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.
Related Articles
Important New Features & Enhancements of ProtaStructure 2025
At Prota, we've been shaping the future of structural BIM software for over 40 years. Our commitment to practical solutions and innovative design tools remains unmatched, and ProtaStructure 2025 is no exception. This latest release pushes the ...Working with Flat Slabs
Flat Slab Guidelines The modelling, analysis and design of flat slab is described in detail here : For ProtaStructure 2022/ ProtaStructure 2024: Flat Slab Modelling, Analysis and Design For Flat Slab and Raft Design with Slab Patch Panel: Flat Slab ...Working with Slabs
Defining a New Slab Before inserting a Slab member its reference axes should be defined. To define a new Slab member: Display the storey level in the drawing area which will contain the slab. Press the “Slab” button located in "Modelling" ribbon. ...Working with Slab/Column Edge
Curved, Circle & Multi-segment Sketch Line Creating irregular shaped slabs and columns has never been easier with "Slab/Column Edge" tool. The "Slab/Column Edge" is accessible from "Modelling" ribbon. Slab/Column Edge (Polyline) To define ...Analysis and Design of Slab Overview
Design settings of slabs are explained in detail in the following sections. Slab Analysis and Design Procedure Analytical Strip (Moment Coefficient Method) Finite Element FE Strip Ribbed Slab Modelling & Design Procedure Column Punching Check Column ...