運用應力波非破壞檢測方法研判健全臺灣傳統穿斗式木接點形式之研究

Examining Types of Timber Joints in Traditional Chuan-Dou Timber Frame by Stress Wave Method

隨著國內古蹟及傳統建築修復調查的大量需求，在這些古蹟及歷史建築中，穿斗式木構架佔相當大的比例。國內至今尚無法判斷穿斗式木構架接點的形式，因此本研究擬利用非破壞檢測方式提出研判穿斗式木構架接點形式的流程與方法。本研究中首先製作了72組3類不同形式的木接點，並利用應力波非破壞檢測儀器量測穿材上柱材兩端的應力波速及振動時歷資料。分析不同形式木接點的應力波速及振幅傳遞率，利用統計方式歸納出不同形式接點其應力波速及振幅傳遞率的範圍。在獲得結論後，另外製作9組試體做為確認實驗的依據，在經過確認實驗後發現前面試驗的分析其研究結果與確認試驗相互吻合。在經過分析後發現，對於穿材為連續、斷開對接及燕尾榫搭接等三類的平均波速分別為5276.44m/s、2688.33m/s、2670.14m/s；振幅傳遞率則分別為0.356、0.084、0.345。因此未來利用非破壞檢測研判木接點形式之流程應先利用波速研判穿材是否為連續或斷開。若為斷開則有斷開對接及燕尾榫搭接兩種可能性，此時應再利用振幅傳遞率針對穿材形式加以研判，利用概率密度函數分別計算斷開對接與燕尾榫搭接形式的可能性後加以研判。

Many traditional Chuan-Dou frame historic buildings exist in Taiwan. In-situ dismantling investigations indicated that three types of timber joints are involved in the traditional Chuan-Dou timber frames, which cannot be identified visually before dismantling. This research, therefore, aim at establishing a nondestructive testing (NDT) method to examine different types of timber joints in traditional Chuan-Dou timber frame. Firstly, 72 full-scale specimens were manufactured; stress wave method was used, and stress wave velocity and amplitude transmission ratio (ATR) were calculated. Thirdly, statistics analyses were carried out and the examination procedure was established. Lastly, 9 specimens were made for confirmation of experiments, and good agreement was found between the analyzed results and confirmation experiments. After analyses, the examination procedure proposed in this research is that stress wave velocity should be firstly measured to analyze the continuity of the beam elements. If the beam elements are diagnosed as discontinued, the amplitude transmission ratio should be calculated to examine the typologies of timber joints.