ABSTRACT
The geometrical properties of sections are of great importance in a number of different branches of engineering, including stress analysis. Typical beam cross-sections for symmetrical sections include circular, rectangular, triangular, I and T sections. The strength of a structure is dependent on the material properties of the structure and also on its geometrical properties. Since the invention of steel, the strength of a beam can be increased by the shape of its cross-section, in addition to the size of its cross-section. This has been achieved by the introduction of flanges in its cross-section. This chapter shows to: define a centroid, centroidal axes, calculate the second moment of area of a section, understand and use the parallel axis theorem, understand and use the perpendicular axis theorem. It also shows to: calculate the second moment of area using numerical integration, using the Naval architects' method and Ross's method, use a computer program to determine centroids and second moments of area.
