Abstract
Earthquake damage estimation after a major earthquake is important for prompt rescue. We developed a hysteresis characteristics model for existing wooden houses that can reproduce actual behavior under large displacement for earthquake damage estimation. We conducted the shaking table tests of wooden houses with different strength and input ground motions in order to get experimental results used in the seismic response analyses.
The types of shear walls and the amount of shear walls varied series were conducted. The specimens of each series were shaken at the same time. The input ground motions were the K-NET Anamizu, the K-NET Hiroo, and the simulated earthquake motion. The K-NET Anamizu recorded in the 2007 Noto-Hanto earthquake has large 1-1.5 sec. responses which have close relationship with heavy damage to wooden houses and buildings. The K-NET Hiroo recorded in the 2003 Tokachi-Oki earthquake is very short period of 0.2 sec dominated motion. The simulated earthquake motion (phase: El-Centro NS) is period of 0.4 sec dominated one, the type of which has never been recorded. The result that the displacement of the specimens increased as the strength decreased was found under the K-NET Anamizu. Buckling of a brace and a damaged nail were seen in the specimens with low strength. The displacement of all specimens were small and they were not damaged under the K-NET Hiroo. The unusual result that the displacement of the specimens increased as the strength increased was found under the simulated earthquake motion in contrast under the K-NET Anamizu. This is because the natural period becomes shorter as the strength increased in wooden houses.
We tried to reproduce the experimental results by seismic response analyses. We used the modified Takeda-Slip model for wooden houses as a hysteresis model. We modified the hysteresis characteristics model as follows:
(1) Modification of the formula of unloading stiffness
(2) Consideration of deterioration under cyclic load
(3) Consideration of the asymmetrical behavior in the case of plywood We could reproduce the experimental results accurately by the modified model.
