Experimental seismic investigation of a full-scale woodframe building

An impediment to the development of performance-based seismic design for woodframe buildings is the lack of understanding of the factors that affect the seismic behavior of woodframe structural systems. Few numerical seismic analysis models capable of considering all the factors influencing the seismic behavior for three-dimensional woodframe structures currently exist. Furthermore, only limited experimental data have been generated at the system level and never on a structure with realistic dimensions. This paper discusses the results of a shake table testing program on a full-scale woodframe structure conducted within the NSFfunded NEESWood Project. The test structure considered was a full-scale two-story townhouse, having approximately 1800 ft2 of living space with an attached two-car garage. It was assumed to be located on a level lot with a slab-on-grade and spread foundations and to have been built as a "production house" in either the 1980's or 1990's, located in either Northern or Southern California. The design was based on engineered construction. The size and weight of the test structure required the simultaneous use of the two three-dimensional shake tables at the Structural Engineering and Earthquake Simulation Laboratory (SEESL) at the University at Buffalo. The testing program focused on the various construction elements that have significant influence on the seismic response of woodframe buildings. Five different testing phases were conducted to investigate the influence of the following elements on the seismic behavior: Phase 1 - Engineered wood structural (shear) walls alone; Phase 2 - Wood structural walls incorporating viscous fluid dampers; Phase 3 - Installation of gypsum wallboards to engineered wood structural walls; Phase 4 - Installation of gypsum wallboards to interior partition walls and ceilings; and Phase 5 - Installation of stucco as exterior wall finish.