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.
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.
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.