本研究以國產福杉作為研究對象，探討使用預製金屬件接合的木構造柱梁接點的旋轉行為，並透過自攻螺絲補強，比較補強前後及不同型號的預製金屬接合件在結構性能上的差異。預製金屬件不僅具有足夠的剪力強度，施工便利及高精確度更是此構法具高競爭力和未來發展潛力的原因。本研究使用的預製金屬件規格為40 x 90 mm，厚度12mm，木材試體部分使用斷面120 x 120 mm實木柱及斷面120 x 180mm的膠合集成梁，並選用直徑8mm的全牙自攻螺絲作為補強材。
旋轉試驗根據實驗參數分為四組:無補強(None reinforcement，Nr)、預補強30度(Pre-reinforcement 30°，Pr30)、預補強45度(Pre-reinforcement 45°，Pr45)及後補強45度(Repair reinforcement 45°，Rr45)。其中，無補強組單純測試接合件的抗彎性能並作為對照組；預補強組比較一對自攻螺絲以不同鎖入角度鎖入對補強效益之影響；後補強組則是在無補強組實驗至破壞後，以45度進行補強修復。接著藉由足尺的旋轉試驗取得接點的極限彎矩、降伏彎矩、旋轉勁度和破壞模式，評估接合件的抗彎性能並透過分析實驗數據及等式推導探討不同補強模式對於結構性能的效益。
實驗結果顯示:預補強30度(Pr30)、預補強45度(Pr45)的極限彎矩分別較無補強(Nr)提升了44.4%和40%；旋轉勁度則提升了39.1%和28.6%；而後補強45度(Rr45)的極限彎矩雖也較無補強組提升了28.9%，但旋轉勁度方面降低了56%，以此判斷為因木料本身纖維遭破壞而難以回復原有對螺絲之握裹力外，接點的極限彎矩及降伏彎矩均因自攻螺絲的補強而獲得提升。預補強45度(Pr45)及後補強45度(Rr45)除在旋轉勁度之差異外，兩者的極限彎矩非常接近，僅相差2.3%，說明以同角度補強能獲得相同之效益；而比較不同角度的補強方式，預補強30度(Pr30)的極限彎矩及旋轉勁度分別略高於預補強45度(Pr45)4.4%和10.5%。比較不同規格接合件的實驗結果，同樣進行螺絲補強之接點，使用SHERPA S20鐵件之接點在極限抗彎和旋轉勁度分別約為使用S15鐵件之接點的1.16~1.2倍和1.5~2倍。未螺絲補強之試體(Nr)在極限強度上無明顯差異，但在勁度表現上卻相差將近兩倍，推測是因鐵件長度及鎖固之自攻螺絲增加使其在勁度上有如此差異。
本研究的實驗結果可作為未來接合件開發及優化方式之參考，除接合件設計成細長型以利補強間距外，在梁端鐵件使用較柱端長的鎖固螺絲以彌補平行纖維方向鎖入導致強度較弱之問題，更需考量公母鐵件之緊固機制已排除預期外之破壞模式發生。

The paper is focused on the rotational behaviour of beam-to-column timber joint with prefabricated metallic connector and use self-tapping screws to enhance its structural performance. The advantages of prefabricated metallic connectors are precise, simple and fast for assembling during construction. This research used solid timber columns, whose size is 120×120×900 mm, and 120×180×1200 mm glulam beams, which are made of two pieces of solid timber with a thickness of 900mm. Both beam and column are made by Cunninghamia lanceolata. The self-tapping screw (STS) is made by local manufacturers in Taiwan.

The experiments consist of four groups of timber joints with different configurations: [I] None reinforcement (Nr) as a control group; [II] Pre-reinforcement in 30 degrees (Pr30); [III] Pre-reinforcement in 45 degrees, which is drilled with a pair of STSs at a different angle before the experiment started; [IV] Repair-reinforcement in 45 degrees (Rr45), which is drilled by the STS at 45 degrees after group Nr loaded to failure. The experiments of beam-to-column joints use full-scale tests to evaluate rotational behaviour, including maximum bending moment, yielding bending moment and rotational stiffness.

The experiment results indicate that the application of STS reinforcements can effectively enhance the performance of beam-to-column joints. Overall, the moment-resisting capacities of group Pr30, Pr45 and Rr45 are 44.4%, 40% and 28.9% higher than group Nr, respectively. The performance of beam-to-column joints was mainly influenced by the angle of STS. The value of maximum moment-resisting capacities of group Pr30 is 4.4% higher than group Pr45. Group Pr30 and group Pr45 have similar moment-resisting capacities. Meanwhile, the rotational stiffness can be improved except group Rr45. It is presumed that the screw’s withdrawal resistance cannot be repaired because the grain of the timber itself has already failed.

This study shows that either pre-reinforcement or repair-reinforcement is beneficial to the performance of timber joints. The results of this study can be used as a reference for future research and optimisation of timber beam-to-column joints.

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