Investigation of the structural performance of beam and column connections using hidden threaded rods.

摘要

A traditional wooden beam and column joint was revised using an embedded threaded rod with the assistance of dowels, and the structural performance of the joint in resisting the bending moment was examined in the study. Beam and column members of Japanese cedar and southern pine timber with a size of 120x120 mm were used to construct a T-structure which was then subjected to a cantilever load. The results indicated that the joint tightened with a threaded rod with 150 mm of embedded length in the side beam member showed a higher bending moment compared to those with 120- and 180-mm embedded lengths. The bending moment resistance of a joint in which a threaded rod was embedded at the upper location of the cross-section on the beam member was 4 times that at the lower location while exhibiting only 25.3% of the moment-rotation coefficient value. The bending moment capacity of joints tightened with a 60x60-mm washer was 40.2 and 36.2% higher than values of joints with 50x50-and 60x80-mm washers, respectively. The critical failure of a joint tightened with an embedded rod may have been due to the weak compressive strength perpendicular to the grain on the column member. When epoxy reinforcement was applied to the joint, the bending moment resistance of the Japanese cedar member joint with 2 embedded threaded rods improved 39.5%, and the internal rotation angle and moment-rotation coefficient were reduced by 21.6 and 40.6%, respectively. Overall, similar bending resistance values of beam and column joints assembled with both Japanese cedar and southern pine members were found after epoxy reinforcement was applied. The results also demonstrated a reduction of 68.4% in the moment-rotation coefficient for the joint with additional epoxy reinforcement.