Structural Strength of Student Desks and Chairs Made of Western Hemlock

西部鐵杉製課桌椅強度研究

周群(Chun Chou) ； 李銘鐘(Ming-Chung Lee) ； 黃清吟(Chin-Yin Hwang) ； 黃國雄(Gwo-Shyong Hwang)

《台灣林業科學》 15卷3期 (2000/09) Pp. 317-335

https://doi.org/10.7075/TJFS.200009.0317

摘要

本研究利用加拿大進口之西部鐵杉，探討材料陸質及其製作課桌椅之適宜性。結果顯示等級愈高之板材有愈好之利用率，且板材厚度對利用率影響最大。西部鐵杉小試片之強度測試顯示，強度隨比重增加而加強，但與板材之品等無關。課桌椅之構件比重只影響對置物空間下層合板之測試，與其餘之結構強度無關。在反覆衝擊試驗下，所有課椅均未達標準，在椅後腳與椅座下檔接合處發生接合鬆脫情形；但在未限制椅後腳移動之條件下，有40%通過測試。使用環氧樹脂之165型新式課桌，為唯一通過反覆衝擊試驗者。所有課桌均通過垂直荷重試驗。在穩定性測試中，新型課桌表現優於舊型。課桌置物空間之橫檔，需使用較佳強度之鐵杉。

關鍵字

課桌椅 ； 西部鐵杉 ； 材料強度 ； 結構強度

並列摘要

The strength properties of western hemlock (Tsuga heterophylla) lumber, imported from British Columbia, Canada, were evaluated, and the feasibility of utilizing it for making student desks and chairs was investigated. Results indicated better grade lumber resulted in a better recovery in manufacturing desks and chairs, with lumber thickness being the most influential factor in determining the recovery value. Regardless of lumber grade, material strength properties of small clear western hemlock specimens increased with an increase in density. The structural strength of desks and chairs was not affected by their component density except in the bottom plate of the storage space of desks which was tested by repetitive impact. No 8(superscript th)-grade chairs passed the repetitive impact tests, as specified in the JIS-S1021 standard which requires that the back legs be hinged to the ground, and failures occurred at joints between the side rails under the seat and back legs. However, 2 out of five 8(superscript th) grade chairs passed the modified repetitive impact tests when the restraining metal hinges were removed. Type-165 desks assembled with epoxy passed the repetitive impact test. Both types of desks passed the vertical loading tests, and Type-165 desks showed greater structural stability than did the 8(superscript th)-grade type. Using high-strength rails for supporting the bottom plywood plate in the storage space of desks is recommended. Further studies should be focused on improving the structural performance of desks and chairs to be used by primary and junior high school students in Taiwan.

並列關鍵字

student desk and chair ； western hemlock ； material strength ； structural strength