Abstract
When a multi-storey frame is composed of a rigid frame intercorporated with a canti-lever type of shear walls, the flexural deformation of walls often predominates over the shear deformation in the upper floors. Under such a circumstance, a considerable amount of damage concentration can take place on the upper part of the rigid frame when the frame is subjected to strong earthquakes. This paper deals with the damage distribution in such a structure. As a first step, a structural model shown in Fig. 1 is taken up, which consists of rigid frames symmetrically disposed on left- and right-hand sides and a central shear wall connected to the rigid frames with elastic boundary beams on each floor level. Beams in rigid frames are assumed to be rigid. Columns in the rigid frames can behave inelastically with the elastic-perfectly plastic restoring force characteristics. Beams in the shear wall is also assumed to be rigid and columns in the shear wall are pin-connected at both ends and remain elastic. The shear wall is equipped with the central core which behaves as a column with shear resistance, the restoring force characterictics of which is assumed to be elastic-perfectly plastic. Eventually, the shear wall deforms elastically under bending and can behave inelastically under shear forces. The apparent yield deformation of the shear wall is defined to be the storey displacement at the onset of the yielding of the central core. The apparent yield deformation becomes larger as the level of storey goes up. On the other hand, the yield deformation of each storey of the rigid frame show no conspicuous change. Therefore, this model is considered to be a structure which is copmposed of different elements in yield deformations. When the boundary beams are rigid, the flexural deformation of the shear wall is suppressed and the model becomes a shear type structure consisting of two elements with different yield deformation. First, the damage distribution law which can apply to shear type structure is derived in terms of the ratio of the yield deformations of two elements. Next, the damage distribution law is generallized by introducing the apparent yield deformation of the shear wall and the adequacy of the generalization is assured by comparing the prediction with the result of the response analyses for the model with elastic boundary beams.
