Contractor using screw instead of bolt for connector 2

[Calc1]

I am dealing with a contractor that has placed screw instead of bolt for Simpson connector; he is telling me that it has enough capacity for the applied load.
I am not sure what should I respond to contractor, does he have any leg to stand on? If contractor does not follow the plan, is engineer still liable?

 

[henri2]

I assume here that you do not support what the contractor wants to do. Have you considered bringing this non-compliance issue to the attention of the building inspector assigned to cover the project?

 

[wes616]

Can't you simply compair the specs of the screw with that of the bolt. If it falls short, show the contractor this.

It's always better to argue someone's "opinion" with with facts on your side.

And if you find that it is equivilant, then you have an ace up your sleve for the next time.

Wes C.
------------------------------
There are no engineers in the hottest parts of hell, because the existence of a 'hottest part' implies a temperature difference, and any marginally competent engineer would immediately use this to run a heat engine and make some other part of hell comfortably cool. This is obviously impossible.

 

[IFRs]

How does he know what the applied load is? Is he an engineer? If the bolt was a through bolt, it is unlikely that the screw could develop the same strength as the bolt. However, if the load is low enough, the screw could possibly be strong enough. Check the 2005 NDS - they have all the info you need to calculate the screw and bolt capacity.

 

[archeng59]

does the Simpson connector allow the use of either bolts or screws? if so, are the allowable loads for each type of fastener (from the Simpson catalog) greater than the applied load?

 

[SperlingPE]

Liability issue:
If you know that construction was not done according to plans. You have an obligation to check construction for adequacy or have construction corrected to what is shown on plans.

Check the adequacy of the as-built construction. If not adequate insist that contractor make changes. If as-built construction is adequate, inform owner (& building inspector) that the contractor made a field change to the plans and that you have checked the adequacy of field change.

 

[bjb]

If the contractor is telling you that his deviation has enough capacity, tell him to prove it to you. You already designed it once, so if you have to check out this deviation, you should also get paid to do it. Why should you have to do free engineering for someone elses screw up? I would inform your client of what the contractor did, letting it be known that what happened was an unauthorized change by the contractor. Let your client know how much your fee will be to either check the adequacy of the change or to review any "proof" provided by the contractor. If your client (the architect?) seems willinig to let the matter drop I would let the code official know.

If the Simpson connector provided by the contractor has been fabricated for bolts (large holes), I don't think there's any way the connector assembly is going to be adequate by substituting screws for bolts. I would never approve it. Again, why should you accept the liability for something the contractor did that is not in conformance with your design? If this thing fails and someone gets hurt or killed you could be in for a lot of trouble.

It is the contractor's job to build the structure, not to re-engineer it. If the contractor wanted to substitute a different connector than the one you specified, the contractor should have requested the substitution in writing to you before building it. To sum up my wordy response, in my opinion the contractor doesn't have a leg to stand on. When I am made aware of an unauthorized substitution, I always make them remove it and furnish and install what I specified. If it's not feasible to do that, then I make sure that I get paid to engineer a fix for the problem the contractor created. The costs to implement the fix should also be the responsibility of the contractor.

 

[UcfSE]

Things like Simpson connectors are tested in a certain configuration that is then published with load values. If you change anything in that configuration, Simpson will tell you their load value no longer applies and you are on your own for whether the thing works. How do you know what the failure mode was that resulted in that published connector value? Maybe it was the bolt, or the yielding of the steel, fracture at the net section, and so on.

Bottom line, if he didn't install the thing correctly and there is nothing in the Simpson literature that supports what he did, I wouldn't except it.

 

[samdamon]

I agree with what Ucfse said. The capacity of most Simpson connectors is based on test data. If the connector is installed in any way that varies from the requirements given in the Simpson catalog, its unclear what capacity you actually have. As-built capacity might be roughly estimated using the NDS and your noggin as stated in the other posts above, but in the end not sure that approach would be defendable if something went wrong. Make sure you get compensated for spending your valuable time on this issue!

 

[Ron]

Calc1 - I gather from your question you are rather new at this. It's a good question and one that comes up routinely in construction.

As others have noted, particularly SperlingPE and UcfSE, there are practical and liability issues associated with such a review, evaluation, and response to the contractor.

If you are the Structural Engineer of Record, the you have already stated in the design what you want to see from the contractor. Contractors often substitute systems THEY deem to be "equivalent". Such "equivalence" must be proved by the contractor at his expense. This is probably covered in the construction contract. He's trying to substitute something that is less expensive for him and get you to approve its "equivalence" at no cost to him. Don't buy it.

Have him prove, through a licensed professional engineer and test data that the substitution is equivalent to your design. If he does so, then you can accept it with some level of RELIANCE on the other engineer (that helps your liability). If he does not do so, stick to your guns.

Ron

 

[Calc1]

Thanks everyone, How about even if you tell the contractor follow the CD and still does what ever he wants and city inspection approve it and the owner is noted of the problem, am I still liable and what are my options, how can I protect myself?

 

[UcfSE]

Write everything down, send everything certified mail, send letter to owner stating your concerns, save all emails and print for the file. I've never been in that situation so I have no idea how much you can really protect yourself but you can document all of your warnings and rejections. These are some of the things I would do. Certified mail makes sure you sent something and someone received it. They may even back off when everything starts happening in writing. Honestly, you can't go out there and build it for them but you can make it well known and obvious you do not approve and have such and such concerns.

 

[Calc1]

Thanks Ucfse for your inputs and others, I have never had this situation.
I have the note on the contract plan "The Engineer / Designer will not be responsible for any changes, deletions or substitutions of materials or methods without his prior written approval", I am fully relying on this statement on the contract plan to release me of any liability, but I have a note for Structural observation on the plan to call the engineer and that was the time I notice all the changes and wrote the letter to owner,I have given a letter to the owner of my concerns and release of liability and the owner said, he gave it to the contractor. I am not sure, if observation can cause any problem, was I responsible to check the job site all the time or the contractor was responsible to call me for observation and even observation makes you liable of his changes done?

 

[archeng59]

UcfSE is correct: documenting everything is key, especially if there is a "dispute" about whether or not the contractor is following the construction documents. it's my experience that the building official has no authority to allow something on the job that you are not approving the use of. doing so makes the building official liable for problems. create a field report stating what you saw, corrections that need to be made and any instructions for the corrections. make a follow-up visit and if the corrections were not made, create another field report. give a copy of the reports to your architect and recommend that copies of the reports be given to the contractor and owner. if there is a danger of structural failure, a formal letter to the architect is needed. it's my experience that the formal letter gets attention.

 

[AggieYank]

To me this is very simple. Just as bjb and UcfSE said, I would make the contractor do the following:

1) Remove the screw and place a through bolt.
Or,
2) Have the contractor fax me the information proving that the screw has the same capacity as the through bolt.

On something like this, he won't be able to come up with a capacity matching the required for the screw, so he won't comply with your request.

Tell him you will not be submitting a letter to the city or building inspector that the building was built to plan to the best of your knowledge. He can either change to the through bolt, or hire another engineer who is willing to stamp the design using the screw. This will be enough to make him change to the through bolt.

 

[FSS]

Call Simpson's 800 number and ask them. There is always a chance what contractor did is OK, although I can't imagine trying to put in screws through a much larger bolt hole on a strap and saying it is OK.

I have had numerous cases where Simpson engineers have given me some direction on whether to accept some of the more unusual substitutions that come up. Also, it gives them a heads up on who is using their products in a bad way.

 

[samdamon]

Calc1- Even if the township or city approved the construction, if you write them a letter specifically citing your concerns about this connection, they may back you up. They may have not noticed the change during their field reviews or are not aware of the issues we are discussing.

Fyi, have been in a similar situation twice. In the first instance, my office was thrown off the job by the Architect after writing the letter. Archie did not want to distress the Owner with the concerns that were raised. But we fulfilled our primary responsibility to the public by raising the concerns. In the second instance, the code official understood the concerns and required the Contractor to do what was asked of him on the drawings. Great deal of grumbling and consternation, but the building was done properly.

What I'm saying is that such a letter tends to get everyone's attention really quick. Just be factual and stick to your guns, and let the chips fall like they're going to. You know more about how this building works than anyone else.

Is there an Architect on the team? Is he listening to what your concerns are?

 

[archeng59]

if you are the PE responsible for the project (or if your boss is), you have an obligation to notify the architect, owner and building official if the contractor did something unsafe. I don't know if the use of screws versus thru-bolts is unsafe, but you should find out and address the issue. If the contractor mis-used the connector by installing the wrong fasteners, he is responsible for that and the architect/owner/building official need to know if the mis-use violates the code... i.e. the connector no longer has adequate capacity to resist the imposed loads.