Structural Engineering CAD files used by contractors

[archeng59]

During the last year or two, I have been asked to provide a copy of my CAD drawings to surveyors. They want to use the foundation drawings with their GPS-guided equipment. Is anyone else being asked to do this?

Also, the fire protection contractors are regularly asking for the framing plan CAD files to help with their designs.

This is a bit like the BIM discussions. In the future, how much more are others going to request our CAD files for their use? Should we provide them? Just wondering about other peoples' thoughts on this.

 

[lkjh345]

Archeng59:

FWIW: We routinely provide our CADD files to contractors, subs, and fabricators upon request. We first make the requesting party sign a waiver stating that the files are for the preparation of shop or layout drwawings only, and that the user is using them at their own risk, and are responsibly for checking all dimensional accuracies, etc.

Its a fairly tightly worded diclaimer and waiver.

We do not charge for the files.

 

[msquared48]

I would always be worried about someone changing the electronic files should a lawsuit emerge in the picture.

I would be very reticent to send out any electronic drawing files unless they can be locked against any changes and dated.

Mike McCann
McCann Engineering

 

[archeng59]

lkjh345, we have a strongly worded release statement that was based on a CASE document and was reviewed by our insurance company for potential liability issues. Part of the release states that the hard copy drawings bearing the seal and signature of the EOR are the legal documents for the project. The release states that the contractor shall not use the drawings for any other project or purpose. Alot of stuff like that. We remove all information about our company before sending out the drawings. I do not provide the CAD files to fabricators. We don't charge for the drawing files, either. We were told not to charge for the files because they could be considered a product and not instruments of service in the event of legal issues.

All that aside, I asked the question mostly to get a feel for how prevalent the sharing of files for use by various consultants/sub-contractors. Mainly besides steel fabricators.

 

[shin25]

Few months back, there was a lengthy discussion on a topic similar to your posting. Check the link -

http://www.eng-tips.com/viewthread.cfm?qid=199987&page=7

 

[FSS]

When asked for drawings electronically, we send them out as pdf's.

 

[lkjh345]

Archeng59:

Similiar to your OP, we have been getting more and more request from surveyors in the last 2 years. They plug the AutoCadd files into their total stations. They say it helps speed things up.

They need the elctronic files for this.

We routinely send them the files after they sign the release.

 

[RARWOOD]

Speaking from a glulam fabricator's point of view, being able to use the architectural and structural cad files can be very helpful and often will reduce the time needed for shop drawing preparation.

On many projects that I have been involved with the cad techs end up redrawing the exact details that have already been drawn by the architect and engineer. One thing we don't do is photo copy details from architectural plans and use them as part of our shop drawings. That practice seems to be wide spread among steel fabricators, although most specifications prohibit photo copying the architectural plans.

Having cad drawings of the architectural plans can also reduce the number of RFI's we submit. For over half the jobs we work on when we lay out the framing plan using the dimensions given on the architectural drawings, the building will not close.

It is not uncommon for us to send an RFI out questioning a dimension only to have the architect pull something off his drawing giving us a dimension that we know is wrong.

When we have the architects cad files we can go in and examine the layout and often resolve our issues with out sending an RFI out.

 

[Tomfh]

I would always be worried about someone changing the electronic files should a lawsuit emerge in the picture.

I would be very reticent to send out any electronic drawing files unless they can be locked against any changes and dated.

Anyone with half a brain isn't going to tamper with electronic drawings because they know they'll get busted, and anyone stupid enough to bother will be easy to bust.

 

[NITTANYRAY]

We charge $50 per drawing sheet. It would cost them 10 to 20 times that much to start from scratch. Some complain but they all pay in the end.
We always remove our seal before giving them to anyone.

 

[DonPhillips]

I would go further and remove not only the seal but the titleblock so they only get the model and very little in the file with your company name on it. Even if you erase things, make sure you purge the drawing to get rid of block definitions containing company identifying information.

Don Phillips

http://worthingtonengineering.com

 

[RARWOOD]

NITTANRAY Most of the time, $50 a sheet would be well worth the cost. The value goes up based on the quality of the drawings. I worked on a job about a year ago which involved a building with four or five roof planes sloping in different directions.

The building was laid out by the structural engineer. Although we didn't have cad files on this job we didn't need them. Using the dimensions on the drawing we built our wire frame and agreed with all the elevations the engineer showed on his details. The structural drawings were so accurate that we thought the engineer had used a 3-D cad program. We found out latter that he had just accurately worked everthing out.

As a side note I work on glulam shop drawings. The drawings included fabrication drawings for both wood and steel hangers. We send our Auto-cad files to our steel fabricators who in some cases will imput them directly into their c & c equipment. This was a big change for us because in the past we checked the dimensions shown on the steel drawings but not the cad files. Now on our steel weldments we have to check the cad files for accuracy.

 

[SperlingPE]

To charge or not to charge?

Charging for CAD files would make it seem like you are charging for a product.

What is our product as structural engineers?

If you don't charge for the files and they are used by a supplier to produce shop drawings, are you sure that this time savings (by the supplier) is reflected in their bid so that the owner actually saves money? Or did you just put additional money in the pocket of the supplier for no consideration?

I think these questions should be addressed in the spec's. If you will provide CAD files for supplier's use should be stated in the spec's. If there is a fee, that should also be stated.

 

[elliott54]

It seems there are 2 discussions going here: 1) collaboration (and related compensation), and 2) security.

On the latter issue, the federal government made file-sharing absolutely safe when they enacted E-sign bill years ago!

AIA promotes the practice of Digital signing (not the same as “digitized” signing). See the AIA paper “13.03.05 Electronic Data Transfer: Electronic Signatures” at

http://www.aia.org/bp_chap13,

and I’ve also attached it here.

When it comes to digitally signed files (whether .DWG’s or .DOC’s or Email messages), the authorities agree we are GUARANTEED that 1) the person (or business) that sent the file is who they claim to be, 2) the drawing has not changed in any way, either intentionally or accidentally, since it was signed, and 3) the signer cannot later disown it, claiming the signature was forged. That’s pretty iron-clad!

For example, AutoCAD (back to v2004) includes the utility (called “Attach Digital Signatures”) which really IS as easy and painless as the AIA says. You can get a free digital ID from

http://www.instantssl.com/ssl-certificate-products/free-email-certificate.html

or you can pay Verisign $20 at

http://www.verisign.com/products-se.../pki-application/email-digital-id/index.html.

At first glance it’s confusing because these appear to be just about Email. But these are actually just your required ID (like a digital Social Security Number), which support Email but also can be used to sign ANY file type as long as the host application (autocad, adobe, etc.) supports Digital ID’s. According to the AIA, a Digital ID is “simple, available, and inexpensive, and getting one takes about five minutes.”

Aside from the issue of whether or not you WANT to share the files, any 2 parties who DO want to can easily share files without any future worries of file alteration.

Does anyone know why more engineers don’t use Digital ID’s to practice (truly safe) file-sharing?

 

[DonPhillips]

Some states still require an old-fashioned stamp - like Michigan and West Virginia.

Don Phillips

http://worthingtonengineering.com