Following the performance-based design currently adopted in the Technical Standards and Commentaries for Port and Harbor Facilities in Japans, design method of structural members comprising a caisson was discussed. Firstly a comparison between the former and the current design methods for structural reinforced concrete (RC) members was reviewed; namely allowable-stress design and limit state design, respectively. Then the critical index for verification with respect to limit states of structural member in caisson was investigated. According to the result of investigation, serviceability limit state of structural member turned out to be the most severe state frequently to determine the structural details such as cross-section and bar arrangement of structural RC member. Especially the crack width, one of the serviceability limit states, had a great impact on bar arrangement. These investigations put particular emphasis on the importance of in-depth discussions of crack width of concrete member in terms of serviceability as well as durability. These points were summarized, with special references to the standard specification by Japan Society of Civil Engineers (JSCE) and other related studies.
Key Words: caisson, performance verification, serviceability limit state, crack width