Factor de forma: f = M P l M C = w P l w e l {\displaystyle f={\frac {M_{Pl}}{M_{C}}}={\frac {w_{Pl}}{w_{el}}}}
Portanto:
M C = w e l f y {\displaystyle M_{C}=w_{el}f_{y}} e M P l = w P l f y {\displaystyle M_{Pl}=w_{Pl}f_{y}}
χ P l ′ = f χ C {\displaystyle \chi '_{Pl}=f\chi _{C}}
M P l = f M C {\displaystyle M_{Pl}=fM_{C}}
Cálculo do momento plástico em secção não-simétrica:
C = − ∫ A C f y d A = − f y A T {\displaystyle C=-\int \limits _{A_{C}}f_{y}dA=-f_{y}A_{T}}
T = − ∫ A T f y d A = − f y A T {\displaystyle T=-\int \limits _{A_{T}}f_{y}dA=-f_{y}A_{T}}
Então:
M P l = ( S C + S T ) f y = C y C + T y T = ( A C y C + A T y T ) f y {\displaystyle {\begin{aligned}M_{Pl}&=\left(S_{C}+S_{T}\right)f_{y}\\&=Cy_{C}+Ty_{T}\\&=\left(A_{C}y_{C}+A_{T}y_{T}\right)f_{y}\\\end{aligned}}}
e 
