In order to resist the destructive forces of earthquakes in Japanese small scale timber structures, structural performance (as eismic performance) is demanded. Timber structures have relatively low joint-performance compared to that of RC (reinforced concrete) or steel structures, and focus needs to be set not only stiffness but also on their ductility.

Consequently, various types of joints and a lot of effort have been put into improving the joint performance of a traditional wood-to-wood joint in order to apply it in modern joints using steel fasteners.

Recently, the new types of timber joint with less steel usage, and more newly developed materials have been vigorously introduced as improvement based on environmental points of view.

Hence, this research is focused on a shear-key type of joint. The shear-key type of joint has been widely used in traditional as well as in modern joinery until now due to its ease of assembly and relatively high performance as a mechanical joint method [1] [2] . In this type of joints, key fastener has a very important role because of its bending, compressive and shearing capacity, which highly influences the joint’s performance.

Aiming to improve the key-joint’s performance, a hybrid pin (HP), composed of a compressed wooden dowel [3] [4] inserted in a stainless steel pipe is suggested in this research.

Firstly, double shear perpendicular to the grain of HP was studied; focusing on the balance between shear performance and the ratio of base member’ thickness for dowel’s diameter [5] . Then, moment-resisting performance of mortise and tenon joint type with a HP was evaluated [6] [7] .

Moment resisting joint using HP was suggested. Figure 15 shows each type of specimen with different configu-

Note: K: initial stiffness, P_y: yield strength, P_max: maximum strength, E: energy.

ration for the dowel’s insertion. The specimen was made of spruce (Piceaabies) glue-lam. The jointing process, involved the manufacturing of mortise-and-tenon on each specimen, their assembling, drilling of holes, and insertion of HP. Each specimen was placed on a frame with hydraulically-operated jack, as shown in Figure 16. In order to give rotational moment to the joint, the beam was fixed with a long metal arm and each of the 3 hinges was fixed by a 16 mm-diameter steel pin.

Horizontal load was applied by hydraulically controlled Jack at the top of the column. The applied load, and horizontal displacement were simultaneously measured.

A cyclic loading schedule was applied as follows: ±1/300, 1/150, 1/75, 1/50, 1/25, 1/10 (Rad) at a first step, afterwards a constant loading was applied until to the specimen’s failure or limited displacement at test machine. Figure 17 shows the details of the loading during the test.

Figure 18 shows moment vs. rotational angle of each type of specimens. Table 6 displays values of stiffness, yield moment, maximum moment, and energy from rotational test. On the different length of mortise with same

number of HP, HPJ2 shows 1.42 times higher initial stiffness than HPJ1. It is thought that additional length of mortise in HPJ2 give influence on rotational performance. Compression strength on the flat edge in mortise of HPJ1 is relatively lower than that of additional edge in HPJ2 on the imbedding behavior between mortise and tenon originated from rotational moment [6] [7] [9] .

Comparing specimens with different number of dowels, HPJ3 shows 1.39 times higher initial stiffness, 1.35

times higher maximum moment, and 1.63 times higher yield moment than that exhibit by specimen type HPJ2.

Specimen HPJ3 with 4 pins inserted exhibit a stiffness of 255.94 kNm, a yield moment of 7.41 kNm, and a maximum moment equal to 12.26 kNm.

In this research, the performance for the newly developed hybrid pin (HP) joint was evaluated.

The results from the double shear test loaded in direction parallel to the grain of the base member, specimen type m3s2 exhibit stiffness equal to 1400 kgf/mm, and yield strength of about 922 kgf. On the shear test with loading direction perpendicular to the grain of the base member, the specimen type m3s2 showed a stiffness of about 680 kgf/mm, and a yield strength of about 840 kgf.

Mortise-tenon joint with inserted hybrid pin showed high moment-resisting-performance from the rotational tests results. These values resulted in a stiffness of 255.94 kNm, and a yield moment of 7.41 kNm in the specimen type that includes 4 pins.

Consequently, the hybrid pin showed satisfactory performance as shear-type fastener by virtues of not only relatively high stiffness but also rich ductility originated from each different property of steel pipe and compressed wooden material.