Performance-based seismic design of mid-rise light-frame wood buildings: An overview of the NEESWood project

The NEESWood project is a four-year five-university project in the United States whose objective is to develop a logical, economically viable, Performance-Based Seismic Design (PBSD) philosophy for mid-rise light-frame wood (woodframe) construction. The project began in 2005 with the testing of a full-scale, two-story, townhouse building spanning two 7 m × 7 m shake tables at the University at Buffalo. The results of the tests were used to provide data to develop an understanding of the contribution of nonstructural wall finishes, the combination of shear and bending deformations in shear walls, the effect of incorporating passive seismic protection systems, and to help validate a new software package, SAPWood, which serves as a research and design tool within the project. Within the project a tiered PBSD is being proposed ranging from Direct Displacement Design (DDD) in which a shear wall backbone database is applied using equivalent linearization based on energy balance and modal combination rules to a systematic Incremental Dynamic Analysis (IDA) approach using full non-linear 3-D time domain analysis, are being proposed. A system identification approach that utilizes non-linear time domain simulation is also being explored. Each of the methods will be applied to the design of a six-story, 23-unit, 1400 square meter condominium. This paper provides a general overview of the NEESWood project including brief descriptions of the six-story building design, the use of passive seismic protection devices in woodframed structures, previous test results, the software package SAPWood, and societal risk implications of the new design procedure. Plans for full-scale testing of a six-story building at the E-Defense shake table test facility in Japan, serving as the capstone experiment to the project, will serve to validate, to the extent possible, the design philosophy proposed within the NEESWood project.