柳杉造林木建造集成材拱橋之抗彎性能評估

Flexural Properties of GIuIam Arch Bridge Using Japanese Cedar Plantation Timber

葉民權(Min-Chyuan Yeh) ； 林玉麗(Yu-Li Lin) ； 蕭英倫(Ing-Luen Shiau)

《林產工業》 25卷4期 (2006/12) Pp. 283-294

摘要

本研究之目的在探討國產柳杉造林木應用于結構用彎曲集成材之製造以及建這成拱橋之彎曲承載性能，實驗中以12支3600×100×21mm之集成元集成，以自行設計H型扣件接合成曲率為π/6，5930mm長之彎曲集成材，集成元之配輩分為2種形式，評估在端部滑動限制條件下之靜力抗彎性質。結果顯示拱構材之複合彎曲應力為874kgf/cm^2，抗彎剛性為460×10kgf/cm遠高於標準E170-F495集成材簡支直樑之預期性能，同時也僅有輕微之半徑方向應力，其中拱梁上方呈徑向拉伸，為下方呈徑向壓縮之2.24倍。拱橋依規範建造，依設計活載重探討其承載性能，評估橋梁之潛變與耐久性。所建造之5930mm長彎曲集成拱橋之預期最大破壞承重為22434kgf，于設計活載重二個月的期間，其潛變速率即呈穩定階段，且達三個月總變位量之93.9%，彎曲集成材拱橋長期變位則相當於跨距長的1/494，優於標準規定的1/300高出1.65倍。集成材拱橋歷經18個月長期暴露室外天候條件下，外表並無腐朽、白蟻、蛀蟲、變色現象發生，塗裝效果亦完好。

關鍵字

木造橋 ； 彎曲集成材 ； 抗彎性質 ； 柳杉

並列摘要

Flexural properties of both curved structural glulam members and arch bridge constructed with domestic Japanese cedar plantation timber were investigated in the study. The curved glulam member was laminated by using twelve pieces of 3600×100×21mm laminae and each curved member specimen was assembled by a H type steel fastener between the ends of two glulam members forming a curvature of π/6 with a length of 5930mm. The static flexural properties of glulam arch specimens with two types of lamina arrangement were evaluated under the condition of slip restrained at both end supports. The results indicated that the combined bending stress of the arch member is 874kgf/cm^2 and the bending stiffness is 460×103kgf/cm^2, which are superior to the structural performance of standard E170-F495 streight glulam beams as specified in the Code. A small radial was also produced at the center of the arch member which showed tension on upper side of cross section, about 2.24 times the compression on lower side of cross section. The expected maximum loads at failure of 5930mm arch bridge is 22434kgf. The flexural creep deformation of the bridge subjected to two-month design live loads reached into a steady stage, 93.9% of a three-month creep deformation. This long-term flexural deflection is 1/494 of the bridge span, 1.65 times the design limitation of 1/300 of the span. The glulam arch bridge showed no deteriorations such as decays and molds, termite and insect attacks, and discolorings after 18-monthsexposure to the weather and the coatings were also in a good condition.

並列關鍵字

Wood bridge ； Curved glulam ； Static bending properties ； Japanese cedar