This paper proposes a new structural engineering framework for performance-based design(P.B.D.) of building structures. This framework was proposed under the 3-year Japanese Government Comprehensive Research and Development Project on "Development of a New Engineering Framework for Building Structures" launched in the fiscal year of 1995. The primary objective of the project is to create a system in which the performance of buildings is clearly stated, and consumers, i.e. occupants, are well informed of how their buildings will perform and how much it will cost to attain their performance.

A new framework is proposed in CHAPTER 1. The framework emphasizes the establishment of target performance, the performance evaluation and the performance statement as the main three elements. It also stresses that a social system (an institutional framework and support systems) needs to be provided to enable P.B.D. to be practiced efficiently. The implementation of the framework is expected to promote innovation, progress and globalization in building structural engineering. The new framework will also bring other benefits, such as improved design techniques, greater design flexibility, and international harmonization. It is also important for building structural performance to become one of the most important indexes for consumers to define a building's value.

In the project, the following three main issues were studied. The results of those researches are described in CHAPTERS 2,3 and 4.

To examine the issues related to the target performance levels m structural design, the Target Level Subcommittee was organized in the project. A framework for determining levels, which consists of the fundamental ideas concerning target levels, and various factors that may be used for deciding levels and those used in actual evaluations, is described in CHAPTER 2.

To examine the issues related to structural performance evaluation system for buildings, the Performance Evaluation Subcommittee was organized in the project. A framework for establishment of target performance, verification of performance, and statement of the evaluated performance, is described in CHAPTER 3.

To examine the issues related to the new institutional framework and support systems, the Social System Subcommittee was organized in the project. A new 'Social System" which is composed of various supporting devices for performance based design practice like codes/rules, institutions, technical tools, information systems, etc, is described in CHAPTER 4.