中小徑杉木結構牆之水平剪斷強度評估

Evaluation on Racking Strength of Structural Wall from Small-medium Diameter China Fir

葉民權(Min-Chyuan Yeh)

《林產工業》 19卷4期 (2000/12) Pp. 451-456

摘要

本研究利用杉木中小徑木開發木結構用建材，並組合成結構牆，進行實木牆之水平剪力抵抗評估。試驗中取杉木原木分別製材，窯乾或氣乾後利用環氧樹脂，分別膠合徑面板材製品及對剖製材品成為正方形斷面之角材，利用所組成之角材以大木螺釘施工組成尺寸為1.2m寬×1.8m高之實木牆。試驗結果顯示，組合杉木角材斷面為10cm×10cm者，對剖角材之實木牆在側向力作用下的最大破壞水平剪斷強度為2603kgf/m，較徑面板材之實木牆高近一倍（98.5%），同時也較對照組之正含髓心未氣乾角材所組成之牆面高79.1%。組合杉木角材斷面為12cm×12cm者，徑面板材之實木牆的最大破壞水平剪斷強度為1775kgf/m，分別較徑面板材及正含髓心角材之實木牆高20.1%及20%。組合角材之牆面破壞多屬於大木螺釘之變形以及垂直引拔破壞，而正含髓心牆面則發生在防止劈裂之開槽位置的木材開裂。角材尺寸大小對實木牆水平剪斷強度之影響，除徑面板材外並無明顯差別，在第三階段所得之牆面剪斷剛性係數，以對剖角材牆之1.268×10^5 kgf/m為最高，分別大於徑面角材牆及正含髓心牆面40.9%及64.5%。所開發之對剖角材牆及徑面板材牆之水平剪斷強度分別較9mm厚合板結構牆高197%及90%而有相當的抵抗側向橫力效果。

關鍵字

杉木 ； 剪力牆 ； 水平剪斷強度

並列摘要

Structural lumbers were processed from small or medium sizes of China fir logs and were assembled into structural walls for the evaluation of racking strength in the study. Logs were processed with bandsaw and those quarter sawn and half sawn lumber were then kiln dried and air dried, respectively. Structural wall lumber with rectangular cross section were assembled with epoxy adhesives and then fabricated horizontally with leg screws into 1.2 m (wide) × 1.8 m (height) solid wood walls for shear resistance tests. The results indicated that maximum racking strength of structural wall fabricated with 10 em × 10 em of half sawn wood members is 2603 kgf/m, which is 98.5% and 79.1% higher than that of quarter sawn wood member and pith-contained wood members, respectively. The structural wall fabricated with 12 ern × 12 em half sawn wood members has maximum racking strength of 1775 kgf/m, which is 20.1% and 20% higher than that of quarter sawn wood member and pith-contained wood member, respectively. The major failures of structural wall resulted during lateral load application are mostly due to weak withdrawal resistance and shear deformation of lag screws for half sawn and quarter sawn wood members. While splits occurs near the gaps at the center faces, which are used for preventing split by shrinkage for pith-containedwood member. It seems that the sizes of wall elements has little influence on the racking strength of structural wall except the case of half sawn wood members. Values of shear stiffness for structural walls evaluated during third stage of load application are 1.268×105 kgf/m for half sawn wood member, which is 40.9% and 64.5% higher than that of quarter sawn ~d pith-contained wood members, respectively. Furthermore, racking strength of structural wall fabricated with half sawn and quarter sawn wood members are 197% and 90% higher than that of structural wall sheathed with 9 mm plywood as reported in previous study.

並列關鍵字

China fir ； Shear wall ； Racking strength