How to do concrete design

To assess a structure (whether it is sufficiant or not), the following steps must be followed in sequence:

• Schematising the construction
• Determining the internal forces and moments (= global analysis, elastic analysis)
• Checking the cross-sections (= design):
  • Strength
  • Stability 
  • Stiffness

The explanation below covers the design of concrete.

In Diamonds

1. Generate at least the combinations ULS FC, SLS RC and SLS QP .
2. Determine which analysis type you’re going to use. Based on the analysis type you’ve chosen:
   • (un)check the buckling verification;
   • enter the correct value for the accidental eccentricity e_a;
   • if relevant, set the buckling lengths .
3. Calculate the internal forces F9 or .
4. Select the correct concrete standard using the menu Analysis > Concrete standard.
5. Click on F2 or  to calculate the reinforcement. The calculated reinforcement will take the strength and stability requirements into account.
   Related articles:
   • Error: Combinations are missing
   • Error: The cross section of some elements is insufficient
   • Displaying reinforcement results in bars and surfaces.
   • How to show the basic intermediary reinforcement results for bars
   • How to show the advanced intermediary reinforcement results for bars
6. (Optionally) Define practical reinforcement.
7. Diamonds sets the creep factor for deformations equal to 2 by default. Verify if this value applies to your model. If not, make the necessary adjustments in the material library and assign the new material to the relevant elements.
8. Redo the elastic analysis (F9 or ) but take cracking into account.
   Some cross-sections will be more cracked than others. This will lead to a redistribution of the internal forces. Which in turn can lead to a additional cracking.
   
   • Check the option “Compute deformations after creep“.
   • If the model contains walls or plates loaded with axial force, also check the option “Extend cracking theory to axial forces”.
9. Click on F2 or  to calculate the reinforcement.
10. Repeat steps 8-9 until the results (for example the internal forces) converge. This is usually already after 1-2 recalculations.
11. Manually verify the shear force in the plate. Diamonds does not verify if V_Ed < V_Rd.c.
12. Manually verify the punching shear in places with concentrated loads.
13. The cracked deformation will already be available, but if you want the cracking widths as well, click on .
    
    • Check the option “Compute deformations after creep“.
    • If the model contains walls or plates loaded with axial force, also check the option “Extend cracking theory to axial forces”.
14. Verify the cracking widths w_k (see EN 1992-1-1 Table 7.1N)!
15. Verify the cracked deformation (horizontal and vertical)!
16. (Optionally) Calculate the cracked deformation in time .
    This calculation is often necessary when the additional deflection (e.g. due to the installation of walls) must be limited.

FAQ