Moment of Inertia of Some Composite Sections

The composite section in Figure 11.20 can be divided into three parts—triangular part of area A₁, rectangular part of area A₂, and semicircular part of area A₃. The individual centroid for each section is shown in Figure 11.20 as C₁, C₂, and C₃. The centroid of entire section is located at C. Consider the moment of inertia of the sections 1, 2, and 3 about the axes parallel to XX and passing through their individual centroid are I_C1, I_C2, and I_C3, respectively. The moment of inertia of the entire composite section about the axis XX passing through the centroid C can be given as

Figure 11.20 Moment of Inertia of a Composite Section