.  But I am not on their side.  Even if they are not an Approved Fabrication Shop, they should still have the knowledge and resources and should have read the print pack at the least and the Job Specs as well and know what is expected of them and how to resolve any questions.  This also means that they should have some form of QC of their own.  I am not their QC in any way.  Only making sure their QC accomplishes the desired end product quality to the Codes referenced by the Engineers.

Have a Great Day,  Brent
Parent - By Joey (***) Date 01-12-2011 06:33
Is it the TPI has to work independently in accordance with contract spec / code requirements? Should it be…the TPI is to protect the interest of his company.
Up Topic Welding Industry / Inspection & Qualification / Moment Connections and Backing Bars...

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