前台南市政府屋頂木桁架之強度性質

本研究以舊台南市政府屋頂木桁架為材料，在鑑定樹種後，利用非破壞性檢驗方法（應力波）測其動彈性係數及利用靜曲試驗測靜曲彈性係數和靜曲破壞係數，以了解桁架材料在多年使用後的殘餘強度和非破壞性方法預測靜曲性質的可行性。材料經鑑定計有六種針葉樹材（台灣扁柏、紅檜、鐵杉、台灣二葉松、華山松和台灣五葉松）和三種闊葉樹材（厚皮香、樟葉槭和長尾尖櫧）。靜曲性質包含靜曲彈性係數和靜曲破壞係數在多年使用後與參考值比較都有減少的現象，靜曲彈性係數較參考值小12～61%，而靜曲破壞強度小於參考值9～64%。除鐵杉外，應力波所測動彈性係數均大於靜曲彈性係數。其比值範圖為0.95～1.583。當以動彈性係數預測靜曲破壞係數時，其迴歸方程式僅有四種樹種具有意義。

關鍵字

桁架結構材；非破壞性試驗；破壞性試驗；強度保留率

並列摘要

The material taken from the roof of the former Tainan City Hall was identified, and then the dynamic modulus of elasticity (MOEd) was calculated using the stress wave method and the bending properties were obtained by static bending test. The bending properties were compared with those of the referenced values to understand the residual properties of the material after service. The dynamic property was correlated with the bending properties. The material used in the roof truss of the former Tainan City Hall included six softwoods (Taiwan yellow cypress, Taiwan red cypress, Chinese hemlock, Taiwan red pine, Armand pine, and Caudate-leaved chinkapin) , and three hardwoods (Japanese temstroemia, Flying moth tree and Castanopsis carlesii) . Both the MOEs and the MORs were less than the referenced values of the same wood species by 12-61% and by 9-64%, respectively. The MOEds were always higher than the MOEs with the ratioes ranging from 0.95 to 1.583. When MOEds were used to predict MORs, only four out of eleven cases (nine species and two deteriorated species) demonstrated significant regression lines.

並列關鍵字

Roof truss ； Nondestructive testing ； Destructive testing ； Residual strength ratio

國際替代計量

前台南市政府屋頂木桁架之強度性質

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