抄録
The aim of this study is seek for necessary and sufficient conditions of the optimum design loads of buildings and structures other than socially important ones. This paper build up ten hypotheses and assumptions in order to attain the goal. The fundamental assumption and hypotheses are as follows; 1) the temporaly loads are indipendent random variables. 2) the safty of occupants, the regional or urban security and reconstruction measures should be assured indipendetly with the structural strength design of indiuidual buildins and structures. 3) the economically optimum design load condition should minimize total building cost which is composed of initial investiment (I), estimated damages by disasters (D_n), maintenance expenditures (R_n) and earnings (-E_n). this hypothesis is denoted by equations (3), (5). The obtained results are as follows; 1. When he determinant Det≤0, the optimum design for temporaly loadts does not exist. 2. When Det>0, the necessary and sufficient condition for the optimum design is given by the equilibrium formula (7)-(12).
