public
Section modulus of square hollow section (RHS)
External height
$$ H = 100 \:
mm $$
Internal height
$$ h = 90 \:
mm $$
External width
$$ B = 100 \:
mm $$
Internal width
$$ b = 90 \:
mm $$
Section modulus
$$ W_{y_{RHS}} = {{\left({ B \cdot H ^ 3 - b \cdot h ^ 3 }\right) \over \left({ 6 \cdot H }\right)}} \:, mm^3 $$