Sequential Phased Displacement Cyclic Tests of Wood-frame Shear Walls with Various Openings and Base Restraint Configurations

This study examines the performance of long, full-sized, shear walls with and without openings, and with and without overturning restraint tested under monotonic and reversed cyclic loads. To improve the accuracy of designs when no overturning restraints are provided, tests of shorter wall specimens with corner framing were also tested. The results of this investigation provide useful information in determining at what wind and seismic force levels the different numbers of overturning restraints are required for a given wall configuration. This also provides information necessary to determine which regions of the United States need not require overturning restraint due to low lateral load levels and which regions should require overturning restraint due to high wind or seismic loads. Six long, fully-sheathed and perforated walls were tested under Sequential Phased Displacement (SPD) loading, providing quantitative information about earthquake performance and the effect of overturning restraint. Based on the testing results, the authors conclude that 1) Ultimate capacity of walls subjected to SPD loading increased with increasing overturning restraint; 2) Cyclic elastic stiffness was typically higher than monotonic elastic stiffness for walls without restraint; 3) Gypsum panel sheathing was observed to perform poorly during the reversed cyclic tests; 4) The typical failure mode for walls with no tie-down anchors was the almost complete separation of studs and sheathing from the bottom plate; 5) Monotonically tested walls sustained higher loads beyond capacity than walls subjected to SPD loading.

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