Basic Study on Seismic Zoning Factors

Abstract

We selected 5sites,that is Niigata. Tokyo. Nagoya. Osaka and I Fukuoka. as study areas. Then we investigated the regional differences of the seismic load by calculating on the condition which the probability of damage corresponding to the damage of the low-middle RC building is equal in each site. Conclusions are as follows: (1) Recommendations for Loads on Huildingsbv A.I.J. adopt 100years return expected valueas the basic valueofthe seismic load. When the zoning factor of th seismic load is made only 1. the return period is insufficientfor 100years and necessary for about 300years.(2) As for the present design by 2 steps. thouuh recommendations by A.l.J.are effective against the regional dietbrences toward the design of the first step. another zoning factor is necessary for the design of the second step.