You can neglect openings with a certain area in the building model calculation. This function can be activated in the global settings of the building stories. A warning message appears saying that the openings have been neglected.
![KB 001860 | NBC 2020 Modal Response Spectrum Analysis and Base Shear Considerations in RFEM 6](/en/webimage/044604/3625998/Image_0.png?mw=512&hash=d87dc0138e82ba8cab464782074e5aa2b1fb3d3d)
![Building Model Add-on](/en/webimage/028467/3231624/1_en.png?mw=512&hash=fd421b3f2c85d04e163841c3e5995f948391dd20)
![Building Model Add-on](/en/webimage/025224/3154703/25224.png?mw=512&hash=f09d0c9ec35b2fb8547a76f0261b3b14941fdba3)
![KB 001880 | Design of Cable Structures in RFEM 6 and RSTAB 9](/en/webimage/049985/3840051/Seil_QS_EN.png?mw=512&hash=83dd891c6124be9c686441c4b37fe92db2c2062d)
![Feature 002632 | Floor Analysis as Detached 2D Structures](/en/webimage/041070/3545124/2023-06-22_15-36-36.png?mw=512&hash=1e094ee30f4d2d0a9c93f2cd5f456c9ba5c2afe0)
The building model is calculated in two phases:
- Global 3D calculation of the global model, where the slabs are modeled as a rigid plane (diaphragm) or as a bending plate
- Local 2D calculation of the individual floors
After the calculation, the results of the columns and walls from the 3D calculation and the results of the slabs from the 2D calculation are combined in a single model. This means that there is no need to switch between the 3D model and the individual 2D models of the slabs. The user only works with one model, saves valuable time, and avoids possible errors in the manual data exchange between the 3D model and the individual 2D ceiling models.
The vertical surfaces in the model can be divided into shear walls and opening lintels. The program automatically generates internal result members from these wall objects, so they can be designed as members according to any standard in the Concrete Design add-on.
![Feature 002664 | Modeling Tools for Building Models](/en/webimage/043816/3609974/43816.png?mw=512&hash=67e1752f5a2ba9fd3c557b17d484570ea5b74b01)
Several modeling tools are available for elements in building models:
- Vertical line
- Column
- Wall
- Beam
- Rectangular floor
- Polygonal floor
- Rectangular floor opening
- Polygonal floor opening
This feature allows you to define the element on the ground plane (for example, with a background layer) with the associated multiple element creation in space.
![Feature 002645 | Story Type "Load Transfer Only"](/en/webimage/042802/3572836/2023-08-15-07-31-40.png?mw=512&hash=9ae383438cc9e76b80eb19aae00cc8d2fa3b387a)
Using the "Load Transfer Only" story type, you can consider slabs without stiffness effect in and out of the plane in the Building Model add-on. This element type collects the loads on the slab and transfers them to the supporting elements of a 3D model. Thus, you can simulate secondary components, such as grillage and similar load distribution elements, without any further effect in the 3D model.
![Tabular and Graphical Output of Center of Rigidity](/en/webimage/035259/3420649/35259_EN.png?mw=512&hash=4e4e21315b3e0eea702bcfb0849dd9c5d805f306)
Have you activated the Building Model add-on? Very good! This allows you to display the center of rigidity in tabular and graphical form. Use it for your dynamic analysis, for example.