| Summary: | 碩士 === 國立屏東科技大學 === 木材工業系 === 92 === Abstract
【Abstract】The actual sizes of 2.44×3.65 m wood-framed walls were constructed with light-framing approaches in the study, while the wall sheathed with Lauan plywood panels and the frames assembled with SPF structural lumbers. The horizontal shear performance of walls with various opening types subjected to the cyclically lateral load procedures were investigated, and the effect of bracing angles were also included. The results indicated that the racking strength of walls with 120, 160, and 200 cm window openings were only slightly lower than that of the walls subjected to monotonic load application, while the shear stiffness were significantly reduced about 32%, 37%, and 36%, respectively. Similarly, there was 26% lower in shear stiffness for the walls with double 80 cm-wide door openings subjected to cyclically lateral load application. However, both the values of racking strength and shear stiffness for the walls with single 80 cm-wide door opening or 200 cm-wide garage opening were not reduced in comparison to those of walls subjected to monotonic load application. Both the racking strength and shear stiffness of the wood-framed walls with door openings were 23% lower than those of the walls with window openings under the same opening width conditions, and the values of toughness was also 25% lower. The deformation around openings of the wood-framed walls can be improved through the reinforcement at the corners of openings using steel bracing angles. The racking strength and shear stiffness of the walls with double door openings are increased 19% and 30%, respectively, by putting the bracing angles at the corners of openings. The strain energy of the walls with 160 cm-wide and 230 cm-wide window and single door openings increased 11%, 17%, and 17%, respectively.
The damping energy and strain energy of walls was reduced as the percentage of opening area increased. The highest damping energy is 90 kgf-m for the wall with 120 cm-wide window opening and the lowest was 54 kgf-m for the wall with 200 cm-wide garage opening. Furthermore, as the shear stiffness of walls increases, the strain energy also increases. The values of coefficient of determination is high between maximum shear stiffness and damping energy or strain energy as the wall reached to the displacement of limit state at failure. The damping energy and strain energy of walls sheathed with gypsum board was the same as the plywood sheathed wall before the lateral displacement stage of 27.2 mm, but the strain energy was lower than that of the plywood sheathed walls due to the tendency of deformation for gypsum board sheathed walls.
The values of stress analysis of wood-framed wall with openings by using finite element method showed more accurate in x direction, and deviation in y direction due to the cross grain failure of sheathed panels possibly, which resulted the simulated values higher than the measured values. However, the magnitude of stresses around the corners were still acceptable in accuracy, and the locations of stress concentration were also matched with the actual failure positions at the wall.
【Keyword】Cyclic lateral load, Racking strength, Shear stiffness, Strain energy, Damping energy, Finite element analysis.
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