A clarification of collapse modes and an establishment of evaluation methods of earthquake resistant properties on wooden houses

Abstract

The load tests and analyses were conducted for the application of non-linear dynamic response analyses to timber structures in order to estimate the possibilities of wooden houses collapse. A full-sized 2-story Japanese conventional wood frame house was subjected to static lateral load tests and summarized as: 1) The contribution of displacement in each wall line had a correlation to the eccentricities of shear wall layouts roughly. However, the specimen with the same eccentricity occasionally had a different distribution of displacement, so that the eccentricity couldn't evaluate the displacement distribution exactly. 2) The shear walls below the lean-to roofs were effective against the load applied to the roof level and were not effective against the load applied to the 2nd floor level. So, it was clarified that the stiffness of lean-to roof as a diaphragm was low. 3) The addition of a floor diaphragm significantly made the unbalanced deformation distribution relax. However, raising the stiffness of the floor diaphragm made the differences slightly smaller. This is the reason why the stiffness of the floor diaphragm is relatively low. 4) The shear walls perpendicular to the load direction made the stiffness and the allowance shear forces high. Full-sized braced shear walls were subjected to the dynamic fracture tests on the shaking table and summarized as: 5) All of braced shear walls tested in this report did not collapse but failed in braces or columns with pull-out by approximately 1.5-2 kN lateral force. 6) In all tested walls, the shear deformations with the compression stress in the brace were smaller than those with the tension stress in the brace, in spite of the brace with buckling . So, the walls failed in the direction of the tension stress in the brace. 7) The bottoms of columns and braces didn't give priority to pull out rather than the top of them. 8) The brace angle depending on the wall length had a possibility to change the fracture position and behavior. 9) Fatigue failures of metal fasteners were not seldom seen under static loads. However, they occurred in these dynamic tests.