RF-CONCRETE Deflect Add-on Module for RFEM

• 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 RFEM printout report

The deformation analysis with RF-CONCRETE Deflect can be activated in the settings for the analytical serviceability limit state design in the RF-CONCRETE Surfaces module. You can also specify here the settings for long-term effects (creep and shrinkage) and for tension stiffening between concrete cracks.  The creep coefficient and shrinkage strain are calculated using the specified input parameters or defined individually.

You can specify the deformation limit value individually for each surface or for an entire surface group. The allowable limit value is defined by the maximum deformation. In addition, you should determine whether the design applies to a deformed or non-deformed system.

The deformation analysis according to the approximation method defined in standards (for example deformation analysis according to EN 1992-1-1, 7.4.3) applies to the calculation of so-called effective stiffnesses in the finite elements in accordance with the existing limit state of the concrete with or without cracks. These stiffnesses are used to determine the surface deformation by repeated FEM calculation.

The effective stiffness calculation of finite elements takes into account a reinforced concrete cross-section. Based on the internal forces determined at the serviceability limit state in RFEM, the program classifies the reinforced concrete cross-section as "cracked" or "non-cracked". If the tension stiffening at a section should be considered as well, a distribution coefficient (according to EN 1992-1-1, Eq. 7.19, for example) is used. The material behavior of the concrete is determined as linear-elastic in the compression and tension zone until the concrete tensile strength is reached. This is reached exactly in the serviceability limit state.

When considering the creep and shrinkage, the effective stiffnesses are determined at the "cross-section level". The influence of shrinkage and creeping in statically indeterminate models is not considered by this approximation method (for example, in the case of structures restrained on all sides, tensile forces from shrinkage strain are not determined and have to be considered separately). In summary, RF-CONCRETE Deflect calculates deformations in two steps:

1. Calculation of effective stiffnesses of the reinforced concrete cross-section assuming linear-elastic conditions
2. Calculation of deformation using the effective stiffness with FEM

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 facilitates a quick overview of critical or cracked 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.