Field note / structural geometry
Build the section from overlapping rectangles.
The L-section can be represented by a full vertical leg plus a horizontal leg, with their corner overlap subtracted once. That keeps the area and centroid calculation easy to audit.
Every extreme fibre has a direction.
Ix is measured about the horizontal centroidal axis and Iy about the vertical centroidal axis. The top, bottom, left, and right section moduli use different distances from the centroid.
What the calculator reports
- Area A and centroid x̄, ȳ from the left and top outer faces.
- Ix and Iy using the composite-area and parallel-axis method.
- Ztop, Zbottom, Zleft, Zright for the four outer fibres.
- rx and ry as the centroidal radii of gyration.
What still needs a design check
Unsymmetric bending, principal-axis rotation, product of inertia, local buckling, connections, holes, welds, material resistance, and code-specific checks remain outside this gross-property screen.