Rectangular section second moment of area
= Rectangular section second moment of area
{title2=$I=ab^3/12$}
For a rectangular cross-section of horizontal width $a$ and vertical thickness $b$, the <second moment of area> about its horizontal <centroid> axis is $I=a\int_{-b/2}^{b/2}z^2\,dz=ab^3/12$. Thus increasing vertical thickness is especially effective at reducing the <curvature> caused by a given <bending moment>.