Coordinating with Structural: Best Practices?

[theoryshaw]

Curious to hear other's opinion is when it comes to best practices of coordinating with a Structural engineer's model. (could apply to other disciplines as well)

In your opinion, in developing CDs, is it better to 1) reference structural's model into an architectural model or 2) for the architect to have their own structural model, and use that for coordination with the structural engineers?

We're currently using the 1st approach, but experience the following problems...

As we all know, throughout the course of DD/CD the walls and steel shift constantly. Since we draw our details on top of a 3d views, the steel we cut through is rarely located properly. In this regard there's a lot of mind numbing coordination with our structural engineers to move the steel around so our details/sections look correct. To rectify this, what would you suggest is the best practice? (A) Only draw 2d detail (without 3d backdrop) or ( B) Don't reference structural's model, but model structural in the architectural model?

We hedging toward option (B), since we'd can easily change the steel in our model to make our details/section look correct. We would then use this architectural structural model to coordinate with the structural's structural model.

Curious to hear other's opinion.

Thanks Much, Ryan

[dkoch]

We link the structural model into the architectural model. On projects where there may be some concern over shifting structural grids (or where the architects want control over where column bubbles should be located), we will copy/monitor the structural grids and columns. We generally find that by the time the architects are getting around to serious detailing, that the structural grid and steel sizes have more or less settled down. If there is a late change, it is more often initiated by the architects, rather than the structural engineers. I cannot recall a case where the structural engineer's model showed something either completely wrong, or that it took so long for the structural model to be updated based on an agreed change that it seriously impacted the architect's ability to develop plan details. For most of our projects, the structural engineering is done in-house, so getting the latest structural model is just a reloading of the link away. When using an outside consultant, with perhaps weekly model exchanges, I suppose the lag could be annoying.

Even a case where the steel design was changing and updated models were not instantly available, I would think that the effort required for the architects to create (okay, it could simply be a copy of the first structural model), maintain and manually coordinate a separate model would not be worth the minor benefit of getting the changed steel in the background of the details a few days sooner. Not using the structural model opens up the potential for your correct-looking details to actually be wrong, since the actual steel is going to be based on the structural drawings/model. If there are design changes and the steel moves, then your detail is going to have to change, anyway. If the structural engineers cannot be bothered to show it correctly initially, or provide updates in a timely fashion, then it may be time to find new engineers.

I would think the above would be more of a concern with other disciplines. I have had more problems getting a mechanical or electrical engineer to locate ceiling devices accurately than I have had with structural engineers. In the mechanical and electrical engineer's defense, the issue is not usually a question of them being unwilling to place the objects in the ceiling grids accurately on initial placement; it is more likely to be an unwillingness to move them three or four (or more) times during the design and documentation phases as the architects move the grids around by minute amounts. This process goes better for all concerned if there is an initial discussion about general rules for locating the devices and grids and then everyone lives with some slightly uncoordinated items when there are minor grid location changes, until near the end of a documentation phase, at which point the grids are "frozen" and there is a coordination meeting to identify areas where the fixture locations need to be tweaked. That avoids wasting the engineers' time chasing an ever-moving grid and gets things to look right when it matters most, just prior to a major deliverable.

[Mike L Sealander]

All of our details (1-1/2" = 1'-0" and larger) are drawn with the model shown halftone, and right before we print we hide the model. This means we draw structural elements using detail components right on top of the half-tone model, and then turn the model off at the deliverable printing.
At first I was very hesitant to do this, since it seemed like a huge amount of drafting when the model was right there anyway. But, it's even more tedious to try to get your model to look good at such a high resolution. We model until the model looks good at 1/2" = 1'-0" for wall sections, and then stop. So, I guess I'm saying using the structural model for wall and building sections, and then let it go.

[greg.mcdowell]

So, I guess I'm saying using the structural model for wall and building sections, and then let it go.

I completely agree. I'm even suggesting to take it one step further and do ALL details in Drafting Views. You're going to hide the model anyway and it allows for details to be used between projects easier. I've done it on my last few projects and it's worked a treat.