Plastic Analysis2024-05-08T10:38:06+02:00
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Plastic Analysis

Plastic Analysis is a material non-linearity module in FEM-Design that expands the capability of structure analysis and enables accurate and realistic structural analysis without compromise for every user and everyday design projects. It empowers material savings and safety for steel and concrete structures.

For concrete structures, the module uses complex and realistic non-linear hardening and cracked concrete models, including all rebars. For plated steel structures, it enables ultimate non-linear plastic capacity calculations for steel and allows steel yield when the yield limit is reached. Steel bars (beams and columns) get a plastic material model.

RC wall element connections, timber connections, weld connections, and any connections on structure material non-linearity allow plastic behaviour when the capacity is reached. For foundations, this can be used to model the capacity of sub-soil and get accurate foundation subsoil reactions.

Plastic Analysis

Key Advantages of Plastic Analysis

Reduced Costs

More accurate analysis takes into account full capacity of wall elements and plates and correct optimal load distribution. Cost saving can be up to 30%.

Increased Safety

More accurate analysis models to acquire real behaviour of structure and elements. Load paths are correct and realistic. Also, ultimate strains and realistic crushing models are done by analysis model so rotational capacities and displacement capacities are checked unlike simple hand calculation models.


Single model can be used for internal force analysis and rebar and concrete design. One solution for details and analysis.

Increased Safety and Material Savings in Concrete Analysis

Material non-linearity for concrete can be used to perform the total analysis and design of plane-stress structures like walls, shear walls, deep beams with openings and deep foundations. A model can be applied to any slab structure to model non-linear behaviour with cracking and rebar yield. The internal force re-distribution can model behaviour with real rebars. Also, 3D structures like shafts and lateral load-resisting wall systems are good applications for the module. The model includes the ultimate strain check of rebars and concrete, rotational capacities of plates and strain capacities of walls, which can be checked realistically with a 3D model.

Watch the Plastic Analysis for Concrete Shells Overview Video

wall 1
plate 1
deep beam 1
wall line
shaft 1
wall 1
plate 1
deep beam 1
wall line
shaft 1

Tested and Verified Material Model

The concrete material non-linearity includes all possible compression side material non-linearities: stress-strain modelled with parabola and bi-axial behaviour, which approximates Kupfer test data. Tension side behaviour includes multiple tension stiffening models to describe the realistic behaviour of reinforced concrete under tension when cracking occurs with rotating crack theory. Non-linearity also includes complex interaction models, which will take into account the reduction of compressive strength when concrete cracks and plate thickness direction shear stiffness reduction due to cracking.

All these models can be adjusted by the user: for example, the user can exclude the tension capacity of concrete or use the very brittle behaviour of concrete. This means models can be adjusted for ULS ultimate safe-side capacity analysis in extreme cases, but also service limits state performance analysis of any concrete structure with very realistic stiffness distributions.

All rebars, reinforcement meshes and single-addition rebars with anchoring lengths are included in the model. Both concrete and reinforcement have failure models. Concrete failure models can be adjusted, and they take into account the bi-axial nature of the concrete’s ultimate failure in compression.

Tested and Verified Material Model (2)

Bi-axial bending of plate with different rebar ratios in x- and y-directions and different top and bottom rebars. FEM-Design model compared to test data of real plate and also other numerical models.

Analysis Does Not Stop to Yield Limit in Steel Analysis

Material non-linearity introduces a perfectly plastic material model for plated steel structures, beams and columns. The model uses the Von Mises failure theory to take into account the bi-axiality of stresses. The model also includes a failure model for plates, so the ultimate strain can be automatically checked, and complex failure modes can be analysed.

Material non-linearity makes plated structure analysis realistic. Effects of material yielding can be taken into account. Real ultimate capacity can be analysed thanks to the included bi-axial failure model. Also, rotational capacities or tension strain capacities of details can be checked. For beam models, plastic module enables analysis of cross section yielding.

Watch the Plastic Analysis Overview Video

Steel detail 1
Steel rotation 1
Beam Plastic

Plastic in Global Structure Analysis

Material non-linearity also helps in the global analysis of structures. All connections, including RC elements, timber elements and beam connections, can be calculated with plastic capacity.

This means the realistic behaviour after reaching the capacity of connections and the full capacity of global structure can be analysed. All this translates to material savings and correct behaviour. Plasticity of surface connections can be used to model the failure of sub-soil after the capacity is reached.

analysis F
found 1

Benefits of Plastic Analysis

  • Analyse and design concrete elements and structures with realistic and adjustable material models with real exact rebars

  • Save material and reduce carbon footprint up to 30 % in concrete structures with more accurate analysis and better full capacity utilisation

  • Increase the safety of concrete structures with more accurate models. Ensure sufficient rotation capacity and ultimate strain and get more realistic stress distribution between load-bearing elements, and take into account the effect of rebars on load distribution

  • Analyse steel with plastic capacity and better understand the steel structure behaviour when plastic capacity is utilised. Check the ultimate strain to increase the safety in steel structure analysis

  • Get the correct global behaviour, utilise connections better with connections plastic model, and save material

Why wait? Download an automated 2 x week free trial of FEM-Design and get started today!

Calculations performed according to:

  • Euro Code
  • Belgian National Annex
  • British National Annex
  • Danish National Annex
  • Dutch National Annex
  • Estonian National Annex
  • Finnish National Annex
  • German National Annex
  • Hungarian National Annex
  • Latvian National Annex
  • Norwegian National Annex
  • Polish National Annex
  • Romanian National Annex
  • Spanish National Annex
  • Swedish National Annex
  • Turkish Seismic Code

Languages supported:

  • English
  • Finnish
  • French
  • Dutch
  • Hungarian
  • Polish

FEM-Design Wiki

Full details on the Plastic Analysis module and the theory can be found on the FEM-Design Wiki by clicking here.

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