杉木製造工字樑及其靜曲效能之研究

Flexural Performance of I-beam Fabricated from ＂Cunninghamia lanceolata var. lanceolata＂

張桂英(Kuei-Ying Chang) ； 葉民權(Min-Chyuan Yeh)

《林產工業》 20卷3期 (2001/09) Pp. 195-205

摘要

工程木材在木質結構上為重要之工程材料，本研究為提高木材有效率利用，並拓展省產材之應用而進行木質工字樑之聞發，在試驗中採用杉木進行實大尺寸工字樑之組合，並進行樑靜曲性能之評估，同時考慮在樓板托樑應用之可行性。試驗因子包括不同樑翼寬和用釘問距及使用環氧樹脂膠合劑補強等組合條件，對杉木工字棵之靜曲強度的影響。工字樑深度為30 cm長度為3.6 m，測試方法採用ASTM D198-94之四點載重靜曲試驗。同時依據中國國家標準有關無缺點試材之試驗方法評估杉木構材機械性質。試驗結果顯示杉木工字樑在靜曲載重破壞時之模式，主要是自木材缺點處或是剪力抵抗較弱的位置開始劈裂。其破壞模式可進一步歸納成五大類。在樑破壞時之最大靜曲載重能力方面，使用8 cm、10 cm、12 cm等不同釘距之間無明顯區別，以環氧樹脂膠合劑補強則提高41%。杉木工字樑破壞時之彎曲應力在未加膠合劑條件下，樑翼材分別為2×4和2×6者較2×8之試材高出76%及17%；在環氧樹脂膠合劑補強條件下，樑翼寬分別為2×4和2×6者較2×8之試材高出85%及43%。同時2×6及2×8工字樑之靜曲彈性係數分別為2×4者之68%及56%。2×4、2×6、2×8等不同寬幅於一般0.6 m間距施工條件下，釘接杉木工字樑所能承載之均佈載重，較技術規範所容許使用之最大載重限制分別高出1.65倍，1.52倍及1.50倍，而使用膠合劑補強之工字樑則分別可提高2.55倍，3.59倍和3.71倍，在樑設計載重下之變位量加膠合劑者僅為未加膠合劑者所產生之彎曲變位量的63%，且僅及規範之變位限制的12.9%。故本研究所探討之杉木工字樑靜曲效能可滿足木質構造樓板托樑之設計需求。

關鍵字

杉木 ； 工字樑 ； 靜曲性能 ； 四點載重

並列摘要

Chinafir (Cunninghamia lanceolata var.lanceolata) is used as materials for the assembly of I-beams. The width of flanges includes 2×4, 2×6, and 2×8. The flanges and webs were assembled with 16d box nails in nail spacing of 8 cm, 10 cm, and 12 cm, respectively. The effects of epoxy glue application between flanges and webs on the flexural performance of l-beams were also investigated. l-beam with 3.6 m in length was subjected to four-pointloading for static flexural tests with a span/depthratio of 11.7. The static flexural tests were performed according to the methods specified in ASTM DI98-94. The mechanical properties of China fir solid wood were also evaluated based on CNS standards. The typical failure of l-beams subjected to flexural loading was splits along the grain of lumber due to weakness of shear resistance. The improvement on maximum loading capacity is 41% for I-beams reinforced by adhesive as compared to those fastened only with nails. Howere, no significant differences were found among the I-beam assembles with the nails spacings of 8 cm, 10 cm, and 12 cm, respectively. The f_b of I-beams with 2×4 and 2×6 flanges and assembled with nails were only about 76% and 17% higher than those with 2×8 flanges, respectively, while 85% and 43% higher could be found on those I-beams reinforced by epoxy adhesive. The maximum load capacities of nailed I-beams were about 1.65, 1.52, and 1.50 times of the loads allowed in the Code, respectively, and 2.55, 3.59, and 3.71 times for the I-beams reinforced by glues, respectively, as calculated based on 0.6 m spacing in joist arrangement.

並列關鍵字

China fir ； I-beam ； Flexural performance ； Four-point loading