In wooden light frame constructions, wind or earthquake forces are transmitted through the boundaries between upper floors and walls, walls and lower floors, floors and sills, or sills and foundations. At the boundary between the bottom plate of a shear wall and a floor diaphragm sheathed with plywood or another wood based panel, for example, the lateral force borne by this shear wall is transmitted by both nailed or other mechanical joints and friction between the bottom plate and the floor sheathing panel. In this study, static cyclic tests were conducted to estimate the effect of frictional force on the lateral resistance at this boundary. The observed apparent frictional coefficient between SPF bottom plates and softwood plywood sheathing panels averaged 0.285 and varied in a wide range from 0.2 to 0.35. The minimum value, 0.2, is roughly close to the dynamic frictional coefficient obtained from pure frictional tests of the same combination of materials. The wide variation of apparent frictional coefficient seems to result from irregular contact conditions between bottom plates and sheathing panels or eccentricity of lateral forces. Static cyclic tests showed a great effect of friction on hysteretic damping capacity.

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To examine relationship between dynamic behavior of roof snow and seismic response of wooden houses by strong ground motion, the authors carried out shaking table test. The structure of one-story and flat roof with steel sheet roofing was used as the model in the test. Harmonic vibration was used as seismic wave in the test. Adfreezing of roof snow and roof surface projection that restricted roof snow sliding was recreated in the model. Relationship between sliding restriction conditions and breaking form of roof snow was observed. Sliding conditions after roof snow break were recreated in the test that changed roof surface condition and roof snow weight. Relationship between friction resistance of sliding surface and response characteristics of the model was examined by the test.The roof snow break from weak layer and one section in wet snow might occur in strong ground motion. In the evaluation of seismic performance of wooden houses during snow season, necessity to consider the ground motion scale, sliding surface characteristics of roof snow was clarified.

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