傳統疊斗式木構造接頭抗彎行為研究

Flexural Performance of Traditional Dieh-Dou Timber Joints

傳統疊斗式木構架是以楹、通、斗、栱、束、瓜筒及其他構件在屋架處彼此搭接，構件數量多且接合行為複雜，柱在此區域需要與通、枋等水平構件在水平兩向以及不同高程位置接合而設有許多榫口，過去實驗研究探討柱通單一接點之彎矩行為，主要由通材的承壓強度決定接點性能，當柱鑿有水平兩向榫口，柱有效斷面積減少對於接點行為影響則未有討論，同時過去地震發現柱端上下層榫口距離接近的案例中，有柱端垂直向劈裂的情況，接點的極限狀態不同可能影響接頭性能。本研究規劃數座足尺柱通接頭試體，以靜態反覆加載方式評估上述形式接頭之破壞的模式以及對性能的影響。實驗結果顯示，當柱端水平雙向都設有榫口時接頭的強度與初始剛度約比僅單向榫口接頭降低5%，影響並不顯著。當接點處具有上下雙層、雙向榫口時，因柱端上下層榫口間距接近，導致榫口間的塊狀剪力破壞，接頭之強度與剛度分別降低12%與26%，柱通接頭性能評估時應考量柱端上下層榫口間距以及破壞模式納入考量。

In the Dieh-Dou type timber frame, the columns not only connect with multiple layers of beams along the in-plane direction but also connect with beams in the traverse direction at the same level. In this study, the effects of small column effective section area and small joint distances on the flexural performance of the joints were investigated. A two-part series of full-scale, quasi-static cyclic tests were conducted. The first part involved the column connected with single layer of beam but with different effective column section areas. In the second part, the double-layer beam-column joint specimen with a 6 cm clearance was tested. Each set of parameters measured used three identical specimens. The test results indicate that effective column section area affects the stiffness and strength by only about 5%. By comparing these results with the results of the single-layer beam specimen, the double-layer beam specimens with short clearance exhibited a decrease in strength and stiffness of 12% and 26%, respectively. Block shear failure was observed in the column.