Without further definition, the member elements react linearly elastically in and about all assigned degrees of freedom in such analysis. Basically, this behavior is defined by Hooke's law: In this case, the deformation u of a solid is proportional to the acting load F, or its strain Δl depends linerly on the acting force F.
In reality, not every element reacts linearly and elastically. For example, a slender circular member, with regard to its cross-section resistance, absorbs more tension than compression. This property based on force can be conceived and simulated by means of member nonlinearity in the numerical calculation. In this case, the member strain depends on the acting force nonlinearly due to the premature stability failure (buckling) in the compression state.
Member nonlinearities exist in various forms. Usually, they do not depend on the forces relating linearly to each other, but on the final effect on the elements in the calculation.
Typical Member Nonlinearities
- Failure under tension
- Yielding when plastic resistance is reached
- Rigid from the defined deformation u
Entering in RFEM and RSTAB
In RFEM and RSTAB, member nonlinearities can be entered and defined graphically via "Insert" → "Model Data" → "Member Nonlinearities" → "Dialog Box," or manually by using the Data Navigator or the corresponding tables.
Arbitrary distributions of concentrated loads often occur in the load definition of beam structures.
The material model Orthotropic Masonry 2D is an elastoplastic model that additionally allows softening of the material, which can be different in the local x- and y-direction of a surface. The material model is suitable for (unreinforced) masonry walls with in-plane loads.
- When calculating a cable using the STEEL EC3 add‑on module, he error message "Incorrect characteristic stresses for material No. 1! Please correct this in Table 1.2." appears.
Is it possible to specify shrinkage effects as loads?
- Are the effective length coefficients in the add-on modules for the aluminum and steel design automatically determined from the model or do I have to make adjustments?
Which units are specified in the result display of the support reactions (kN or kN/m)? A note about this is missing in the graphic.
In the case that the support reactions are given in kN/m, for which distance does the value apply?
- I design a cross-section created in the SHAPE‑THIN program by using the RF‑STEEL EC3 add-on module, but the program shows the error message "ER006 Invalid type of c/t-part for cross-section of type General." What can I do?
Is it possible to calculate American steel cross-sections?
- Where do I find the setting to specify the entered structural component as a "wall" or "slab"?
- The four plates, identically loaded, show different negative moments at the point of support. Is this a mistake?
- How can I quickly model a chimney with reinforcement rings and stiffeners?
- The protocol lacks information on the limit time for the assessment of fire resistance R in the RF-TIMBER Pro add-on module. Can this information be added to the report?
Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements
The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions