本研究針對木質緊固件雙剪行為與面內複層集成元之剪力特性探討較為微觀之性能研究。且為提升國產材加工效率並簡化製作流程，本研究探討木榫之烘乾程序，期望透過簡易烘乾設備即能完成木榫製作，無需倚賴複雜加工機械。同時，本研究以木榫作為緊固件，針對其於雙剪與對角壓縮行為中之力學表現進行分析，探討緊固件樹種、孔徑尺寸及是否經過烘乾處理等因素對非膠合集成構件之影響。雙剪試體尺寸為寬120mm ×長180mm×高140mm，所使用之木質緊固件分別為桃花心木與柳桉兩種樹種，木榫貼合度差異為木榫直徑之19.85 mm與20.0 mm，並區分為烘乾與未烘乾兩類，再分別打入國產柳杉集成元中，並透過儀器紀錄荷重數據，並觀察破壞行為。
對角壓縮試體尺寸則為寬308mm×長150mm×高308mm，同樣採用上述變因之木榫緊固件，打入國產柳杉集成元後組裝成試體。試體旋轉45度後置入金屬治具中固定，再以20噸萬能試驗機施加垂直軸向荷重。試驗中同樣透過儀器紀錄荷重數據，並觀察破壞行為。
本研究比較柳桉與桃花心木作為木榫緊固件的力學表現，發現柳桉的極限強度和延展性普遍優於桃花心木，後者雖在線彈性階段降伏強度稍高，卻易發生脆性破壞，韌性不足較難以被預測，因此並不建議作為建築用材。對於木榫直徑影響，雖原先預期直徑20.00 mm之試體貼合度較高，極限強度應略高於19.85 mm之試體，然而實驗結果顯示，前者極限強度反而略低於後者，但其差異僅約2.1%與6.8%(未烘乾與烘乾)，影響並不顯著。而烘乾變因影響下，20.00mm與19.85mm柳桉木榫降伏強度提升1.31%與9.5%、極限強度略降5.9%與1.1%，勁度大幅增加但延展性較無規律性；而桃花心木降伏強度下降3.35%、極限強度提升1.5%，但勁度同樣大幅增加、而延展性下降，因此可知烘乾對於木榫並無絕對增益或是減損之效果，且效果程度也不盡相同。
試體降伏強度與Eurocode 5理論十分接近，安全邊界值達0.80 ~ 1.07倍，且極限強度安全邊界比值皆大於理論值，柳桉到達1.3倍甚至2倍。破壞模式中，柳桉大多對應Eurocode 5第III模態，表現出良好的延展性；相對之下，桃花心木偏向脆性破壞，力學表現缺乏穩定性及可預測性，基於以上原因建議柳桉作為建築結構使用。
經比較雙剪行為與對角壓縮行為後發現，理論上複層構件在對角壓縮試驗中，其極限強度應約為雙剪極限位移時之1.5倍。然而，由於對角壓縮試體相較雙剪試體屬於多界面構件，除木榫本體貢獻外，層間摩擦力亦參與承載行為，導致柳桉試體實測強度超出預期倍率，產生額外承載能力。反之，桃花心木試體因材料特性導致脆性破壞，其極限強度未達理論倍率。
綜合分析結果可知，雙剪行為與複層構件之整體強度表現，主要受緊固件樹種與其密度影響，直徑影響於本研究設定之範圍內較不明顯；而烘乾處理則對雙剪行為的力學反應較對角壓縮行為具顯著影響。由於對角壓縮試驗機制仍存機械限制，導致試體受力行為複雜，未能完全呈現實際構件中之剪力傳遞。因此本研究認為，未來仍有進一步探討木質緊固件於微觀剪力機制之研究空間，將有助於補充非膠合構件接合處力學行為之理解。

This study focuses on the micro-scale behaviour of wooden dowels under double shear and their in-plain shear performance in non-adhesive laminated wood components. The double shear specimens measured 120mm × 180mm × 140mm. Dowels made of Swietenia mahagoni and Shorea spp., about 19.85 mm and 20.0 mm in diameter, were embedded into laminated Cryptomeria japonica members in both dried and undried conditions. Double shear tests used a 5-ton universal machine with vertical loading, continuing until the load dropped to 70% of peak or visible damage occurred. Diagonal compression specimens measured 308 mm × 150mm × 308mm, with the same dowels inserted, rotated 45°, fixed in metal jigs, and loaded vertically using a 20-ton machine. Load data and failure modes were recorded similarly.
This study compared the mechanical behaviour of Shorea spp. and Swietenia mahagoni wooden dowels. Shorea spp. generally demonstrated higher ultimate strength and ductility, making it more suitable for structural use, while Swietenia mahagoni, despite slightly higher yield strength in the linear range, failed in a brittle manner with lower toughness and unpredictable behaviour. In terms of dowel diameter, although 20.00 mm dowels were expected to be slightly stronger than 19.85 mm dowels due to a tighter fit, results showed slightly lower ultimate strength (by 2.1% and 6.8% for undried and dried conditions). Drying increased Shorea spp. yield strength by 1.31 and 9.5%, decreased its ultimate strength by 5.9 and 1.1%, and increased Swietenia mahagoni yield strength by 3.35% while slightly raising its ultimate strength by 1.5%. Drying significantly increased stiffness across all samples but ductility did not display a regular trend.
The specimens' yield strength was close to Eurocode 5 predictions, and ultimate strength exceeded theoretical values, with Shorea spp. reaching 1.3 to 2 times higher. Shorea spp. mainly exhibited Mode III failure with good ductility, while Swietenia mahagoni showed brittle failure and unstable mechanical performance.
In comparison to double shear, theoretical strength of diagonal compression was estimated at 1.5 times of double shear ones, but Shorea spp. exceeded this range due to interlayer friction effects, while Swietenia mahagoni fell short, confirming its unsuitability for structural applications.
In summary, the shear behaviour and strength of the laminated assemblies were mainly influenced by dowel species and density, with diameter having a lesser effect. Drying had a more significant impact on double shear than diagonal compression. Due to testing constraints, diagonal compression results could not fully reflect actual shear behaviour, highlighting the need for further micro-scale studies of wooden fasteners in non-adhesive laminated assemblies.

[1] Beer, F. P., Johnston, E. R., Jr., DeWolf, J. T., & Mazurek, D. F. (2015). Mechanics of materials (7th ed.). McGraw-Hill Education. ISBN 978-0-07-339823-5
[2] Fu, H., Li, Z., Alhaddad, W., & He, M. (2024). Experimental evaluation and theoretical prediction of dowel type joints connecting laminated veneer lumber with wood dowels. Construction and Building Materials, 369, 130489. https://doi.org/10.1016/j.conbuildmat.2024.135248
[3] Hill, C. A. S., Altgen, M., & Rautkari, L. (2021). Thermal modification of wood—a review: chemical changes and hygroscopicity. Journal of Materials Science, 56(11), 6581–6614. https://doi.org/10.1007/s10853-020-05722-z
[4] Incerti, A., Tilocca, A. R., Ferretti, F., & Mazzotti, C. (2019). Influence of masonry texture on the shear strength of FRCM reinforced panels. In G. Milani, A. O. Addessi, & S. Pellegrino (Eds.), Structural analysis of historical constructions (pp. 1623–1631). Springer. https://doi.org/10.1007/978-3-319-99441-3_174
[5] O’Ceallaigh, C., Sikora, K., & Harte, A. M. (2018). The influence of panel lay-up on the characteristic bending and rolling shear strength of CLT. Buildings, 8(9), 114. https://doi.org/10.3390/buildings8090114
[6] Turesson, J. (2016). Diagonal compression of cross-laminated timber (Master’s thesis, Luleå University of Technology, Department of Engineering Sciences and Mathematics).
[7] Vilguts, A., Phillips, A. R., Jerves, R., Antonopoulos, C. A., & Griechen, D. (2024). Monotonic testing of single shear plane CLT to CLT joint with hardwood dowels. Journal of Building Engineering, 88, Article 109252. https://doi.org/10.1016/j.jobe.2024.109252
[8] ASTM International. (1997). ASTM D5764-97a: Standard test method for evaluating dowel-bearing strength of wood and wood-based products. West Conshohocken, PA: ASTM International.
[9] ASTM International. (2022). ASTM E519/E519M-22: Standard test method for diagonal tension (shear) in masonry assemblages. West Conshohocken, PA: ASTM International.
[10] CIB-W18. (2006). Possible Canadian / ISO approach to deriving design values from test data (CIB-W18 No. 39). International Council for Research and Innovation in Building and Construction.
[11] European Committee for Standardization. (2002). EN 12512: Timber structures – Test methods – Cyclic testing of joints made with mechanical fasteners. Brussels, Belgium: CEN.
[12] European Committee for Standardization. (2004). EN 1995-1-1:2004+A1: Eurocode 5 – Design of timber structures – Part 1-1: General – Common rules and rules for buildings. Brussels, Belgium: CEN.
[13] European Committee for Standardization. (2007). EN 383: Timber structures – Test methods – Determination of embedment strength and foundation values for dowel type fasteners. Brussels, Belgium: CEN.
[14] European Committee for Standardization. (2009). EN 409: Timber structures – Test methods – Determination of the yield moment of dowel type fasteners. Brussels, Belgium: CEN.
[15] 林季木（2004）。木材真空微波加熱乾燥技術研究（碩士論文）。國立臺北科技大學冷凍與低溫科技研究所。
[16] 卓志隆、陳志昇（2014）。熱處理對三種國產人工林木材力學性質之影響。國立宜蘭大學森林暨自然資源學系。
[17] 趙盈婷（2020）。橫貫緊固件材質與角度對國產柳杉非膠合集成梁靜曲行為的影響（碩士論文）。國立成功大學建築研究所。
[18] 陳宣諭（2024）。非膠合木質緊固件集成牆體之側推行為與複合效益解析（碩士論文）。國立成功大學建築研究所。
[19] 中華民國國家標準（2013a）。CNS 450 木材之物理與強度試驗之取樣方法與一般要求【Wood - Sampling methods and general requirements for physical mechanical tests】。經濟部標準檢驗局。
[20] 中華民國國家標準（2013b）。CNS 452 木材含水率試驗法【Wood - Determination of moisture content for physical and mechanical tests】。經濟部標準檢驗局。
[21] 中華民國國家標準（2013c）。CNS 454 木材抗彎試驗法【Wood - Determination of static bending properties】。經濟部標準檢驗局。