Kiho Jung

Evaluation on structural performance of compressed wood as shear dowel

Abstract This study addresses the application of compressed wood (CW) made of Japanese cedar, as a substitute for high-density hardwood, to shear dowel. A double wood-to-wood shear test was performed to evaluate the mechanical shear properties of CW perpendicular to the grain, and the results were compared with those of several types of dowel material. CW with its annual ring radial to loading direction (0°) had a unique double shear performance characteristic, and showed good properties as a dowel material by virtue of its strength and rich ductility. In contrast, CW with its annual ring tangential to loading direction (90°) and maple exhibited brittle failure. While thickness of the base member was varied, the ductility of the joint became stable for diameter over 36 mm and 24 mm thickness for the main and side members, respectively. When the density of the base member increased, its stiffness, yield load, and maximum load exhibited proportional improvement with different inclinations; however, in the case of a maple dowel, the increases were small. When the density of the base member was increased, the ultimate load had positive linear tendency, whereas plastic modulus decreased. Consequently, almost constant energy absorption was observed in spite of the increased density. The optimum load-carrying capacity and ductility of a compressed wooden dowel joint could be designed by introducing an appropriate base member.

Development of a joint system using a compressed wooden fastener I: evaluation of pull-out and rotation performance for a column—sill joint

Compressed wooden plates and dowels were used to connect members in post-and-beam structures as a substitute for a steel fastener. In order to take advantage of the characteristic properties of compressed wood and to achieve optimum joint performance, two compressed wooden plates were used in each joint to give multiple shear planes for each compressed wooden dowel. Consequently, this type of joint showed very good properties in pull-out and momen-trotation performance, and its engineering design could be further optimized. This joint is expected to be introduced to many kinds of structural systems, including long-span frame structures made of domestic timber found in Japanese residential houses.

Development of a joint system using a compressed wooden fastener II: evaluation of rotation performance for a column-beam joint

In the present study, a plate and a doweled fastener made of compressed wood (CW) were newly introduced into a moment resisting column-beam joint system for a small portal frame structure. A mechanical model that contains not only an axial spring, but also a rotational spring, considered resistant factors to verify how each element resists rotation. Theoretical performance was compared with experimental data. Consequently, the mechanical model was shown to be suitable and the combination of resisting factors was found to be very effective; i.e., the rotational spring provides more influence on the stiffness and moment compared with the axial spring. Large moment and ductility can be achieved by virtue of the high embedding performance of the CW plate in the rotational spring, accompanied with the high shearing performance of the CW dowel in the axial spring.

EVALUATION FOR LATERAL SHEAR PERFORMANCE OF PREFABRICATED MUD SHEAR WALL (PMSW)

This research was performed to evaluate the shear performance of prefabricated mud shear wall (PMSW) which was developed to introduce more vigorously into the modern timber house with appropriate modification. In order to precisely investigate the performance of PMSW, relative relationship between rotational and shear behavior of mud in side of frame was considered with the parameter of number of screw. Consequently, PMSW-2 and PMSW-3 which are fixed by 16 and 24 pieces of screws for one PMSW unit showed high performance compared to the CMSW. On the behavior of mud unit for shear deformation of timber frame, rotation of mud was dominant until yielding of wall at both CMSW and PMSW, then yielding of whole was occurred along with shear yielding and failure of mud.