台灣傳統建築直榫木接頭補強之力學行為

Mechanical Behavior of Retrofitted Taiwan Traditional Tenon and Mortise Wood Joints

廖偉發(Wei-Fa Liao)

指導教授 ： 林至聰

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2007年)

https://doi.org/10.6841/NTUT.2007.00166

摘要

直榫接頭是台灣傳統建築構架中最常見的類型之ㄧ，此種榫接建築具有高韌強，低強度之結構特性，因此在重大側向力作用時，使結構物傾斜倒塌，造成若干重要文化資產嚴重的損失。本研究延續去年對直榫接頭力學行為之研究成果，並結合實際修復工法之考量下，針對直榫接頭之結構弱點，進一步提出補強措施，並探討各種不同補強措施之效果。
研究結果發現榫長越長則彎矩強度與旋轉勁度也越高，但直榫接頭所發展之最大彎矩強度僅為樑斷面的8.2%，顯示直榫木接頭之彎矩強度低，因此本研究配合文資法之規定，提出「可逆性」之補強工法，補強著重在提升直榫接頭之力學行為，在插銷補強方面，採用一根插銷補強效果較佳，原因為柱材之撕裂破情形較不嚴重，因此往後補強之設計應恰當，且同時須考量柱樑之容許強度設計。在圍束補強方面，採用藤箍補強，雖為其原生材料，但由於藤箍之勁度不如鋼索高，且藤箍無法如鋼索將樑柱接頭牢牢綑緊，所以鋼索補強之彎矩強度優於藤箍補強。在螺栓補強方面，一般墊片及螺帽均會造成木材承壓變形，使墊片沉陷，以致螺栓無法發揮其設計的抗拉能力，而本研究所提出的錐型墊片及矩形鐵塊將可有效改善木材局部沉陷之現象，並使彎矩強度提升。
由以實驗結果可知，所有補強試體之彎矩強度及旋轉勁度均有提升，顯示本研究提出的補強方案均有不同程度的補強效果，且符合文資法之規定， 保存原有色彩及形貌，增加其抗震之能力，並可將補強後之試體拆解，符合「可逆性」補強工法之需求。

關鍵字

大木構架 ； 榫卯 ； 旋轉勁度

並列摘要

Tenon-and-mortise joint is one of most common types of traditional Taiwan building structure, this kind of joint building has high tenacity and low strength structural characteristics. Therefore, under great lateral force, the structure inclines and collapses, leading to severe losses of some important culture heritages. This study continued research result of tenon-and-mortise joint mechanical behavior last year, considered actual repair skill, further proposed reinforcement measures against structural weak points of tenon-and-mortise joint, and discussed effects of various different reinforcement measures.
Research result showed that the longer the tenon, the higher the bending moment strength and rotational stiffness, but maximum bending moment strength developed from tenon-and-mortise joint was only 8.2% of beam section, indicating low bending moment strength of tenon-and-mortise joint, thus, this study responded to Culture Heritages Preservation Law, proposed “reverse” reinforcement method, concentrating on improving mechanical behavior of tenon-and-mortise joint, in regard to pin reinforcement, one pin had better result, for column tear was not so worse, thus later reinforcement design should properly and simultaneously consider design of allowable column strength. In regard to confining reinforcement, rattan bands were employed, which were natural material, but the stiffness was not so high as steel rope, and rattan bands failed to bundle beam column joint so tightly as steel rope, thus bending moment strength of steel rope reinforcement was better than rattan band reinforcement. As to screw reinforcement, ordinary gaskets and nuts would deform wood under compression and caused gasket depression, so that screws failed to play its role of designed tensile strength, while conical gaskets and rectangular iron block proposed in this study could effectively improve local depression of wood, and increase bending moment strength.
From test result, bending moment strength and rotational stiffness of all test specimens of reinforcement experiment increased, indicating that all reinforcement schemes proposed in this study had reinforcement effect to varied extent, and complied with Culture Heritage Preservation Law, kept original color and appearance, enhanced earthquake resistance, and reinforced test specimen could be disassembled, meeting demand of “reverse” reinforcement method.

並列關鍵字

wood structure, ； tenon and mortise ； moment ； rotational stiffness

參考文獻

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