抄録
This paper is concerned with the dynamic analysis of core-wall type buildings, which have a box-shape wall extending over the height of the building as shown in Fig. 1. To investigate the dynamic characteristics under the effect of earthquake ground motions, it is assumed that; (1) the masses and the stiffnesses are uniformly distributed over the height of the building, (2) all the memders of the structure are distorted within an elastic range, (3) the open frames vibrate as a shear beam type structure, and the core walls behave as a cantilever standing on the foundation and are subjected to restraint action from theadjacent beams, and (4) there is no foundation rotation. With these assumptions the system can be analyzed as a combination of a shear beam and a cantilever. The fourth order partial differential equation is then derived as the equation of motion when the system is subjected to earthquake grond motions, and its solution is given by modal expression. Numerical study is made on the mode shapes and their corresponding stress distribution in several cases both for fixed and pinned conditions at the wall base. The sesults indicate that; (1) the dynamic characteristics of ordinary type core-wall buildings is close to that of the shear beam rather than the cantilever, and (2) the effect of fixation at the wall base on the modal stresses is limited to lower stories. Finally, earthquake responses of six ideal buildings are obtained using an analog computer, and the results are compaired with so-called "root mean square" values and the maximum values when the first mode only is considered. From this comparison it is concluded that; (1) "root mean square" values are always very close to the exact maximum values except a very few cases, and (2) in most cases the first mode maxima are neary alequal to the exact maxima. The exceptional case is seen in one of the sample buildings, for which the maximum values of the first and second modes are comparable.
