Webinar | Advanced Structural Analysis with RFEM 6 Python API

Different methods are available for calculating the deformation in the cracked state. RFEM provides an analytical method according to DIN EN 1992-1-1 7.4.3 and a physical-nonlinear analysis. Both methods have different features and can be more or less suitable depending on the circumstances. This article will give an overview of the two calculation methods.

Performing serviceability limit state design also includes taking into account the allowable deformation. Calculating the deformation of reinforced concrete components depends on whether or not the observed cross-section cracks under the applied loading. The governing control parameter in RF-CONCRETE Deflect is the distribution coefficient ζ.

For reinforced concrete components and structures whose structural behavior is significantly influenced by the second-order effects, Eurocode 2 provides the general method based on a nonlinear determination of internal forces according to the second-order analysis (5.8.6), as well as an approximation method based on the nominal curvature (5.8.8).

The aim of this technical article is to perform a design according to the general design method of Eurocode 2, using the example of a slender reinforced concrete column.

After the calculation, the module shows clearly arranged tables listing the deformation analysis results. All intermediate values are displayed in a comprehensible manner. Graphical representation of design ratios and deformation in RFEM allows a quick overview of critical areas.

Since the design results are displayed by surface or by point including all intermediate results, you can retrace all details of the calculation. The complete integration of results in the RFEM printout report guarantees verifiable structural design.

• Deformation analyses of reinforced concrete surfaces without or with cracks (state II) by applying the approximation method (for example, deformation analysis according to EN 1992-1-1, Cl. 7.4.3 )
• Tension stiffening of concrete applied between cracks
• Optional consideration of creep and shrinkage
• Graphical representation of results integrated in RFEM; for example, deformation or sag of a flat slab
• Numerical results clearly arranged in tables and graphical display of the results in the model
• Complete integration of results in the RFEM printout report

The "Nonlinear Material Behavior" add-on includes the Anistropic | Damage material model for concrete structural components. This material model allows you to consider concrete damage for members, surfaces, and solids.

You can define an individual stress-strain diagram via a table, use the parametric input to generate the stress-strain diagram, or use the predefined parameters from the standards. Furthermore, it is possible to consider the tension stiffening effect.

For the reinforcement, both nonlinear material models "Isotropic | Plastic (Members)" and "Isotropic | Nonlinear Elastic (Members)" are available.

It is possible to consider the long-term effects due to creep and shrinkage using the "Static Analysis | Creep & Shrinkage (Linear)" analysis type that has been recently released. Creep is taken into account by stretching the stress-strain diagram of the concrete using the factor (1+phi), and shrinkage is taken into account as the pre-strain of the concrete. More detailed time step analyses are possible using the "Time-Dependent Analysis (TDA)" add-on.