Abstract
The aseismic capacity of the steel structures which are composed of rigid frames with and without braces is presented as a figure illustrated in the spase whose coordinates are acceleration response factor, natural period and damping coefficient. This figure shows that it is reasonable that "strength" and "hysteretic damping capacity" are taken to be the earthquake-resisting factor of frames with and without braces respectively. As for the frames without braces, the hysteretic damping capacity is estimated analytically based upon the flexural deformation mechanisms and fatigue characteristics of the structural members and sections composed of plate elements. By applying the hysteretic damping capacity to the steady-state resonacce of the structures subjected to forced sinusoidal ground vibrations, a concrete estimation procedure on the aseismic capacity of rigid steel frames without braces is proposed.
