Shrinkage strains occur over time and a number of models are available to predict the development of shrinkage as a function of time. The following creep models are implemented in RAM Concept and can be selected for use in the Load History / ECR tab of the Calc Options dialog: ACI 209R-92 (ECR values), ACI209.2 – GL 2000, AS 3600-2018, and Eurocode 2-2004. See Creep and Shrinkage Models for a brief description of each model.

Shrinkage models generally include an adjustment factor for a volume-to-surface ratio or an effective cross section thickness. The Exposure property in the Load History / ECR tab of the Calc Options dialog defines the element surfaces that are exposed and used to determine the exposed perimeter for that adjustment. When "Top and Bottom" is selected, both top and bottom surfaces of the element are assumed exposed. When "Top Only" or "Bottom Only" is selected, only the top or bottom surface of the element is assumed exposed, respectively.