Comparing second order moments calculated with analytical methods with those obtained from FEM calculation in Advance Design modules (idealized end restraints + only top/bottom torsors)

Type: Square

Section: 50 x 50 cm

Height: 4.00 m

End restraints:

Loads for General method:

Loads for FEM calculation:

*Note:*
When
FEM calculation is performed, the loads defined in the Internal Efforts
dialog are considered external loads.

**Second-order moments
and provided reinforcement**

General method:

FEM calculation:

**Conclusions**

The required reinforcement area calculated using the general method is 8.78 cm

^{2}and the required reinforcement area calculated using the second-order method is 5.00 cm^{2}.The required reinforcement area obtained from the general method calculation is greater than the required reinforcement area resulting from the second-order method. This can be explained by the fact that during FEM analysis the real stiffness of the column section is considered (also including additional stiffness brought by the reinforcement).

In a final step, the column section is verified using interaction curves. As can be noticed there are red lines in the tables above which means that there are work ratios greater than 100%. This is caused by the fact that after the real reinforcement is generated, to cover the required area, the program performs only a verification of the section using interaction curves without automatically redimensioning the real reinforcement; this action must be performed manually by the user (increasing the bar number or the diameter of the bars).