Other Considerations When Importing Into RAM Concept

Document Information

Document Type: TechNote 

Product(s): RAM Structural System, RAM Concept  

Version(s): Various

Original Author: Bentley Technical Support Group

Other Considerations

• The locations of columns and wall cannot be changed in RAM Concept. If the support locations must be changed, the RAM Structural System model should be modified and re-imported into RAM Concept.

• Adjustments to slab areas and beam elements (geometry, sizes, etc) can be done in RAM Concept following import of the RAM Structural System model. Any change affecting lateral members may alter the load path of lateral loads and should also be made in RAM Structural System.

• Beams in RAM Concept are meshed with the slab. For continuous beams modeled in RAM Concept, it is not necessary to model the beams in segments from column to column. Meshing problems are often prevented by modeling continuous beams as one beam segment from outside face of the first column to the outside face of the last column bypassing each intermediate column. Beams modeled in RAM Structural System are modeled support to support. When the beams are imported into RAM Concept, they are brought into the program as segmented members between each support. In most cases, there will be multiple overlapping areas at the column (see Figure1 below). Since this can produce meshing errors in some cases, it is often easier to not import beams and then create them in RAM Concept after the model is imported and modeling as a continuous beam (see Figure 2 below). 

 Figure 1. Beams Segmented at Column After Importing.

 Figure 2. Model Beams as Continuous Beams in RAM Concept.

• The slab in the RAM Concrete and RAM Frame analysis is assumed concentric with beam elements (i.e. the slab passes through the centroid of the beam section). The slab in RAM Concept can be modeled at any elevation, and slab and beam systems will be imported with the slab at the proper elevations. In RAM Concept, the difference in centroid between the beam and slab element produces an eccentricity that will produce additional moments in T-shaped beams from the axial forces in the slab and beam elements. There is no eccentricity of axial forces in beams and slabs in the RAM Structural System model. Please see RAM Concept T-Beam and Axial Force for more information.
• SlabcrackedsectionfactorsinRAMSSareimportedandusedintheRamConceptSlabBehaviorproperties.WhenperformingacrackedsectionanalysisinConceptaspartofadetailedServiceDesignRuleSetoraspartofaLoadHistoryAnalysis,thebehaviorpropertiesfortheslabsshouldberesettostandardvalues(1.0)topreventdoublecountingofthecrackedstiffnessreduction.
• Currently, there is no way to import the results of a dynamic response spectrum analysis from RAM Frame into RAM Concept. There are two basic approachs to dealing with this limitation:

  (1) In RAM Frame, create an “equivalent” static load case using a User Defined Story Force, one that generates the same total shear at each level (usually determined from the building story shear report). Then import the reactions from this static load case into Concept.

  (2) In Concept, manually create a new seismic load case (Criteria – Loading – New, with type normal). On the load layers for that loading, add point loads (or line loads) based on the reactions from RAM Frame. Be aware, that a dynamic analysis, by default, produces forces all of like sign. If you are not already considering sign in the RAM Frame analysis (Criteria – General), we suggest you do so. Otherwise, manually establish the probable sign for each of the reactions so that the forces input into Concept represent a concurrent event.

  More Information

  Please see RAM Concept-RAM Structural System Integration for additional help links.