柳杉造林木釘接組合之屋頂木桁架載重性能評估

Evaluation on the Loading Capacities of Wood Roof Truss Assembled with ＂Cryptomeria japonica＂ Plantation Timber by Nailed Joint

葉民權(Min-Chyuan Yeh) ； 林玉麗(Yu-Li Lin) ； 劉彥廷(Yen-Ting Liu) ； 余威論(Wei-Luen Yui)

《林產工業》 28卷2期 (2009/06) Pp. 113-124

摘要

本研究利用打音頻譜分析進行柳杉造林木結構用製材品之分等，並以適當等級作為屋頂木桁架之各部位構材，利用合板釘接板組合成跨距5m之木桁架，並進行抗彎試驗。結果顯示，抗彎承載力方面以45×120mm之構材斷面尺寸組合條件高於45×90mm條件29.1%，同時，哈威式木桁架高於芬克式木桁架11.2%；抗彎剛性方面構材尺寸45×120mm條件高於45×90mm條件13%，而哈威式木桁架亦高於芬克式木桁架12.5%。在設計載重條件下所開發之柳杉屋頂木桁架，其實測彎曲變位量僅為容許值之4.06~6.88%，同時，在規範設計變位限制條件下，柳杉木桁架之等效均布載重可達設計載重之7~9倍，在實質上具有相當之安全性。

關鍵字

柳杉 ； 木桁架 ； 抗彎性質 ； 釘接板

並列摘要

The structural sawn lumbers of ＂Cryptomeria japonica＂ (Japanese cedar) were graded using a tap tone approach and assigned as the proper members in the truss system. The 5-meter long wood roof truss with plywood nailing plates was subjected to a static bending test. Results indicated that the flexural loading capacity of the truss using 45×120mm members was 29.1% higher than that of 45×90mm members. The flexural loading capacity of Howe roof truss was 11.2% higher than that of Fink roof truss. The bending stiffness of the truss assembled with the 45×120mm members was 13.0% higher than that of 45×90mm members. The bending stiffness of the Howe roof truss was 12.5% higher than that of Fink roof truss. The measured flexural deflections of developed wood roof trusses were among 4.06~6.88% of allowable values under the design loads. It also showed that the equivalent distributed loading capacities of the Japanese cedar roof truss under the flexural deflection limitation specified in the Code were 7~9 times greater than those of the design loads, which assured the safety of developed truss in service.

並列關鍵字

Japanese cedar ； Wood truss ； Bending strength ； Nailing plate