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Shells: Maps

This tab is used to visualise internal forces on shells as maps. The sign convention is the usual right hand system as shown.

results-shells results-shells

1. Load combination

The name of the load combination to display results for.

2. Result category and type

Various categories of shell results can be visualised. The Results category field is used to select the category, while the Results type is used to select the type of result under each category. The various categories and their types are described below.

3. Membrane forces

The sign convention for membrane forces is shown below:

results-shells-membrane

The membrane forces are as follows:

  • Nxx: Membrane force per unit length in the local x-direction on a face perpendicular to the local x-axis. It causes normal stress in the local x-axis direction.
  • Nyy: Membrane force per unit length in the local y-direction on a face perpendicular to the local y-axis. It causes normal stress in the local y-axis direction.
  • Nxy: Membrane force per unit length in the local y-direction on a face perpendicular to the local x-axis. It causes shear stress in the local x-axis direction. Nxy and Nyx are equivalent in magnitude.

4. Shear forces

The sign convention for shear forces is shown below:

results-shells-shear

The shear forces are as follows:

  • Vxz: Shear force per unit length in the local z-direction on a face perpendicular to the local x-axis.
  • Vyz: Shear force per unit length in the local z-direction on a face perpendicular to the local y-axis.

5. Bending moments

The sign convention for bending moments is shown below:

results-frames

The bending moments are as follows:

  • Mxx: Bending moment per unit length about the local y-axis on a face perpendicular to the local x-axis. It causes normal stress in the local x-axis direction.
  • Myy: Bending moment per unit length about the local x-axis on a face perpendicular to the local y-axis. It causes stress in the local y-axis direction.
  • Mxy: Bending moment per unit length about the local x-axis on a face perpendicular to the local x-axis. Mxy and Myx are equivalent in magnitude.

6. Design bending moments

Design bending moments calculated using the Wood-Armer method. These are the moments you are supposed to use when performing reinforced concrete design.

  • Mx+: Design bending moment per unit length about the local y-axis. Controls the top reinforcement parallel to the local x-axis.
  • My+: Design bending moment per unit length about the local x-axis. Controls the top reinforcement parallel to the local y-axis.
  • Mx-: Design bending moment per unit length about the local y-axis. Controls the bottom reinforcement parallel to the local x-axis.
  • My-: Design bending moment per unit length about the local x-axis. Controls the bottom reinforcement parallel to the local y-axis.

Reference:

Wood, R. H., et al. "The Theory of the Strip Method for Design of Slabs.(Includes Appendix)." Proceedings of the Institution of Civil Engineers 41.2 (1968): 285-311.

7. Membrane stresses

The membrane stress or angle of principal membrane stress. The sign convention is as described above for Membrane forces.

  • Sxx: Membrane stress in the local x-direction on a face perpendicular to the local x-axis.
  • Syy: Membrane stress in the local y-direction on a face perpendicular to the local y-axis.
  • Sxy: Membrane stress in the local y-direction on a face perpendicular to the local x-axis. Sxy and Syx are equivalent in magnitude.
  • Major: Major principal membrane stress.
  • Minor: Minor principal membrane stress.
  • Angle: Angle of principal membrane stress.

8. Shear stresses

The shear stress in the shell. The sign convention is as described above for Shear forces.

  • Sxz: Shear stress in the local z-direction on a face perpendicular to the local x-axis.
  • Syz: Shear stress in the local z-direction on a face perpendicular to the local y-axis.

9. Bending stresses

The bending stress or angle of principal bending stress (in degrees). The sign convention is as described above for Bending moments.

  • Sxx: Bending stress in the local x-direction on a face perpendicular to the local x-axis.
  • Syy: Bending stress in the local y-direction on a face perpendicular to the local y-axis.
  • Sxy: Bending stress in the local y-direction on a face perpendicular to the local x-axis. Sxy and Syx are equivalent in magnitude.
  • Major: Major principal bending stress.
  • Minor: Minor principal bending stress.
  • Angle: Angle of principal bending stress.

10. Total stresses

The total stress or angle of principal total stress (in degrees). The sign convention is as described above for Membrane forces and Bending moments.

  • Sxx: Total stress in the local x-direction on a face perpendicular to the local x-axis.
  • Syy: Total stress in the local y-direction on a face perpendicular to the local y-axis.
  • Sxy: Total stress in the local y-direction on a face perpendicular to the local x-axis. Sxy and Syx are equivalent in magnitude.
  • Major: Major principal total stress.
  • Minor: Minor principal total stress.
  • Angle: Angle of principal total stress.
  • Von Mises: Two-dimensional Von Mises equivalent stress for plane stress conditions.

11. Layer (-0.5 to 0.5)

The layer at which the stress is required, ranging from -0.5 (bottom surface) to 0.5 (top surface)

12. Show result values

Whether to display results values on the maps.

13. Values text color

The text color of the results values.

14. Number of contours

The number of divisions to use in the color map.

15. Hide mesh

Whether to hide the mesh when the result maps are drawn.

16. Results smoothing

Due to numerical approximation, results from one finite element may not exactly match those from an adjacent element. Some averaging may therefore be required to produce smoother and more representative results. You can choose from the following smoothing options:

  • None: No smoothing is performed. Raw element results are displayed.
  • Continuous in each shell: Result values along shared edges are averaged between adjacent finite elements belonging to the same shell.
  • Continuous in model: Result values along shared edges are averaged between adjacent finite elements throughout the model, even when they belong to different shells, provided they are connected. Use this option with care. Different shells may have different local axis orientations, meaning the results may not represent the same physical directions and may therefore not be suitable for averaging.

17. Apply button

Plots the selected results type. If some elements are selected, results are displayed only for those elements.

18. Clear button

Clears all result graphics from the model view.

19. Close button

Closes the window and clears all result graphics.