Inelastic Section Response by Tangent Stiffness

A review of inelastic analysis of a cross section is made. Given the history of deformation, the history of axial force and moment may be obtained. Also, given the history of moment and axial force the history of deformation may be obtained. The tangent stiffness method is modified to avoid convergence difficulties due to large inelastic unloading. Stress-strain curves considered are generally nonlinear but symmetric, exhibiting hysteresis and the Bauschinger effect. The solution is checked against others. The method has been included in a discrete element frame analysis program and used to predict the behavior of a brace member for which experimental results are available.