We are investigating functionalities of basic objects in BIM tools. Each BIM tool has different set of objects. One of the common basic objects is the wall, we assessed major BIM tools including Revit, ArchiCAD, Bentley Architecture, and Digital Project, focusing on these questions: 1. is a wall segment delimited to have a single floor plane?
2. is a wall also delimited to a single ceiling plane?
3. can a wall have non-horizontal changes in construction (through its cross-section)?
4. does the wall object support internal framing layout?
5. can a wall be a lofted surface, with a bottom curve and top (or intermediate curve) that is lofted between?
1. Is a wall segment delimited to have a single floor plane?
A wall can be split to two walls, and the thicknesses and height of split walls can be adjusted differently like a following figure. In this case, window can be inserted on the split line, and the thickness of the window automatically adjusted like following figure. With this behavior a wall can be stood on the multiple level of floor.
A wall can be split to several pieces of walls horizontally and vertically. Each divided wall can have a material. Thus, a wall could consist of several different materials by splitting the wall to several piece and assign different material on them like the figure 2.
2. Is a wall also delimited to a single roof plane?
A Wall to Multiple roof planes is also possible by splitting the wall to attach the multiple roof planes.
3. Can a wall have non-horizontal changes in construction (through its cross-section)?
As far as we tested, a slopped wall can not be built in Revit, and no information on slopped wall is in Revit help file and manual
4. Does the wall object support internal framing layout?
Revit does not have framing objects for structuring of a wall. However, revit can represent internal structure of a wall in the section profile. Walls, floors, ceilings, and roofs can comprise parallel layers; the layers can consist of either a single continuous plane of material, such as plywood, or multiple materials, such as gypsum board, studs, insulation, air spaces, bricks, and sheathing. Revit can represent each layer by setting the layer's material, thickness, and function. You typically see compound geometry in floor or reflected ceiling plan views and section views like following figure.
5. Can a wall be a lofted surface, with a bottom curve and top (or intermediate curve) that is lofted between?
Revit supports modification of a wall-elevation. The wall-elevation can be adjusted by using a command ¡°Edit Profile¡±, under options bar in the wall menu.
Edit Profile has sketch mode. With this sketch mode, user can draw the profile of wall-elevation like the figure 4.
1. Is a wall segment delimited to have a single floor plane?
No necessarily, building objects can be automatically trimmed by other objects in Constructor.
Objects such as wall, column and beam are automatically clipped by the intersect roof or slab. Most are unredoable to their original status except slab clipping, meaning slab is clipped without being able to convert back to its initiative status. Slop is another object then slab where slab is considered a single horizontal element, with or without openings. A step-like slab is a composite element by composing multiple segments as one grouped piece or alternatively, using a stair object to imitate a step-like slab. Wall, as a single piece, will be clipped automatically by a step or slope object if intersect.
2. Is a wall also delimited to a single roof plane?
Ceiling does not clip wall since wall, column and beam are mostly structural elements and ceiling is more likely internal features. Walls however can be automatically clipped by roof and slab objects.
3. Can a wall have non-horizontal changes in construction (through its cross-section)?
There are few constructors for special wall in ArciCAD, including:
a) Moldings and Panelings- Adding molding (e.g. crown molding) to a generic wall section;
b) Battered Wall - it is possible to construct a tapered wall in Constructor with layers of material; a battered wall differs to a lofting wall in terms of the constructing process. A battered wall is a special type of a lofting wall;
c) Canted Wall ? Canted wall is a special wall where it horizontal section profiles changes along the vertical extrusions. It is a type of a tapered beam.
As a summary, one can create a nattered and canted wall from a top and bottom loop (i.e. edge). It serves as a special constructor of lofting. According to the application documentation, battered and canted walls are manipulated by the generic wall parametrically through a tilting angle, causing a limitation on lofting through two arbitrary curves (more test needed regard to this subject). Walls can be constructed in layers of materials, both explicitly or by external references, for instance library items
4. Does the wall object support internal framing layout?
Constructor does support wall framing and its representations, meaning its layout is directly displayable to users. It will automatically generate studs-layout based on given parameters. It also knows how to calculate and adjust studs connection where opening such as windows and doors are in place. The result is to be sent to so-called Lumber-Pack for quantity takeoff. It handles some special stud designs including: double studs, cripples, jack studs, etc.
A BIM tool may support automatic stud-layout and calculation, but may not be necessarily displayable to user. For example a wall with layers of material may not need to be displayed with explicit layers in its graphic representation, but it does not mean that the application does not support it. It is a graphical issue rather then a representation issue for an application.
5. Can a wall be a lofted surface, with a bottom curve and top (or intermediate curve) that is lofted between?
No it does not support such a wall constructor especially for complex curves.
1. A single wall segment on multiple floor planes
Bentley Architecture does not support multiple floor planes for a single wall segments. Walls should be broken to two or more segments if we need to model on multiple planes.
Fig1. One segment of wall could not automatically be seperated by multiple floor planes.
2. A single wall segment on multiple ceiling planes
In the wall placement tool box, ¡°Top options¡± enable the designer to control the process and the shapes used to form the top portions of newly placed walls.
Fig2. Top options:
Top (option menu): Sets the method for creating the top of the wall.
- Fixed Height: the wall has uniform height; the top face of the wall is parallel with the bottom face.
- Connect Shapes: the wall is extruded so that the top connects to one or more 2D shapes.
- Connect 3 Pts: the top of the wall is located on an imaginary plane defined by three data points.
- Connect 2 Pts/View: the top of the wall is located on an imaginary plane that is constructed through two data points; the plane appears perpendicular in the view where it is constructed.
3. Non-horizontal changes in wall construction
Bentley Architecture does not support the non-horizontal changes on the wall surface.
Fig3. Bentley Architecture supports only horizontal changes like cutting profiles above
4. Internal framing support
Bentley Architecture supports wall assemblies (finishes) which are layered wall, but it does not support internal framing structure.
Fig4. Bentley Architecture supports just outside of wall assemblies and finishes
5. Lofted wall
Bentley Architecture partially supports topological control of objects, and linear wall objects could be modified by this control. However, curved wall could not be changed because it alerts that operations will parametric forms to non-parametric Triforma Solids.
Topological Control of solid models gives designers the ability to control the vertices, edges, and faces of objects in the model. Because topology operations are supported by selection sets across multiple objects, designers can select many vertices to move, rotate, copy, or insert into a model in a single operation.
Fig5. Linear wall could be modified in its topological form
0. Defining a wall object
Wall object is defined with 2 parameters, support curve and top plane.
The support curve is defined with one of 2D curve, 3D curve, line, spline, sketch object and other
curve objects. The support curve can include a segment that is perpendicular to the top plane.
Top plane is defined with plane or surface object. The orientation of plane can be rotated to X, Y,
and Z direction.
1. Capability to define wall with for sloped or stepped floor
By changing the support curve, wall can be a slopped at the foot side. By changing the top plane,
wall also can be a slopped at the top side. Wall with varying degree of slope can be defined in 2
ways. One is using cutting plane, the other is using curves with varying height. Image 1 shows a
wall with stepped floor using cutting plane and Image 2 shows a wall with varying height curves.
As the support curve cannot be perpendicular to the top plane, stepped floor is constructed with
two separate polylines.
2. Capability to define wall with changing ceiling height
Adjusting the wall height depending on changing ceiling height is achieved in several ways. The
first one is using cutting plane, the second method is using multiple planes, and the third method
is using surface. The third method cannot create a curved ceiling because of the nature of a
plane, which is always flat. The second and the third method have other limitation. In the digital
project, the wall object uses ¡®WallSupportSurface¡¯ to create a wall object. As a result of this
mechanism to define a wall object, the height of the wall is not adjusted to the exact ceiling
height. This causes problem in the following cases. Image 4 and Image 5 are zoom-in of Image 2
and Image 3. The height for a wall is cut with cutting surface the wall is cut smoothly according
to the cutting surface, while the height for wall is defined with either surface or plane, the wall is
not cut smoothly, since the ¡®WallSupportSurface¡¯ is cut first and extruded to both sides.
3. Capability to define a wall with changing thickness
The wall object does not support defining a wall with changing thickness. User needs to use
other solid objects and treat it as a wall.
4. Capability to create non vertical or non horizontal patterns
The wall object does not have predefined patterning or multiple materials of wall functionality.
5. Capability to create detailing object
The wall object does not have any of predefined details functionality.
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