ABSTRACT
This chapter describes the second-order inelastic analysis on the basis of the plastic-zone theory for inplane beam-columns and portal frames. It is recognized that the analysis based on the plastic-zone theory is most accurate. It can most realistically reflect the behaviors and the ultimate load-carrying capacity of the members or structures. The chapter presents three programs: Program BCIN, Program FRAMP, and Program FRAMH. In these three programs, the members of beam and columns are divided into a number of segments, and the sections of these members are further divided into a number of strip elements parallel to the bending axis. The elastic range and resultant force in each strip can be obtained by simple mathematical procedures: the stiffness of the section is obtained by integrating the stiffness of the elastic range area of each strip, and the internal axial force and moment of the section are also obtained by integrating the resultant force of each strip.
