1 Cyclic Tests of Full - Scale Light - Framed Wood Construction

Nine full-scale light-framed wood construction (LFWC) specimens were tested cyclically to study the effect of the upper storey and the vertical load on the performance of wall framed shear wall (WFSW) in the first storey. Results showed that the effects of the upper storey with the vertical load on the performance of WFSW were to: (1) increase the elastic stiffness, (2) reduce the ultimate deflection and yield deflection, and (3) make the uplift of the studs at the end of walls and beside the openings small and uniform along the wall in the first storey. Meanwhile the upper storey or the vertical load had little effect on the shear strength of WFSW. The test results indicated that in the lower storeys the number of hold-downs can be reduced to some extent in seismic design. INTRODUCTION The WFSW is assumed as the primary means for resisting lateral loads in the LFWC in the past years and today. Lots of studies focused on the performance of the single piece of WFSW, and comprehensive biographies of works in this area can be found in Carney (1975), Peterson (1983), and Van de Lintd (2004). These studies played an important role in making engineers understand the behaviors of the single piece of WFSW under static monotonic load and cyclic load, and also provided a conservative indication of the load and displacement capacity of the WFSW in design. In the field, the WFSW always works in the complete structural system, and it is kept under restraints from transverse walls, floor diaphragms, upper storeys and vertical loads. In recent years, several researchers (e.g., Nelson et al. (1985), Dolan et al. (1997c), Ni et al. (2002), Dean et al. (2005), Johnston et al. (2006)) have experimentally and theoretically investigated the effects of transverse walls, floor diaphragms, upper storeys and vertical loads on the performance of the WFSW. The works mentioned above indicated that transverse walls, floor diaphragms, upper storeys or vertical loads can make the performance of the WFSW very different from that of the single piece of WFSW. Tongji University, Shanghai, China, cooperated with FPInnovations Forintek Canada Corporation initiated a research program in 2004 on the seismic resistance of the LFWC. The objective of the research program was to provide data needed for the quantitative assessment of the seismic design code provisions for the LFWC in both China and Canada. Reported in this paper were the results of the cyclic tests of nine full-scale LFWC specimens, the objective of which was to study the effects of the upper storey or the vertical load on the performance of the WFSW in the first storey. Realization of these effects will improve the understanding of performance of the WFSW in the complete structure under seismic load and achieve a more rational analytical methodology and a more cost-effective design. In the following text, the WFSW always means the shear wall parallel to load direction in the first storey of the test specimens. State Key Laboratory of Disaster Reduction in Civil Engineering, Shanghai 200092, China