柳杉造林木釘接組合樑之研發

本研究使用國產柳杉人工林疏伐木為原料，以金屬連接件接合方式集合成各種形式斷面之組合樑，並對其應用於建築結構之性能加以分析驗證，以期能發展出輕量及高性能之工程用構造元件。研究結果指出，木質組合樑以金屬連接件方式進行接合，自攻螺釘的釘著力與最大剪斷力皆高於鋼釘的釘著力與最大剪斷力，且無論鋼釘或自攻螺釘，弦切面的釘著力約等於徑切面的釘著力，橫切面的釘著力則最小。當金屬連接件距離增加（釘距大於10 cm），整體平均最大剪斷力隨之降低，顯示出木質組合樑設計金屬連接件之釘距愈大，金屬連接件提供抵抗木材構件間滑移變形之性能無加總效應。從實尺寸組合樑之抗彎試驗，II字型與口字形之抗彎強度高於工字型之抗彎強度，而II字型與口字型的樑腹設計位置對於最大載重能力並無顯著差異；另外，有無膠合劑補強之抗彎試驗，添加膠合劑有顯著提升最大載重能力；上樑翼等級、樑腹等級對於抗彎性質無影響，下樑翼等級則有影響；金屬連接件間距30至50 cm對於組合樑抗彎性質無差異，但間距大於50 cm則有下降趨勢。整體來說，膠合自攻螺釘組合樑之膠合劑提供整體結構的剛性，自攻螺釘提供結構系統的延展性。

關鍵字

抗彎強度；接合強度；組合樑；柳杉；自攻螺釘

並列摘要

To analyze and evaluate mechanical performances of built-up beams which be applied in building structure and becomes more light and high ability in engineering. The study takes plantation Cryptomeria japonica as main ingredients, and cooperates with metal connectors to design three type of designed cross-sections. The results indicate that (1) the withdrawal resistances and the maximum shear force of self-tapping screw are higher than steel nail; (2) the withdrawal resistance of tangential surface as same as radial surface, but higher than cross surface. In addition, when using two connectors, the maximum shear force was higher than using single connector, but the maximum shear force decreased with increasing spacing between two connectors. When the spacing between two connectors are more than or equal to 10 cm, the shear resistance shows nonsignificant difference between using two connectors and single connector. Showing no additive effect on the shear resistance if the spacing between connectors was excessive. Moreover, double I-beams and box beams showed that higher load-bearing capacity and bending strength than those of I-beams. The load-bearing capacity of double I-beam and box beam are nonsignificant. Also, the result of using RF resin shows that the maximum load of glued-screw I-beams and I-beams are significant difference. The levels of top flanges and webs are no significant effect on mechanical properties in bending, whereas the levels of bottom flanges showed significant effect on mechanical properties in bending. In addition, there are no significant difference among groups of different spacing between connectors from 30 to 50 cm, but bending strength will decrease gradually when spacing over 50 cm. To sum up, glue increased rigidity and self-tapping screws provided ductility for built-up beam structure system.