ProtaStructure : One-Way Slabs with Orthotropic Shell Elements

One-Way Slabs with Orthotropic Shell Elements

Normally, a regular isotropic slab will exhibit a two-way behavior when analyzed with finite elements. This is usually sufficient for cast-in-place RC slabs.

However, when it comes to one-way prefabricated, pretensioned or hollow core slabs, the one-way behavior must be accurately reflected to the analytical model. 

In finite element modeling of one-way slabs, the Orthotropic Shell Element is used which has a significantly lower Modulus of Elasticity, Shear Modulus and Poisson’s Ratio in the secondary direction. 

ProtaStructure will automatically adjust the analytical properties when the slab is specified as a one-way slab.

Notes
This function is available starting from ProtaStructure 2025.









In addition to orthotropic material properties, End Releases can be applied to one-way slabs.

This will be useful to model scenarios where the slab is sitting on the supports without any moment connection or non-load transferring edges are not supported in z direction.




Moment Release at Supported Edges

The load transferring edges of the one-way slabs will be hinged, i.e., they will not transfer any bending moments to the supports.


Disconnect Unsupported Edges

The non-load transferring edges will be disconnected from the neighboring slabs and supports, allowing them to deform independently.


Alert
The moment release and disconnection are achieved by duplicating the nodes and utilizing equal constraints in relevant degrees of freedom. This approach works best in slabs whose edges are parallel to global X and Y coordinate axes.

To model a hollow core slab or any other slab system with these features, user are expected to enter the correct thickness and material properties. ProtaStructure will not automatically calculate those properties.

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