sloping level

[David van Erk]

Maybe an oddball in any project because who would willingly slope his level so that very devious people can sue the designer for whatever malicious reasons they may have knowing of the sloping floor.
For now, I do. I'm working on a project where the building is almost a mile long and one end is about three yards higher than the other. It's hardly noticable and very much cheaper to build. When laying down a marble it wouldn't even start rolling, hopefully.

In Revit however I'm unable to slope the level on which I'm working and want my objects to snap to that level upon placing them. Instead I can make a sloped reference plane but this isn't snapped to when placing objects. I know there is a difference between strong and weak references, but so far I've been unable to set that in the ref.plane. I'm attempting this through the help manual but this refers me to an instance box in the element properties that seems to be non-existing. (maybe a bug)

I have sloped the floor and reference plane sofar and attached the walls according to it. But this will have to be done manually after placing each object and there's a long list of parameters that will keep on refering to the level instead of reference plane. Also the project team is simply to big to run around reminding everyone to "please do keep on attaching" for about six more years to come.

If anyone knows a way of sloping the level or may have suggestions I can try out it would be greatly appreciated. So far I've tried a whole lot of things but maybe I'm just thinking too hard. No, just tilting the screen a little bit doesn't work, I've tried that too.


Regards,

David


This message has been placed as a wishfull thinking too.

[Max Lloyd]

Sorry, but I've no idea how to help.

have to ask though: what building are you working on that is more than a mile long?

[David van Erk]

Yeah, gets you thinking huh :)

it's an Airport Terminal

[dcunningham]

As a follow-up to what Dave wrote (he sits next to me at work):

Yes, the building is about 4000 feet long. All of the above-grade portions of the building are designed to match the slope of the site (1/32" per foot), while all of the below-grade portions are flat. And all verticals are truly vertical. We need some way of documenting the fact that at column line E50 the ground slab is at +299'-3, and drops by 1-5/16" for each column bay you move east or west.

We've been exploring various ways of documenting the effects of this subtle slope on the building geometry (fairly complex in its own right) via AutoCAD, Rhino, Max, and now Revit. The juniors on the team are finally beginning to understand that you just can't mirror a column / truss assembly across gridlines, because the diagonal geometry is different.

We figured Revit would be perfect for something like this, but we're not sure how to proceed.

There are other problems with trying to document this building in Revit, but that will be the subject for another thread.

David

[aaronrumple]

Hummm.

I think I would indeed just have one level at the highest elevation. The Walls are no problem - just attach their base to the floor after they are drawn on the main level.

I assume on the elevation the windows and curtain walls wouldn't slope of course. So these can reference the main level just fine.

Doors would be the biggest trick. These will need to be moved down or they will leave a wall below the opening. Personally, I think I'd use the lowest elevation for each bay and give all the doors, furniture, fixtures and other elements a negative elevation offset. So what if a couple of doors are sitting 1/32" below the floor? Shouldn't be a problem.

So just place everything. Then grab them and adjust them all down by the same amount.

Or you could do one level per bay and work from that, but I'm guessing that would be a lot of levels. However it might help with the structural. Be sure to make the 3D extents for each level just cover the bay it pertains to.

Does the roof/floors above slope at the same rate?

[Steve_Stafford]

There is no way that I know of to slope a level. Whether you display a level or not all the objects will be associated with one.

You may need to use "dumb" annotation to get your intent across or use Reference Planes and annotation symbols to identify them. There must be other levels above? Are they sloping as well? If everything is parallel, so to speak, but sloped, perhaps you could document everything level and refer to the actual slope as required? I suppose that wouldn't help identify true column heights unless the foundations are also parallel.

[Dimitri Harvalias]

I agree with Aaron. The problems you create with a sloped level are too numerous to mention. First and foremost Revit won't allow you to dimension from a sloped line to a horizontal line i.e. the elements being dimensioned need to be parallel. If you did dimension something how would they know in the field 'where' on the slope you were dimensioning from?
I think I understand that your problem is not necessarily the dimensioning aspect because I am certain you would use an established datum (a level one) as a reference for dimensioning, but rather the modelling issues; wall attachement, doors floating above the floor, elements not sitting vertical etc.
If the floor is a constant slope then it should be easy to to place spot elevations at the bay gridlines in plan as a reference. For relating to all other elements I'd probably set the high point of the sloped slab as the level elelvation. Done this way any clearance issues would report the worst case scenario.
As far as wall attachment to the slab you could use a ref plane aligned to the slab and attach all elements to that or use the attach tool and use the slab. Either way it might be easiest to wait until walls are drawn, switch to an elevation view in wireframe, select the elements at the lowest with a crossing window and then filter out all but walls. Then you can attach base for all walls at once. With R9 I believe columns will also be able to attach so you could do the same for those.

[dcunningham]

Some additional information based on people's responses:

The building is approximately 95 structural bays long. There are four main levels plus roof which slope in parallel over the 4000' length of the building (none of the subterranean levels slope, although there are a lot of stepped slabs in various places). We briefly considered defining a different level for each bay to account for the difference, but decided that would just make a tremendously complicated project insanely complicated, and we're not yet ready to declare ourselves insane. (!)

Before we discovered Revit, the intention had been to work out the spot elevation of the top of finished floor at each column bay on the sloped levels, and embed that information in the AutoCAD grid file. Any slab elevations on the sheet would then be relative to the datum information provided. (Electrical substations, for instance, would be noted just as "-2'-0".)

We're just starting to look at the curtainwall details. I'm not sure what the designer intends, but we'll probably come up with a sill detail for the curtainwall system to accommodate the floor slope. The module is 7'-0" wide, so there's not as much variation to take into account as across a full structural bay.

We've got a whole list of things that a sloped floor makes more difficult to deal with (in the real world, let alone Revit-world): stairs, doors (especially undercuts on egress doors), escalators, bathrooms, interior finishes. I'm arguing strongly, for instance, against using much tile on any wall running along the "grain" of the building slope. ONLY the floors are sloped though; all vertical normally vertical surfaces and joints remain vertical.

Dimitri is correct that this is primarily a modelling issue, not one of dimensioning. For many design elements we were going to have to provide x,y,z coordinates even if the building were flat. We're confident that we can deal with all of the construction issues, we're primarily looking to Revit for an easier way to extract correct information.

Thanks all for your responses. I think we're going to have a long talk with Autodesk about this and related issues soon (they're aware of the project) to see what kind of assistance they can offer. The irony in all of this is that the firm has been looking for a Revit test-bed project for since last summer, and one of the most gnarly, difficult things we've worked on is the one trying to make use of it.

Dave (& Dave)

[aaronrumple]

Some additional information based on people's responses:

The building is approximately 95 structural bays long. There are four main levels plus roof which slope in parallel over the 4000' length of the building (none of the subterranean levels slope, although there are a lot of stepped slabs in various places).
I think I would have had the upper levels and roof level rather than slope and at least isolated the slope issue to the first floor - but of course I don't know all the issues.

[aaronrumple]

The irony in all of this is that the firm has been looking for a Revit test-bed project for since last summer, and one of the most gnarly, difficult things we've worked on is the one trying to make use of it.

Dave (& Dave)
Oh ya. Bad plan.

[dcunningham]

I think I would have had the upper levels and roof level rather than slope and at least isolated the slope issue to the first floor - but of course I don't know all the issues.
Unfortunately, most of the levels are visually open to each other at various places, and there's no place in the design to hide the transitions--we're talking about thousand-foot long uninterrupted views down the main building axis. It was felt that the visual perception of a taper in height on the main Concourse level was bad.

As you say in the other thread though, the slope is almost the least of our problems.

Dave

[aaronrumple]

It was felt that the visual perception of a taper in height on the main Concourse level was bad.

Dave
Would you even notice it over such a distance? Would be interesting to compare two renderings.

[lafe]

You really wouldn't notice it.

Honestly, how many 35 foot buildings done by bad contractors have walls that are 2-4" out of square, and ONLY an architect could see that, and that only if he or she were VERY anal.

[PeterJ]

Yeah, gets you thinking huh :)

it's an Airport Terminal
Where is it, out of interest?

[tim.101799]

Unfortunately, most of the levels are visually open to each other at various places, and there's no place in the design to hide the transitions--we're talking about thousand-foot long uninterrupted views down the main building axis. It was felt that the visual perception of a taper in height on the main Concourse level was bad.

As you say in the other thread though, the slope is almost the least of our problems.

Dave

With that large of a building no one would ever notice. Come to think of it, with an open space that long, even if the floors are parallel to one another there will still be a visual perception of a taper.

[dcunningham]

Where is it, out of interest?
Umm, North America? (Sorry... :lol:)

As much as I would love to be able to tell you where the project is, who is involved, etc., I'm not at liberty to get too specific right now. And no, that wasn't a hint that it's Newark.

David

[dcunningham]

With that large of a building no one would ever notice. Come to think of it, with an open space that long, even if the floors are parallel to one another there will still be a visual perception of a taper.
That's as may be.. but if the floors are all parallel (albeit sloped) then all of the architecturally exposed structural steel can be uniformly sized. That's a significant consideration for a building this big.

David

[PeterJ]

Umm, North America? (Sorry... :lol:)

As much as I would love to be able to tell you where the project is, who is involved, etc., I'm not at liberty to get too specific right now. And no, that wasn't a hint that it's Newark.

DavidI was just curious. I work for an aviation house and I'm responsible at present for a bit of Heathrow and a couple of airports in Cyprus. We don't cover North America at present, though we are working with YVR, the Vancouver airport operators so you never know. Our growth area is the middle east.

Would I have seen your project at PTE? There were a number of speakers from American firms.

[dcunningham]

Would I have seen your project at PTE? There were a number of speakers from American firms.
I'm guessing the fact that I don't recognize the abbreviation probably means 'no'. The only published information about this project is from before the project was halted by September 11th.

We've done a couple of other airport projects, although not on the same scale.

David