Optimal Performance- Based Seismic Design - Structural Seismic Design Optimization and Earthquake Engineering - page 192

Figure 5. A trilinear moment curvature relation

penetration coefficients, and L is the free length
of the element. Having α A and α B together with
EI A and EI B , facilitates obtaining the flexibility
curve of a member and its corresponding defor-
mation, etc.

and its flexural deformation. Accordingly Figure
6b can be considered for the flexibility distribution
in the RC elements. In Figure 6b, EI A and EI B
are the flexural stiffness of the section at end 'A'
and end 'B', respectively, and EI 0 is the initial
stiffness of the element; α A and α B are the yield

Figure 6. (a) Curvature distribution along a RC element, (b) flexibility assumption along a RC element