以臺灣櫸作為柳杉結構材之裝飾補強材料探討

Abstract

本研究利用小尺寸之臺灣櫸(Zelkova serrata)作為柳杉(Cryptomeria japonica)集成樑結構用材之裝飾補強材之探討。試材先以應力波法及抗彎彈性模數試驗評估集成元狀況，並計算出集成樑之抗彎彈性模數預測值(Ebp)，再依據抗彎彈性模數預測值進行集成樑之配置膠合，後針對集成樑進行抗彎強度性質、膠合剪斷性質、剝離性質之分析與評估；另外再針對集成樑之強度相關性質進行分析外，亦依據補強斷面積分析補強成本效益。 實驗先以集成元抗彎彈性模數(Modulus of elasticity, MOE)，進行強度配置，再利用彎曲剛性(Bending stiffness, EI)相等之原則，計算配置後之集成樑之Ebp，並與抗彎彈性模數真實值(Ebr)做相關性分析。理論上Ebr與Ebp應要能成正相關，然若不分組之Ebp及Ebr兩者進行相關性分析，結果指出其R²僅有為0.33，顯示相關性不如預期，推測為補強方式及補強面積會影響其推估兩數值之公式係數，然組別依貼合補強及鑲嵌補強分組分析後可發現Ebp及Ebr兩者相關性可大幅提升，除G5組(以寬15 mm 之臺灣櫸貼合補強於柳杉上下側)及G6組(以寬10 mm 之臺灣櫸貼合補強於柳杉上下側)之R²未達0.50外，其餘皆高於0.50，其中又以G8組(以寬10 mm 之臺灣櫸鑲嵌補強於柳杉上側)之R²為最佳(0.93)，顯示預測值具有參考價值，可達到預測效果。 根據抗彎試驗結果可知，若僅考慮抗彎強度(Modulus of rupture, MOR)時，以G4組之以寬20 mm之臺灣櫸貼合補強於柳杉上下側及G10組之以寬15 mm 之臺灣櫸鑲嵌補強於柳杉上下側者，有顯著之強度提升，而若只考慮Ebr時，G1 組之以寬20 mm 之臺灣櫸貼合補強於柳杉上側者、G2組之以寬15 mm 之臺灣櫸貼合補強於柳杉上側者、G5組之以寬15 mm 之臺灣櫸貼合補強於柳杉上下側者、G6組之以寬10 mm 之臺灣櫸貼合補強於柳杉上下側者及G10組之以寬15 mm 之臺灣櫸鑲嵌補強於柳杉上下側者皆相對於對照組，有顯著提升其Ebr值，因此綜合兩者可發現G10組之以寬15 mm 之臺灣櫸鑲嵌補強於柳杉上下側者可同時獲得顯著之Ebr與MOR值，Ebr值為12.1 GPa，較柳杉對照組提升了24.7%，MOR值為75.5 MPa，較柳杉對照組提升了20.2%。

This study is discussed using the small-scaled Taiwan Zelkova (Zelkova serrata) as a decorative reinforcement for Japanese ceder (Cryptomeria japonica) beam structures. The material used the stress wave method and the flexural elastic modulus method to evaluate the condition of the integrated element and then calculated the predicted value of the flexural elastic modulus (Ebp). The glulam is configured according to the predicted value of the flexural elastic modulus. After gluing, we analyzed and evaluated the properties of bending test, gluing shear, and peeling of glulams. Also, based on the analysis of basic properties, we analyze the strength-related properties of glulams. To facilitate future practical applications, this research also compared the cost-effectiveness of reinforcement in different reinforce area. In the experiment, we configured the integrated element into the beam based on the Modulus of elasticity (MOE). And according to the principle of equal bending rigidity (EI) calculated the Ebp of the glulam, and compare it with the actual value of the flexural elastic modulus (Ebr) by correlation analysis. The results said that while analyzed without separating data into the group, Ebr will increase with the increment of Ebp, but its R² is only 0.33, which shows that the reinforcement method and reinforcement area will affect the values. Analyzed according to the groups, shows that the correlation between Ebp and Ebr can be greatly improved. Except for the G5 reinforced with a width of 15 mm with both sidesa nd the G6 group reinforced with a width of 10 mm on both side, in which R² is less than 0.50, the rest are higher than 0.50, the R² of the G8 group reinforced with 15 mm wide Taiwan Zelkova on the upside is the best (0.93), indicating that the predicted value could be a reference for the prediction. According to the flexural test results, considered the Modulus of rupture (MOR), the G4 group was reinforced with Taiwan Zelkova with a width of 20 mm on both sides of the Japanese ceder and the G10 group reinforced with Taiwan Zelkova with a width of 15 mm on both sides have significant increment. About Ebr, the G1 group reinforced with a 20 mm wide Taiwan Zelkova patch on the upside, the G2 group reinforced with 15 mm wide Taiwan Zelkova on the upside, the G5 group reinforced with a width of 15 mm with both sides, the G6 group reinforced with a width of 10 mm on both side, and the G10 group reinforced with 15 mm wide on both side, are significantly improved. Therefore, the G10 group has well improved in both Ebr and MOR values. The Ebr value is 12.1 GPa, which is 24.7% higher than that of the control group, and the MOR value is 75.5 MPa, which is 20.2% higher than the control group.