Considering Shrinkage

Tips & Tricks

000586 06/17/2013

Shrinkage and creep are time-dependent deformation properties of concrete. They usually have to be considered in the serviceability limit state design.

Concrete shrinks during hardening and drying. This results in a shrinkage deformation, which is described by the total shrinkage strain εcs. The total shrinkage strain consists of the autogenous shrinkage εca (basic shrinkage strain) and the drying shrinkage εcd.

In the RF‑CONCRETE Surfaces add‑on module for RFEM 5, it is now possible to consider the shrinkage of the concrete directly in the module.

To do this, you have to activate the shrinkage in the settings for the serviceability limit state design. For the analytical method of the serviceability limit state design, you need the RF‑CONCRETE Deflect add‑on module; for the non-linear calculation, you need RF‑CONCRETE NL. If shrinkage is activated in the settings for the serviceability limit state design (in Window 1.1 General Data), the “Shrinkage” tab becomes available in Window 1.3 Surfaces (see Figure).

In this window, you can define the necessary parameters to determine the shrinkage strain and specify the following settings:

• Considered concrete age
• Type of cement
• Concrete age at beginning of shrinkage
• Relative air humidity
• Alternative application of drying shrinkage and/or autogenous shrinkage

Furthermore, you can define a total shrinkage strain εcs that was determined elsewhere as user‑defined shrinkage. You can also select the surfaces to which this will be applied.

Alternative to the input in RF‑CONCRETE Surfaces, the shrinkage strain can also be entered in a separate load case as surface load (load type “Axial strain”), as was already possible in RFEM 4.