This TechNote pertains to the direct one-way link from Ram Structural System into Ram Elements. For information about using ISM to synchronize products, see Integrated Structural Modeling.

Importing a RAM Structural System database file into RAM Elements

Importing

1. Open RAM Elements Go to File (e menu) > Import > RAM SS (full model)… -or- File > Import > RAM SS (lateral model)…
   1. “Full model” is referring to all the members in the RAM Structural System that are flagged as “gravity” and “lateral”,
   2. “Lateral model” is referring to only the “lateral” members being imported. When the lateral only model is imported, the members that were defined as lateral are loaded based on the RAM Gravity analysis (see What’s Imported > gravity loads below), and in addition to the directly applied loads, the gravity member end reactions will be applied to the lateral members as point loads.
2. Browse to Find the RSS model, select it, and click [OK].
   1. The RAM SS file must not already be open.
   2. The version of the model must match the currently installed version of RAM SS.
   3. It may take a minute or a few minutes to import the model.

General Notes on Importing

Foremost, RAM Structural System divides the model in gravity members and lateral load resisting members. In RAM Frame, gravity members transmit only vertical reactions to the supporting lateral members and provide brace points). They do not get considered further in the RAM Frame analysis. In Ram Elements (Ram Advanse) there is no separation of gravity and lateral members and the behavior of the structure is analyzed all together (when the full model is imported).

What’s Imported?

Nodes, Members and Shells 

•  All member geometry, beams columns and walls. Note, the Axes in RAM Elements (Advanse) place the Y direction up, so the node Y and Z coordinates between the files will not match.
• Member sizes when section labels exist in RAM Elements (Advanse) Section tables. For steel members there will typically be a match. Be careful with double angles as the separation between the angles is not imported. 
• Member materials when materials exist in RAM Elements (Advanse) Material tables. This typically works for Steel and Concrete but not for Joists, Smartbeams or "Other" materials in RAM SS.
• Member fixity for members defined in RAM Structural System as Lateral. All imported gravity members will be pinned in the major and minor axis at both ends. In some situations this can result in a nodal instability in RAM Elements (Advanse).
• Horizontal rigid diaphragms. In RAM Frame horizontal diaphragm constraints can be assigned to sloping levels. This is not allowed in RAM Elements (Advanse). If the nodes assigned to a rigid diaphragm are not at the same elevation in RA you will get an error.
• Walls are imported as shells and openings in walls are also imported.

Loads

• Point loads on members.
• Line loads on members.
• Surface loads are not directly imported, rather they are distributed to members based on RAM Gravity, which calculates the tributary areas and attributes gravity loads to each member based on the deck orientation, and surface load applied to the deck area. This also applies to point and line loads applied directly to the deck in RAM SS.
• Vertical loads on walls from the deck, beams or line load are imported, but RAM Elements (Advanse) cannot apply a load to the edge of a shell, so these loads are translated to the corners of the walls. This can be unconservative in the analysis and design of the wall, especially if the wall is subject to beam bending, like a lintel.
• If the self-weight is indicated to be included with the gravity dead loads in RAM Structural System, then the self-weight gets applied in RAM Elements (Advanse) within the Dead Load case as follows:
  • Uniform load on beams
  • point loads on ends of walls
  • point loads at the top of columns
• All live loads (reducible, un-reducible, storage, roof) or snow loads get imported to RA as a single load case defined as Live Load.  See more about live load reduction below.
• Wind and Seismic Load story forces are imported as node loads. Special nodes are created for this purpose and assigned to the appropriate diaphragm in RAM Elements (Advanse).

What’s Not Imported?

Nodes, Members and Shells

• Member sizes or materials when no such section or material exists in the RAM Elements (Advanse) databases.
  • Joists size labels and material labels will be indicated, but these are not available in RAM Elements (Advanse). Some other prismatic section and material will have to be assigned to every steel joist in RAM Elements (Advanse). 
  • Concrete members sections are not based on the dimensions entered in RAM SS. They are based on the “labels”. The section size is only imported when the Section Label (from Concrete Beam/Column Section Properties in RAM Modeler) perfectly matches the section names in RAM Elements (Advanse) (i.e. "RcCol 18x18in"). 
  • "Other" material sections are the same as concrete members.
• Composite beams. The section size is imported to RAM Elements (Advanse), but the composite properties and studs are not, so the bare beam in RAM Elements (Advanse) will likely fail any code checks. 
• Member fixity for gravity concrete or other members are assumed to be pinned at each end regardless whether they are fixed or pinned in RAM SS.

Loads 

• Partition Live Loads are not imported.
• Lateral story forces other than Wind and Seismic loads are not imported.
• Lateral nodal forces from a Pseudo Flexible or Semi-rigid Diaphragm analysis in RAM Frame are not imported. Instead of the distributed loads based on percentages identified in RAM Frame Pseudo Flexible Diaphragm Properties, the original lateral story force is imported along with a rigid diaphragm assignment
• Nodal loads applied in RAM Modeler are not imported.
• Dynamic Load Cases are not imported. You can perform a dynamic analysis in RAM Elements (Advanse), but the nodal masses and response spectrum data must be entered again.
• Notional Load Cases are not imported. 
• Center of Rigidity Load Case is not imported.
• Virtual Work Load Cases are not imported. 

Other limitations and differences 

These differences can significantly affect the results, even for a model that is imported into RAM Elements (Advanse) from RAM Structural System

• Physical members: When partial floors modeled in RAM Structural System are imported to RAM Elements (Advanse), gravity columns that are continuous outside the partial floor (two story columns) will be segmented and a node created at the floor level. These members need to be unsegmented in RA, or at a minimum the end releases fixed at that node to prevent a local instability. Furthermore, the unbraced length of the column should be adjusted. Girders that form physical members are imported correctly, but it's critical that the option to Automatically segment members in RAM Elements (Advanse) is turned on or the secondary beams will not be supported.
• Live load reduction: In RAM Structural System all of the live loads are analyzed. Then, when performing a code check on a member the live load results (axial, bending, shear) are reduced based on the LL reduction % for that specific member. In RAM Elements (Advanse) this cannot be done so the external Live Load that is applied is all there is. If the live load is reducible, and if the tributary area of the directly loaded member is large enough (i.e. the beam trib area) then a reduction will be made prior to loading this member, but no additional reduction can be made to the columns supporting these beams.
• Cracked section factors: In RAM Structural System, you can assign cracked section factors to columns, beams and walls. This property isn’t available in RAM Elements (Advanse) for walls. You should reduce the thickness or E value of the walls in RAM Elements (Advanse) if you want to be consistent. For beams and columns, an Ig effective stiffness factor can be defined, but this is not imported from RAM SS.
• Rigid end zones can be assigned in RAM Elements (Advanse), but this is not automated as it is in RAM Frame.
• Meshing: each program does it's own wall meshing and while they use the same meshing engine, you may not get the same results even when using the same desired mesh size.
• P-Delta, the programs have completely different methods of performing P-Delta analysis (RAM Frame - Global Stiffness method, RAM Elements (Advanse) - iterative method), and while RAM Frame includes AISC 360 options for direct analysis (Stiffness reduction, B1 and B2 factors, etc), none of these are in RAM Elements (Advanse).
• Multiple rigid diaphragms on a single floor in the RAM Structural System will be imported to RAM Elements (Advanse) with the same Rigid Floor #.
• Member Design parameters: none of the member design parameters like unbraced length or K factors are imported from RAM SS to RAM Elements (Advanse).  They need to be redefined in RAM Elements (Advanse) whenever the default value is not correct.
• Member self-weight: wall openings are accounted for in the self-weight calculation in RAM Structural System, but shell openings are not included in the self-weight calculation in RAM Elements (Advanse).