Without the priority system the modeling of floors would require one of two methods:
Note: It is important that you do not abandon the process after pasting. Otherwise, you will have two supports below at various locations, which causes calculation errors.
Use a series of short straight lines to model any curve in the plan. Do not make the line segments too short or the mesh will become very fine in that region. This approximation should have negligible effect. This also applies to circular drop caps which have to be simulated using a multi-sided polygon.
Slabs that are continuous in plan will have continuity in structural behavior in the model, regardless of the elevations/thicknesses of the slab(s). This continuity occurs even if the slabs are at different elevations and are actually disconnected. The image below summarizes the behavior assumed in RAM Concept.
It is possible to model discontinuous slabs in the same model, but it requires a physical “gap” in plan to create this discontinuity. We recommend modeling any such gap at least 3" wide, as smaller separations can be eliminated during meshing. Another option is to use two separate RAM Concept models to analyze each floor.
Choose Layers > Element > Slab Summary Plan or go to the visible objects dialog box and check the "Outline only" option under slab elements.
There is no difference unless you modify their behavior. Refer to the RAM Concept Manual Chapter 18 "Defining the Structure" for more information. The main difference between beam and slabs is how they are modeled: a beam is modeled by clicking on two end points along its centerline and always has two parallel edges offset from centerline, while a slab area is closed polygon and can be any shape in plan.
There is no limit, other than the limitations of your computer. If you find the program performance too slow, consider any of the following to help:
This cannot be answered directly as it depends upon the structure and loads. The maximum is 32.8 feet (10 meters). To speed the analysis, it is useful to choose a coarse mesh for preliminary design and a fine mesh for final design.
If in doubt, you should investigate the effects of different mesh element sizes.
Depending upon the defined fixity, columns can provide rotational and lateral restraint. If the far end of a column is defined as a “roller” support (or both ends of the column are pinned) then the column does not provide any lateral restraint to the slab. Columns above the slab do not support the slab vertically, they can only restrain the slab rotationally and laterally.
Columns in Ram Concept connect to the slab finite element mesh at a single node located at the column centroid. They are not solid objects nor do they provide vertical support to multiple nodes. This is apparent viewing the Elements - Standard Plan.
As such, deflections in the slab start from that node and increase towards the face of the column. For small columns this may not matter much, but for large area columns this is significant.
To mimic the behavior of a stiff column support, we suggest modeling a thick and stiff slab object that overlays the column volume like a mini-drop cap. Be sure to assign a higher priority to this patch of concrete. It is recommended to model this patch with an elevated top of concrete elevation such that the slab centroid aligns with the mid-depth of the patch in order to avoid eccentricity at this joint.
The same approach could be taken for thick walls supporting the slab as well. A beam or slab object can be used there.
Note, in version 8.02 a feature was added to automate this process. Refer to Rigid Support Zones in RAM Concept.
The general preference is to model the beams through the column, extended to the slab edge since it best matches the built condition and how things are formed. Stopping the beam at the column centerline results in a slightly more flexible system.
Yes, if you select Shear Wall as a property. If the Shear Wall is unchecked then the slab is allowed to slip freely over the top of the wall. The walls rotational stiffness is independent of the Shear Wall setting; use the fixity settings to control the walls rotational stiffness about its longitudinal axis.
Wall elements can be used to model the stiffness and spanning ability of walls connected to the slab. Walls above behave similarly to beams in that they stiffen the floor. One could actually model the walls above the slab as beams instead, but it is not generally recommended.
Using beam or slab elements does have some advantages over using wall elements (“wall-beams”):
When modeling wall-beams above the slab, Concept interprets some of the wall element parameters differently than for walls below.
Wall-beam elements have one advantage over slab elements.
There is no restraint at the far end of a wall above. (Even if “Rotationally Fixed at Far End” is checked, it is ignored).
Rigid Support Zones in RAM Concept