中小徑木製造構造用集成材及其工程性能之研究

Abstract

本研究乃針對集成元之配置與設計進行集成材製造，探討構造集成材之工程性能與火災性狀，以非破壞檢測技術評估省產之柳杉、台灣杉等中小徑木以及國外廣泛用於集成材之花旗松與南方松等集成元之抗彎性質，建立其強度相關性。首先，主要利用不同之目視分等方法（中國國家標準第14630號與第14631號）與超音波、橫向振動儀等非破壞檢測儀器評估集成元之材質，究明非破壞檢測法應用之可行性及其材質優劣與等級，並經有效之配置，達到構造用集成材之設計。次而依中國國家標準第11031號結構用集成材標準進行相關之抗彎強度、剪斷強度以及剝離性質等試驗，究明集成材之力學特性，並於進行強度試驗之同時，於集成材之中央側黏貼應變片，量測抗彎試驗時構成集成材之各個集成元之應變狀態，以究明不同配置下，不同位置之集成元在自由狀態及構成集成材狀態下，各個集成元之彈性模數，並依應力與應變之關係，求出集成材中立軸之位移改變狀態。最後，探討集成材於CNS 12514標準燃燒時間溫度曲線下，其炭化速度、構造內部溫度變化與構造用集成材經標準燃燒試驗後之力學性質。經上述之試驗結果指出，利用現行中國國家標準中，CNS 14630針葉樹結構用製材與CNS14631框組壁工法結構用製材兩種目視分等法進行集成元強度等級區分，在DMOEv值、DMOEt值與MOE值方面均可得結構材（一級材）＞標準材（二級材）＞普通材（三級材）之趨勢。在非破壞檢測法上，以橫向振動法之動彈性模數（DMOEt）評估集成元之抗彎彈性模數較佳，其R2達0.83-0.90。 利用EbI＝ 計算法進行集成元之配置與集成材強度之計算，集成材之抗彎彈性模數預測值（Eb(sp)）與抗彎彈性模數實測值（Eb(sc)）成顯著之正相關，其R2值為0.82-0.92。透過外層集成元之強度配置，集成材之抗彎彈性模數與抗彎強度均隨外層集成元之彈性模數之增加而有隨之增加之趨勢，其R2值分別為0.79-0.94與0.52-0.63。以振動法求得集成材之剪斷模數（G）值，其E/G比，柳杉、台灣杉、花旗松與南方松各集成材分別為13.2-14.5、14.4-16.6、12.1-16.6與16.0-19.1。而消除剪力撓曲影響，即可得集成材之抗彎彈性模數真實值（Ep）與抗彎強度（MOR），依本研究配置所得之柳杉集成材之Ep值與MOR值分別為10.6-13.4 GPa與48.3-61.9 MPa；台灣杉集成材之Ep值與MOR值分別為12.1-15.0 GPa與41.8-58.8 MPa；花旗松集成材之Ep值與MOR值分別為10.5-16.4 GPa與37.2-65.6 MPa；南方松集成材之Ep值與MOR值分別為14.5-20.6 GPa與70.2-78.4 MPa。利用應變片法所得之抗彎彈性模數（Eb(sg)與Eb(sa)值）與Ep值之間有顯著之正相關性存在，其R2值為0.70 - 0.96。 集成材之火災特性上，炭化速度方面：杉木集成梁側面之炭化速度為0.587 - 0.750 mm/min；底面之炭化速度為0.709 - 0.897 mm/min；柳杉集成梁側面之炭化速度為0.643 - 0.770 mm/min；底面之炭化速度為0.644 - 0.911 mm/min；台灣杉集成梁側面之炭化度為0.608 - 0.757 mm/min；底面之炭化速度為0.614 – 0.817 mm/min；花旗松集成梁側面之炭化速度為0.588 - 0.627 mm/min；底面之炭化速度為0.632 - 0.694 mm/min；南方松集成梁側面之炭化速度為0.530 - 0.568 mm/min；底面之炭化速度為0.566 - 0.583 mm/min，有南方松集成材優於花旗松集成材，依序為杉木集成材、柳杉集成材、台灣杉集成材之趨勢。而在集成材燃燒時之內部溫度分佈方面，省產之柳杉集成材與台灣杉集成材受熱時之內部溫度均有大於花旗松集成材與南方松集成材之趨勢。 經燃燒試驗後，集成材之力學性質上，集成材之抗彎強度會隨燃燒時間之增加而降低，其中，杉木集成材之MOE值由4.1 GPa降至2.5 - 3.8 GPa，MOR值由48.2 MPa降至27.1 - 36.6 MPa；柳杉集成材之MOE值由5.3 GPa降至3.7 - 4.6 GPa，MOR值由54.8 MPa降至23.0 - 39.4 MPa；台灣杉集成材之MOE值由5.3 GPa降至3.4 - 4.7 GPa，MOR值由51.4 MPa降至21.8 - 38.6 MPa；花旗松集成材之MOE值由7.7 GPa降至6.6 - 6.9 GPa，MOR值由62.7 MPa降至33.2 - 40.8 MPa；南方松集成材之MOE值由6.0 GPa降至4.4 - 5.3 GPa，MOR值由58.9 MPa降至26.4 - 42.1 MPa。但在剪斷強度與抗壓強度性質上，位於中央側之試片，其強度與未經燃燒試驗之集成材強度值間，並無顯著差異。

The purposes of this study was to investigate the effects of the configuration of the lamina on the engineering and fire performance of glulam made from Japanese cedar, Taiwania, Douglas-fir, and Southern pine lumber. First of all, two kinds of visually graded criterions, CNS 14630 and CNS14631, were applied to grade selected laminaes. Then, the bending properties of Japenses cedar, Taiwania, Douglas fir, and Southern pine laminaes were measured by nondestructive test methods including ultrasonic wave test, transverse vibration test, and static bending test. The relationships between two dynamic modulus of elasticity, DMOEv and DMOEt which were calculated respectively by ultrasonic wave test and transverse vibration test, and static modulus of elasticity were understood.In addition, in order to evaluate the properties of glulam, the bending properties, shear strength, and peeling properties were test according to CNS 11031. Moreover, the strain of each laminae was measured during the bending test by affixing the strain gauge at the central axis of edge face, then, the modulus of elasticity and the position of neutral axis of whole glulam were determined.Finally, the charring rate, temperature distribution inside the glulam and mechanical properties of glulam were measured after standard fire exposure test. These results were summarized as fallows: The DMOEv, DMOEt, and MOE values for all laminaes graded by visual graded criterions showed a decreasing order in construction grade (Class 1) ＞ standard grade (Class 2) ＞ utility grade (Class 3). There was also significant linear relationship between the values, DMOEt, DMOEv, and MOE. The highest R2 value was ranged from 0.83 to 0.93 for laminae between the DMOEt and MOE, and it was also found that the transverse vibration test is a better nondestructive method for lamina evaluation. Consider the existence of the glue layers, the bending stiffness of glulam EbI is the sum of laminas and glue layers bending stiffness (EbI＝ ). It was found that the Eb(sp) increased with the Eb(sc) increasing and the R2 values were ranged from 0.82 to 0.94. Furthermore, It was also found that the Eb(sc) and MOR values of glulam increased with the MOE of the outside layers of lamina increasing, and the R2 values were ranged from 0.79 to 0.94 and 0.52 to 0.63, respectively. Because the bending glulam was subjected to the both pure bending moment and vertical shear force, the actual deflection included shear deflection. Hence, the modulus of rigidity, G, of glulam was measured by vibration test method in order to realize the shear deflection effect. The E/G values of Japanese cedar, Taiwania, Douglas-fir, and southern pine glulam were ranged form 13.2 to 14.5, 14.6 to 16.6, 12.1 to 16.6 and 16.0 to 19.1, respectively. The pure MOE（Ep） was also obtained. The Ep and MOR values of glulam were ranged from 10.6 to 13.4 GPa and 48.3 to 61.9 MPa for Japanese cedar, ranged from 12.1 to 15.0 GPa and 41.8 to 58.8 MPa for Taiwania, ranged from 10.5 to 16.4 GPa and 37.2 to 65.6 MPa for Douglas-fir, ranged from 14.5 to 20.6 GPa and 70.2 to 78.48 MPa for Southern pine, respectively. Results also indicated that a positive linear correlation between modulus of elasticity measured by strain gauge method (Eb(sg) and Eb(sa)) and values of Ep, the R2 values were ranged from 0.70-0.96. In the fire performance study, the charring rate of side and bottom were ranged from 0.587 to 0.750 mm/min and 0.709 to 0.897 mm/min for China fir glulam, 0.643 to 0.770 mm/min and 0.644 to 0.911 mm/min for Japanese cedar glulam, 0.608 to 0.757 mm/min and 0.614 to 0.817 mm/min for Taiwania glualm, 0.588 to 0.627 mm/min and 0.632 to 0.694 mm/min for Douglas-fir glulam, and 0.530 to 0.568 mm/min and 0.566 to 0.583 mm/min for Southern pine glualm, respectively. The results indicated that the charring rate in all glulam showed a decreasing order in Taiwania＞Japanese cedar ＞China fir ＞Douglas-fir＞Southern pine glulam. The inside temperature of Japanese cedar and Taiwania glulam were higher than that of Douglas-fir and Southern pine glualm under the standard fire exposure test After standard fire exposure test, the bending properties of glulam decreased with the fire exposure time increasing. The values of MOE and MOR decreased respectively from 4.1 GPa to 2.5-3.8 GPa and 48.2 MPa to 27.1-36.6 MPa for China fir glulam, from 5.3 GPa to 3.7-4.6 GPa and 54.8 MPa to 23.0-39.4 MPa for Japanese cedar glulam, from 5.3 GPa to 3.4-4.7 GPa and 51.4 MPa to 21.8-38.6 MPa for Taiwania glulam, from 7.7 GPa to 6.6- 6.9 GPa and 62.7 MPa to 33.2-40.8 MPa for Douglas-fir glulam, from 6.0 GPa to 4.4-5.3 GPa and 58.9 MPa to 26.4-42.1 MPa for Southern pine glulam. In addition, the difference between the strength of shear and compression of glulam before and after standard fire exposure test was not significant.