Application cases for variable cross-section shapes are the reinforcements in the area of frame joints, cantilevered members or slabs and towers with conical hollow sections.
Modelling in RFEM/RSTAB
A tapered member is modelled by defining different cross-sections for the member start and the member end. The cross-section type must be consistent, for example, I-shaped cross-sections at both member ends. To determine the member stiffness, the cross-section properties are interpolated using the member length. The interpolation can be adapted to the geometry of the taper: as a rule of linear distribution, the cross-section is only reduced or extended by the height. If the cross-section width is also changed, it is recommended to use the quadratic approach for the interpolation of the cross-section properties.
It is also possible to model surfaces as tapers by defining the surface thickness by three points as linearly variable. The definition points can be within the surface or even outside it as long as they rest in the plane of the surface.
You can design tapered members in the add‑on modules, such as RF‑/STEEL or RF‑/STEEL EC3, if there is a uniform number of stress points.
Under the links below, you can find the application examples for designs of a tapered member in the add‑on modules.
- FAQ: Design of Tapered Members with RF-/ STEEL
- Knowledge Base: Modelling Tapers for Hall Frames
- Knowledge Base: Determining Variable Cross-Section Depth of Tapered Member Using 'Connect Lines or Members'
- Knowledge Base: Design of Tapered Single-Span Beam According to Eurocode 3
- Knowledge Base: Design of Tapered Column According to EN 1993-1-1