Interesting customer projects designed with the structural analysis programs by Dlubal Software.
RF-STABILITY Add-on Module for RFEM
Stability Analysis According to Eigenvalue Calculation Method
The RF-STABILITY add-on module analyzes the stability of structures. The RFEM add-on module determines critical load factors and the corresponding stability modes.
- Calculation of models consisting of member, shell and solid elements
- Import of axial forces from a load case or combination
- Non-linear stability analysis
- Optional consideration of axial forces from initial prestress
- Four equation solvers for effective calculation of various structural models
- Optional consideration of stiffness modifications in RFEM
- Calculation of buckling modes of unstable models
- Determination of stability mode greater than the user-defined load increment factor (Shift method)
- Optional determination of the mode shapes of unstable models (to recognize the instability cause)
- Visualization of stability mode
- Basis for analysis using imperfect equivalent structures in RF-IMP
First of all, it is necessary to select a load case or combination whose axial forces are to be used in the stability analysis. It is possible to define another load case in order to consider initial prestress, for example.
Then, you can select the linear or non-linear analysis to be performed. Depending on the case of application, you can select a direct calculation method such as the Method by Lanczos, or the ICG iteration method. Members not integrated in surfaces are usually displayed as member elements with two FE nodes. These elements prevent from the determination of the local buckling for an individual member. Therefore, there is the option to divide members automatically.
Several methods are available for the Eigenvalue analysis:
- Direct Methods
The direct methods (Lanczos, roots of characteristic polynomial, subspace iteration method) are useful for models of small and medium size. These fast methods of equation solvers benefit from lots of the computer memory (RAM). 64-bit systems use more memory so that even bigger structural systems can be calculated quickly.
- ICG Iteration Method (Incomplete Conjugate Gradient)
This method requires only a little memory. Eigenvalues are determined one after the other. It can be used to calculate large structural systems with few stability modes.
The RF-STABILITY add-on module can also perform the non-linear stability analysis. Also for non-linear structures, the results close to reality are provided. The critical load factor is determined by increasing the loads of the selected load case step by step until the instability is reached. Nonlinearities such as failing members, supports and foundations as well as material nonlinearities are considered when increasing the loads.
- Direct Methods
The critical load factors are the first results displayed. They facilitate the evaluation of stability risks. In the case of member models, the module displays the effective lengths and critical buckling loads of the members in the second result window.
In the next result windows, you can check the normalized eigenvalues sorted by node, member, and surface. The eigenvalue graphics allows for the evaluation of the buckling behavior. The graphical display facilitates the provision of countermeasures.
Do you have any questions about our products? Do you need advice for your current project?
Contact us or find various suggested solutions and useful tips on our FAQ page.
Customers who bought this product also bought
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
Stress analysis of steel surfaces and members
Design of steel members according to Eurocode 3
Generation of equivalent geometric imperfections and pre-deformed initial structures for nonlinear calculations
Design of reinforced concrete members and surfaces (plates, walls, planar structures, shells)
Module Extension for RFEM
Extension of the modules for reinforced concrete design by the Eurocode 2 design
Dynamic analysis of natural frequencies and mode shapes of member, surface, and solid models
Consideration of nonlinear material laws
Seismic and static load analysis using the multi-modal response spectrum analysis
Reinforced concrete design according to the model column method (method based on nominal curvature)
Timber design according to Eurocode 5, SIA 265 and/or DIN 1052
Module Extension for RF-STEEL EC3
Warping torsion analysis according to the second-order theory with 7 degrees of freedom
Design of rigid bolted frame joints according to Eurocode 3 or DIN 18800
Physical and geometrical nonlinear calculation of beam and plate structures consisting of reinforced concrete
Dynamic and seismic analysis including time history analysis and multi-modal response spectrum analysis
Analytical deformation analysis of plate structures consisting of reinforced concrete
Design of single, bucket and block foundations
Design of connections with hollow cross-sections according to Eurocode 3
Soil-structure interaction analysis and determination of elastic foundation coefficients based on soil data
Design of hinged and restrained column base footings according to Eurocode 3