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題 名 | 省產闊葉樹結構材容許應力設計值之建立探討=Investigation on Establishing Allowable Strength Properties for Domestic Structural Hardwood Lumber |
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作 者 | 葉民權; 林建宗; 蘇裕翔; 魏振財; | 書刊名 | 中華林學季刊 |
卷 期 | 30:1=116 1997.03[民86.03] |
頁 次 | 頁15-32 |
分類號 | 436.18 |
關鍵詞 | 容許應力; 分等; 木材機械性質; Allowable stress; Grades; Mechanical properties of wood; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究之目的在發展一套省產闊葉樹結構用木材之強度設計值,期望能拓展種類豐富的闊葉樹在木結構的應用,並與現行設計規範作一比較。研究中係依樹木分類及統計聚類分析將樹種合併,再依據 ASTM 標準中所規範結構用材之容許應力建立程序作為主體架構,利用標準試材之機械性質數值,經過適當之分等及各項修正因子的調整,以電腦算計算而得各類木材的強度設計值。本研究將省產闊葉樹六十八種依強度歸納為九類,每類再區分為結構輕框架、結構托樑與板材、樑與縱桁、柱與角材等四種用途別,各用途別又區分為一等材與二等材。所建議之無缺點木材強度值,以相思樹類、烏心石類、櫸木類、及櫧櫟類較優,而臺灣赤楊類及麻六甲合歡類最差。最後各項強度設計值調降幅度以二等材為最大,其中以拉伸強度調降最大,剪斷強度及靜曲強度次之,彈性係數為最小。與現行設計規範比較時,所推導之靜曲強度值較能依結構材用途別顯示強度值的差異,而平行木理壓縮強度設計值則較闊II類木材為低。所推導之彈性係數設計值以櫧櫟類、櫸木類、烏心石類為最優,麻六甲合歡類為最低。所推導的剪斷強度設計值因樹種類別不同差異頗大,而闊II類木材之數值均介於中間,故全理之分類應用有適材適用的效果。所推導之垂直木之數均介於中間,故合理之分類應具有適材適用的效果。所推導之垂直木理壓縮強度設計值則較闊II類木材數值為高,同時也能顯示不同樹種類別之強度差異,在木材利用上較具彈性且較為合理。 |
英文摘要 | The purpose of the study is to develop an allowable design properties system for structural lumber of hardwood species grown in Taiwan. The rocedures for establishing allowable stress are mainly according to ASTM Standards. There are nine established groups of species combinations, based on market practices and the results of cluster analysis. The design values were constructed from standard testing specimens after the lumber grading system was established based on mechanical properties data. Each species combination is then divided into four types of usage: structural light framing, structural joist and plank, beams and stringers, posts and timber, which in turn are classified into No.1 and No.2 grades for each type. It is noted that the Taiwan acacia, Formosan mechelia, Zelkova, and Chinkapin/Tanoak/Oak groups show higher values in clear wood strength properties, while the Formosan alder and Malacca albizzia groups show lower values. The derived design values for tensile strength show the greatest reduction from the clear wood strength, following by shear strength and bending strength, while the modulus of elasticity design values have the least reduction. Furthermore, No.2 grade lumber shows higher reduction in design values than that of No.1 grade lumber. Comparing to the current specification, the derived bending strength design values can be more flexible based on usage classification of lumber. On the other hand, both the compression strength and the tensile strength design values are lower than type II lumber assigned in the current specification.The higher design values of modulus of elasticity can be found among the species combinations of Chinkapin/tanoak/Oak, Zelkova, and Formosan michelia, while the lower values can be found in the Malacca albizzia group. the derived shear strength design values which vary with the species combinations indicate that better utilization of lumber can be achieved by reasonable species classification. The design values of compression strength in the direction perpendicular to the grain are higher than that of listed for type II lumber in current specification, and also vary with species combinations. |
本系統中英文摘要資訊取自各篇刊載內容。