THE LIMIT LOADS OF STEEL SEMIRIGID FRAMES ANALYZED WITH DIFFERENT METHODS

A simple and practical model is proposed for the analysis of the secon d-order inelastic behavior of semi-rigid frames. The method is based o n a three-parameter model of the rotational stiffness of the connectio ns and a phenomenological model for representing the degradation in th e tangent stiffness of beam-column members due to distributed yielding . It is found that the conventional simple plastic hinge method tends to overestimate the limit load of semi-rigid frames, no matter that th e beam-to-column connections are stiff or soft when the axial loads in columns are large. The load deflection response predicted by the prop osed method is smooth and close to that obtained by more accurate inel astic analysis methods and experimental results.