Performance of partially and fully anchored wood-frame shear walls under earthquake loads

The objectives of this study were to evaluate the performance of wood-frame shear walls under monotonic, cyclic, and earthquake loads by: 1) comparing performance under each loading protocol; 2) evaluating effects of anchorage; and 3) evaluating performance qualitatively and quantitatively with respect to code-defined performance measures. Tests were conducted on 2440 by 2440 mm walls with 38 by 89 mm (2 by 4) Douglas-fir studs at 610 mm on center. Each wall was sheathed with two 1220 by 2440 by 11.1 mm oriented strandboard (OSB) panels and two 12.7 mm gypsum wallboard (GWB) panels installed vertically on the face opposite the structural panel sheathing. Eight walls were tested using two historical subduction zone ground motions scaled to a 10 percent in 50 year probability of exceedance for Seattle, with a 4545 kg seismic mass. Two partially anchored and two fully anchored walls were tested using each earthquake time history. Earthquake tests exhibited lower peak strength and initial stiffness than similar walls tested monotonically. Various ground motions produced similarly shaped asymmetrical load-deflection envelopes. Fully anchored walls exhibited a limit state with severe pinching in the hysteresis curve beyond which performance variability increased dramatically. Maximum transient drift for six of eight tests exceeded the 3.0 percent drift limit for collapse prevention performance in ASCE 41. Maximum drift was similar between fully and partially anchored walls.
The U.S. Census Bureau (2004a) estimated that $538 billion of new housing would be constructed in the United States in 2004. A large percentage of the 1.3 to 1.5 million [...]