Creep and shrinkage parameters on a plate element


I am working on a network tied arch structure where the model is utilizing plate elements for the deck.  The structure has prestressed girders as floorbeams in the direction transverse to the structure and post tensioned tie beams longitudinally, therefore the plate deck elements will be experiencing creep and shrinkage in two directions.  The notational thickness under CEB-FIP considers the perimeter around the plane perpendicular to the expected effect.  In the case of prestressing/post-tensioning in two directions, that perimeter and area will be different and therefore the creep and shrinkage effects will be different.  The Midas input appears to only allow for a single notational thickness to be entered and therefore the effect is applied equally in both directions.  

How can I accurately model different C&S effects in each direction in Midas?



So far, we haven't encountered a practical solution to this problem.  If there is a feasible approach or manual calculation for this, kindly share it with us and we will definitely incorporate it.
Generally, what engineers do in this situation is a bit of approximation and the notional size for a deck is considered as its thickness, the justification for which is as below.

A sample calculation for a deck that 200ft long and 2o ft wide with a thickness of 6 inches could be referred to below.

So, this justification holds true for both longitudinal as well as transverse direction.  Kindly let us know if further assistance would be required.
Creation date: 2/26/2020 4:35 AM      Updated: 2/26/2020 3:08 PM
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