抄録
The concept of maximum mean largest value introduced by E. J. Gumbel is applied to the design of reinforced concrete structure, and is named as the worst-state design and/or extreme value design. The characteristics of the worst-state design are as follows; 1) The structure is designed by using minimum material strength and maximum external force. 2) Minimum material strength and maximum external force are derived as the minimum mean smallest value and the maximum mean largest value, respectively, by using Lagrange multiplier method under the condition that failure probability of the designed structure is never exceed a certain value P_f in any case. 3) Material strength consists of two independent parameters such as steel rod and concrete. External force consists of two independent parameters such as traffic load and earthquake load. In this paper, first, maximum mean largest value is derived by introducing new characteristics A, B, C and D in order to reduce the excessive estimation of the largest value; second, the concept is extended to the estimation of the upper bound value of failure probability; third, the concept is also extended to two parameters problem, where two kinds of material strength and/or two kinds of external force are included; fourth, an example of design of reinforced concrete girder bridge is provided; and fifth, some execution error problems such as location error of steel rod of reinforc-ed concrete girder are discussed.
