The main function of the Section Definition module is to indicate the geometric properties of the defined solid section. For composite sections, only the weighted properties are calculated (marked with *) using the following formula:
where:
i - i-th material of the composite section
b - base material of the composite section.
General results include the following values, which are given as geometric and weighted values: area, center of gravity coordinates, dimensions, and base material parameters (Young's modulus, density, weight per unit). You can select to perform additional calculations (select the appropriate option and click Calculate).
- Torsional constant (Ix moment of inertia)
- Shear area (Ay, Az)
- Shear rigidity factors (Wy, Wz)
- Plastic section moduli (Wply, Wplz)
Plastic section moduli about the principal - central section axes are calculated from the following formulas:
A bending moment with respect to the y or z axis, which causes complete plastification of a section, is a product of a value of the plastic section modulus about the y or z axis and a yield point value. Surfaces of equal areas that result from division by means of the neutral line parallel to the y axis are represented by 
. Surfaces of equal areas that result from division by means of the neutral line parallel to the z axis are represented by 
.
Results of additional calculations are displayed on the Principal System tab of the Results dialog.