抄録
An elastic-plastic analysis was performed on the hysteretic behavior of a steel braced frame subjected to repeated horizontal load. Each member was assumed to be composed of three elastic-plastic springs and two straight segments. The relative rotation of the spring was dependent on the moment-curvature relationship of individual member. The governing equations included the second order terms of the large deflection of brace members, and the optimum increment of load and deformation parameters were obtained by solving the second order simultaneous equations. The computed results on the K-type braced frame reasonably agreed with the experimental results, and derived following conclusions. 1) The beam in K-type braced frame is subjected to the lateral force which is the sum of the vertical components of the axial forces of braces. The hysteretic characteristics of the system much depends on the elastic-plastic behavior of the beam, because the brace can not hold its full strength when the beam yields in bending by the lateral force caused by braces. 2) If the weak beam and stubby braces are combined, the large plastic deformation of the beam causes the severe deterioration of the hysteresis loop. 3) The lateral registance of the beam can be estimated by Q_<g0>=2M_<g0>/l_g, where M_<g0> and l_g is the full plastic moment and the clear span of the beam, respectively.
