建築物の振動減衰性に関する研究

Abstract

The present investigation is concerned with seismic damping of actual buildings. The most important factors in designing earthquake-proof buildings are natural periods and damping factors of buildings. Some kinds of method to estimate the natural periods of buildings in designing buildings have already been investigated. However, research has started quite recently into a few methods to estimate the seismic damping factor of buildings. The present paper describes one method of estimating the seismic damping factor in designing earthquake-proof buildings. The results of the first half of the present investigation tell us that seismic damping resistance mostly depends on the decreasing effect of energy of waves at the boundary between the ground and the bottoms of the buildings. From the considerations mentioned above, an empirical formula to estimate the damping factor h in designing earthquake-proof buildings is obtained as follows : [numerical formula] where W and T_D denote the total dead load in wt. tons and the natural period in sec of the building estimated in designing the building, while A is the area of the bottom of the building in m^2, and ρ_2 and V_2 are unit-volume weight in wt. ton/m^3 and S-wave velocity of the ground in m/sec. The empirical formula is made by trial and error, so the formula may be improved by investigating the structure of buildings and the ground with increased data.