1. Introduction
In Japan, high performance damping buildings and houses are required to improve seismic safety and to minimize damage, because of many occurrences of severe earthquakes. On the other hand, Japanese wooden houses do not have enough shear walls to keep large and many openings and semi-rigid timber portal frame has been developed and has increased. However, semi-rigid timber frame structure is relatively soft. This paper presents seismic performance of semi-rigid timber frame structure with damper through full-size shaking table tests. We compared response deformations during moderate and severe ground motions among only frame, frame with oil damper and frame with shear wall to verify damping effect of oil damper.
2. Overview of damping wall with oil damper
Damping wall system consist of a oil damper set horizontally through a ∧ shape steel member installed between two columns and below a beam of wood (hereinafter, referred to as "∧-type damping wall"). ∧-type damping wall is a system where damper deformation becomes almost the same as the story deformation. ∧-type damping wall has a high damping force compared to other damping walls that exist in the field of wooden houses nowadays in Japan. Relief force of the oil damper is 12 kN and the relief velocity is 70 mm/sec.
3. Overview of shaking table tests
Planar shape of box-shaped one-story specimen is 5460mm (direction of vibration) × 3640mm (Orthogonal direction of vibration), and its height is 2835mm. Ground motion is input in one direction. There are three types of structures set in series in the direction of vibration, the outer two structures are semi-rigid timber frames and the structure at the center is ∧-type damping wall or seismic wall of plywood. The detail for each structure is described as follows. (1)Semi-rigid timber frame with oil damper. (2)Semi-rigid timber frame with seismic wall of plywood. (3)Semi-rigid timber frame only. The total weight of specimen is 87.0kN.
Moment resisting joint of semi-rigid timber frame is using lagscrewbolt, metal connector and nut. Procedure of construction is embedding the lagscrewbolt into the column and beam, and setting up a metal connector, and binds with nut. Size of column is 120mm × 300mm and wood specimen is engineering wood of European red pine (E105-F300). Size of beam is 120mm × 360mm and wood specimen is engineering wood of European red pine (E105-F300). For column base anchor bolt (M14, SNR490B) with growth capacity was used. Semi-rigid timber frame is considered to have a Co=0.51 seismic performance for elastic frame analysis. Seismic walls are placed in the center of structure row and are bonded both sides of plywood (t=12, N50 nail, @150). Seismic performance of this wall is almost equivalent to ∧-type damping wall. ∧-type damping wall and Seismic wall are considered to have a Co=0.11 seismic performance.
Input seismic wave are three observation waves and one artificial wave. Observation waves are "ELCENTRO 1940 NS", "TAFT 1952 EW" "JMA Kobe 1995 NS". Artificial wave is "BSL wave" whose acceleration response spectrum is provided in the Building Standard Law. Seismic waves were scaled to two levels that represents medium and extreme earthquakes.
4. Results and Conclusions of shaking table tests
Maximum response deformation of " Semi-rigid timber frame only " for Taft wave(25kine) is 1 / 106rad, for BSL wave(80%) is 1 / 45rad. This is large response deformation by specific seismic wave. "Semi-rigid timber frame with oil damper" reduces the response deformation for all evaluated seismic waves and can avoid damage to the structure.
