Concentrated Plasticity

An in-text example, shown in Figure 10.5

W12x65, E=29000 ksi, F_y=50 ksi, A=19.1 inch², Z=96.8 inch³, I=533 inch⁴

N_p=F_yA, M_p=F_yZ

Yield surface: \(n^2+m^2+3.5n^2m^2=1\)

Not available in OpenSees, but we can use Elliptical section model with yield surface \(n^2+m^2=1\).

First plastic hinge at P=260 kip

Second plastic hinge at P=331 kip