應用柳杉結構用直交板於複合工字梁之製造與性能評估

Application of Japanese Cedar Structural Cross Panel on the Composite I-beam Manufacturing and Performance Evaluation

蔡浩章(Hau-Jang Tsai)

指導教授 ： 葉民權

國立屏東科技大學/農學院/木材科學與設計系所/碩士(2010年)

https://doi.org/10.6346/NPUST.2010.00024

摘要

工程用木材在木質結構上為重要之材料，本研究為拓展柳杉造林木之應用及提高木材有效利用率，而進行木質複合工字梁設計及研製，並進一步探討木質複合工字梁之製造技術及條件，在試驗中採用結構用LVL為梁翼材，梁腹材則分別採用自行開發之柳杉直交板及柳杉實木進行實大尺寸工字梁之組合，梁翼與梁腹間之接合設計分別採用自攻螺絲接合、舌槽接合及指榫接合等三種，梁腹材採用24 mm及36 mm二種厚度，並進行梁試體抗彎性能之評估，同時評估柳杉木質複合工字梁在樓板托梁應用之可行性。

在製造條件方面，柳杉材作為直交板時，加壓壓力以10 kgf/cm2有較佳之膠合強度，直交板作為梁腹材時之方向配置，可採用強度較佳之表層木理呈水平方向之條件進行木質複合工字梁組合。在梁翼及梁腹材切削加工條件方面，舌槽接嵌合度以-0.1 mm為最適條件。在切削指榫及指形方面，建議指刀排列方向為並排，以獲得較正確之指端寬。

以最大抗彎承載及抗彎強度而言，以指榫接合且梁腹厚度為36 mm（F-C36）之條件所組成之柳杉複合工字梁有較佳之抗彎承載性能，分別高於舌槽接合及自攻螺絲接合約12-20％；在抗彎剛性及抗彎彈性模數方面，工字梁之梁翼與梁腹間之不同接合設計之間並無顯著性之差異。抗彎剛性之計算必須同時考慮梁腹材之剪斷剛性性能，其中柳杉複合工字梁之撓曲特性約87-94％主要是受到抗彎之影響，而剪斷撓曲量佔總撓曲量約6-10％。在抗彎撓曲之設計限制下，本研究所開發之各組工字梁所能承載之載重值，為最大抗彎破壞值之19-22％，同時，在設計載重條件下所測得之撓曲量均未超過建築技術規範中規定之最大撓曲量，且僅為規定之37-52％；結果顯示，各條件工字梁皆能符合結構性能之需求並可滿足樓板托梁之用途，建議可選用施工簡易且快速組裝之自攻螺絲組合所組成之工字梁。在試驗中藉由應變片量測工字梁載重跨距中央處之應變分布，結果顯示，應變及應力分布大致呈線性關係，其中舌槽接合與指榫接合所組成之工字梁較能傳遞應力於梁翼材上，各組柳杉複合工字梁拉伸側與壓縮側之應變量約有2-22％的差異。

以有限元素分析（Finite element analysis, FEA）模擬複合工字梁之應力及應變分布情形，並加以探討有限有素模型（Finite element model, FE model）對抗彎撓曲量之影響，顯示以立體元素（solid 45）及梁元素（beam 3）二種模型之抗彎撓曲量相差約僅-0.4-5.6％，在分析過程中，採用直交性材料參數可提高約12％之準確性，其分析之應力及應變分布，分析值有高於實測值約37％之情形，但有相似之分布趨勢，其差異性可能是梁腹材為一不連續之材料，另可透過所分析之最大主應力產生位置預測破壞情形，藉以補強破壞處，其增加結構之可靠度。

關鍵字

直交板 ； 自攻螺絲接合 ； 指榫接合 ； 舌槽接接合 ； 木質複合工字梁

並列摘要

Engineered wood is a vital material in the wood-framed structure application. To improve the application of Japanese cedar plantation timber and related effective utilization, a wood-based composite I-beam was designed and developed in the syudy. The manufacturing techniques and requirement of composite I-beam were further investigated. The influence of joint types between flange and web on the flexural properties of wood composie I-beams fabricated with structural LVL flange was investigated. The web materials included Japanese cedar cross panel and solid wood. The I-beams assembled with coach screw, tapered tongue and groove, and finger joint, and the web thickness used either 24 mm or 36 mm were tested flexurally based on the third-point load.

As a results of Japanese cedar cross panel assembly with a press machine, the optimal conitions were found to be 10 kgf/cm2 as the pressure application. The web orientation during the assembly were placed in horizontal direction for surface grain of cross panel resulting in better strength. Fitnesses of tapered tongue and groove joints between flange and web members was -0.1 mm.

The maximum static flexural loading capacities and MOR of finger joint and web thickness 36 mm（F-C36）I-beams fabricated with finger joint were 12 to 20% higher than those fabricated with either tapered tongue and groove or coach screw. There was no significant influence in bending stiffness and MOE of I-beam among three different joint types. The calculated values of bending stiffness agreed well with their measured values; therefore the bending component 87-94% and shear component 6-10% in the flexural deflection could be calculated with high accuracy. Flexural loading capacities under the limitation of the design deflection for I-beams specified in the code were between 19 and 22% of the maximum bending loads at failure. All deflection measurements of Japanese cedar wood composie I-beams were lower than the limitation specified in the code and ranged between 37 and 52%. Result of wood composie I-beams showed satisfied loading capacity. The linear relationship of strain distribution on the cross section of I-beam subjected to a flexural load can be found at the central load span based on the measurements of strain gages. It is indicated that there is 2-22% differerce between tensile and compressive strain.

The simulated stress and strain distribution and flexural deflection of a composite I-beam using finite element analysis (FEA) with FE model was performed. There are only -0.4-5.6％ of the flexural deflection difference between FE models using solid element and beam element. Simulation results from FE model containing orthotropic material properties were 12％ higher than calculated flexural deflection. The simulated stress and strain which were 37％ higher than the measured values may be due to the discontinouity and variability of web materials. However, the principal stress forecasted reasonably with the actual failure on Japanese cedar composite I-beam.

並列關鍵字

Cross panel ； Coach screw ； Finger joint ； Tapered tongue and groove ； Wood composite I-beams

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