Development of Roof Trusses with Metal Plate Connectors Using Domestic Plantation Timber

本研究開發三種刺鐵板聯結件，並應用於屋頂桁架之組合，進一步評估所組成之柳杉屋頂桁架之結構性能。所開發之刺鐵板聯結件採用SS33結構用鋼材質，齒長為9 mm，齒密度為每平方公分1齒，鐵板厚為0.9 mm。柳杉材經刺鐵板聯結件組合後，在引張條件下測定，所設計之刺鐵板聯結件的載重能力為每齒216~265 N，同時，經推導後所得之容許抵抗值為每齒68.3~86.4 N。以38×140 mm構材所組成屋頂木桁架系統之最大抗彎載重值及抗彎剛性，分別高於38×89 mm條件者82.6及48.9%，而哈威式與芬克式桁架之間則無顯著之差別。柳杉屋頂桁架在抗彎過程中，其破壞關鍵位置在上下弦桿接合處；在構材尺寸為38×140 mm條件下，桁架有75%是屬於齒引拔及板剪斷之破壞，在38×89 mm條件下，有87.5%是屬於齒引拔破壞。柳杉屋頂桁架在設計載重條件下測定之抗彎變位為設計限制之5.0~20.5%，而屋頂之設計載重亦僅為桁架破壞時之極限等效均布載重之9.9~18.9%，故在實際應用上具有相當之安全性。

關鍵字

屋頂木桁架；刺鐵板聯結件；抗彎性質；柳杉

並列摘要

Metal plate connectors (MPCs) were developed and applied to truss assemblies to evaluate the structural performance of Japanese cedar roof trusses in the study. An MPC with a tooth length of 9 mm, a plate thickness of 0.9 mm, and a tooth density of 1 tooth cm^(-2) was designed and produced using SS33 structural steel sheets. The loading capacities of the designed MPC were 216~265 N per tooth, and the derived allowable lateral resistance was 68.3~86.4 N per tooth for Japanese cedar lumber joints in tension. Ultimate bending capacities and stiffness of the 38×140-mm wood roof truss system were 82.6 and 48.9% higher than those of 38×89-mm wood roof truss, respectively. No significant difference was found between Howe and Fink trusses. The critical failures in Japanese cedar roof trusses were located at the heel joint, and these accounted for 75% due to a combination of tooth withdrawal and plate failure in the 38×140-mm truss, and 87.5% due to the tooth withdrawal in the 38×89-mm truss. Flexural deflections of Japanese cedar roof trusses measured at the design load level were within 5.0~20.5% of the design deflection limitation. Furthermore, the designed roof load was only 9.9~18.9% of the ultimate equivalent distributed loads measured at truss rupture, which assures the safety of Japanese cedar roof trusses in service.

並列關鍵字

wood roof truss ； metal plate connector ； flexural property ； Japanese cedar

國際替代計量

Development of Roof Trusses with Metal Plate Connectors Using Domestic Plantation Timber

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