Abstract
This paper presents the earthquake response analysis of steel portal frames by using the substructure pseudodynamic testing method. The numerical model of frames to be simulated is divided into the web plates in the middle of beam for testing substructure and the two elasto-plastic rotational springs for computational structural elements. The equation of motion and fundamental equations are explained to employ the α-OS method as an implicit time-stepping algorithm. The analytical results demonstrate the non-linear response of frames with the shear collapse in beam. This is affected by the remarkable change in shearing resistance force of web plates due to shearing buckling and diagonal tension field. When the initial yielding occurs at web plates in beam, it is observed how the plastic deformation and corresponding hysteretic energy at the bottom of column vary due to the shearing collapse in beam. The damage mechanism of frames is discussed and outlined by focusing on the fact that the shearing collapse of web plates in beam could make the plastic deformation at the column base part small.
