FEM-Design Plate Module

In Brief
 
FEM-Design Plate offers a powerful and easy way to design concrete slab systems according to actual concrete behaviour. Features of the module include powerful cracked section analysis, punching calculations, shrinkage effects, and the ability to apply and analyse user defined reinforcement.

The basic outline model can be generated by the programs own CAD tools or imported via DXF/DWG or model based IFC links. The structural elements are defined with easy to use tools for plate regions, beams, column and wall supports. An inbuilt structure wizard is also available. This can be used to generate regular models including all structural elements and the applied loading.

Model built from a DWG drawing.
The programs powerful mesh generator automatically produces a mesh adjusted to the current geometry, support and loading conditions. Designs can then be carried out according to EC2 and 9 other national codes with features such as cracked section analysis, shrinkage behaviour and punching shear calculations all taken into account.
There are several easy-to-use tools for defining the “accurate” static model: absolute and relative coordinates, user-coordinate system, drawing and editing tools, region operations, special point editors, object snap tools, layer system, etc. There is no geometrical limit and plates can be created with any shape and thickness values, beams/columns with any section and walls with variable thicknesses, walls with variable thickness, etc.

Further special features are also available, such as designs of slabs with varying thickness, modelling of orthotropic material behaviour and checking of plate corners for uplift above supports.
 
Växjö Library
The library is a three-storey building with a diameter of 38 m. The figure shows the required and applied reinforcement & punching checking of slab above columns.  
Structural design: Sycon Teknikkonsult AB

Powerful reinforcement design
 
An initial calculation provides required top and bottom bending reinforcement across the whole slab, together with the corresponding punching shear capacities, deflection results and crack widths. On the basis of the above results the user can define the desired (applied) reinforcement in any shape and direction.

The Växjö Library FEM-Design model images (right) show an example of the required reinforcement results. Areas in red highlight that not enough top reinforcement in the X direction has been provided.

The RC design module also suggests additional reinforcement required after taking punching shear into account. In addition to the numerical output, the columns are displayed in different colours depending on the shear capacity with or without any additional shear reinforcement (e.g. green columns indicate that the shear capacity is OK with existing reinforcement, and red means that the shear capacity is too small even with additional shear reinforcement).
 
Cracked-section analysis
 
Deflections may be calculated using cracked-section analysis applied for serviceability load combinations and user-defined reinforcement. As well as deflection results, crack width and crack direction (crack lines) results can also be requested.
As an example, FEM-Design Plate module was used in the design of The Chimes Shopping Centre, Uxbridge, because of the great flexibility offered in placing future openings in the slab. The program also provided substantial savings in the reinforcement design compared with conventional methods.
 
Peak smoothing procedure
12 storey building in Linköping, Sweden with Offices, Laboratory for Biotechnology and Shopping Centre. The total gross floor area is 9000 m2. The staircases of posttensioned concrete are used for stabilizing the building. The construction work started in April 2002 and was finished in December 2003. Structural Engineer: CSE Civil & Structural Engineering Projekt AB

 
FEM-Design gives an automatic solution for addressing the singularity problem (peaks) of internal and design force results above supports. Automatic peak smoothing regions can be applied by the program in user specified locations (e.g. over columns, at beam and wall end points, etc.). These regions provide more realistic results and are calculated based on the column, beam or wall size and the thickness of the plate.
 
Geometry Import/Export
 
Two types of geometry import can be carried out in FEM-Design: DWG/DXF drawing and model-based IFC.
 
Design of ribbed slabs
 
In FEM-Design Plate, beams under the slab (i.e. ribbed slabs) can be modelled for static analysis including internal forces and displacement. The design results for design forces, areas of required reinforcement and crack widths can all be displayed in various forms.
 
4 simple steps to concrete design  

  1. Run the concrete design and analysis to obtain the required reinforcement and punching results.
  2. Define (applied) top/bottom reinforcement in the slab taking into consideration the previous design results.
  3. Run a check on the applied reinforcement combined with cracked-section analysis.
  4. Analyse the deflection, crack width and missing reinforcement results and increase the reinforcement if needed. Repeat the checking process until the optimal reinforcement design is achieved.