原田 幸博

The effect of ground motion on a building is taken as energy input, and is absorbed as structural damage during strong earthquakes. The relation between yield strength distribution and damage distribution has already been determined experimentally by numerical analysis. The purpose of the present study is to contribute an analytical examination of the damage distribution law of the multi-mass shear system. By considering the resonance response of stiff-perfectly plastic multi-mass shear system, the author develops a theoretical damage distribution law, and shows that it is in accord with damage distribution laws previously proposed.

Hitherto, the overturning of rigid bodies under earthquakes have been dealt with in terms of the maximum ground accelaration and the maximum ground velocity. However, the adequate estimate for all shapes and sizes of rigid bodies has not been established yet. In this paper, the energy approach is applied to the overturning problem. By introducing the equivalent period of vibration, the energy inputs to rigid bodies are estimated based on the energy spectrum. The possibility of overturning is judged by equating the energy input to the potential energy of rigid bodies on the brim of overturning.

The method for estimating the ultimate strength of outer columns in multi-story frame under earth-quakes is not established yet. It yields an underestimate of the buckling strength of outer column to take the column length for buckling length as is applied expediently, because outer column buckling under earthquakes is considered to be a phenomenon which takes place under the controlled horizontal displacement. The authors investigate experimentally and analytically the relation between horizontal displacement and buckling strength of outer columns in multi-story frame, and, using these results, propose a design formula for outer columns subjected to the over-turning moment under earthquakes.