Members used for the Korean traditional joints have been processed by handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increasedby handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increased by two times with shear failures on the tenon than the control specimens. The maximum tensile strength was obtained in the specimen of 25 degrees, and no difference was observed in the changes of neck widths.
The glulam is determined by, and therefore a representation of, a new kind of ecological structural materials. The aim of this study was to summarize the mechanical performance especially the flexural behavior of various kinds of glulam and the physical properties of their relevant original timbers including pseudotsuga menziesii, larch, Yi poplar, poplar, China fir, mongolian scotch pine and camphor. And then it established and analyzed the relationship between the two to contrast those timber species so as to provide engineers with some reference in selecting timber glulam.
The new observation tower on the Pyramidenkogel (Keutschach, Austria) has a spatial frame structure, with three main components: 16 glulam larch wood supports; 10 elliptic steel rings; and 8 diagonal steel struts.
The basic geometry of the tower consists of a series of ellipses (major axis 19 m, minor axis 11
m) arranged in such a way to rotate by 22.5° from floor to floor. The height of the tower is 100 m;
the highest visitors’ platform is at height 71 m.
Recently, the numerical value and the technical information of the design are insufficient though an increase of a large timber construction is expected. In this research, a high load carrying capacity shear wall with thick plywood sheathings for the large timber construction was developed, and its static bearing force was confirmed experimentally. And the bearing force of the shear wall was calculated by using past numerical analysis methods. As a result, the development of the wall having the target bearing force succeeded, and the numerical analysis method could be applied to the high load carrying capacity shear wall.
For enhancing productivity of glulam, high frequency (HF) curing technique was researched in this study. Heat energy is generated by electromagnetic energy dissipation when HF wave is applied to a dielectric material. Because both lamina and adhesives have dielectric property, internal heat generation would be occurred when HF wave is applied to glulam. Most room temperature setting adhesives such as phenol-resorcinol-formaldehyde (PRF) resin, which is popularly used for manufacturing glulam, can be cured more quickly as temperature of adhesives increases. In this study, dielectric properties of larch wood and PRF adhesives were experimentally evaluated, and the mechanism of HF heating, which induced the fast curing of glue layer in glulam, was theoretically analyzed. Result of our experiments showed relative loss factor of PRF resin, which leads temperature increase, was higher than that of larch wood. Also, it showed density and specific heat of PRF, which are resistance factors of temperature increase, were higher than those of wood. It was expected that the heat generation in PRF resin by HF heating would occur greater than in larch wood, because the ratio of relative loss factor to density and specific heat of PRF resin was greater than that of larch wood. Through theoretical approach with the experimental results, the relative strengths of ISM band HF electric fields to achieve a target heating rate were estimated.
In a process before being finished in a sawing factory after felled in forest, we clarified the actual situation of the carbon income and expenditure with edge materials and the fuel, and calculated the carbon balance of the house made by Nagano’s local wood. In this report, we carried out the actual survey and a hearing investigation in the laminated lumber factory and, calculated carbon balance of Japanese larch finger joint wood and glued laminated timber of eastern Nagano prefecture.
Behaviours of Larch Glued Laminated Timber Beams Exposed to Standard Fire Heating During the Cooling Phase Study on Fire Performance of Structural Glued Laminated Timber Beams Part 1
Architectural Institute of Japan Structural System
Summary
Timber elements, which are different from other structural elements, have a characteristic problem in that the load bearing capacity decreases due to self-burning in the case of a fire, and this self-burning may continue after other fuel in the room has been exhausted. Therefore, the structural fire performance of timber elements should be clarified during not only the heating phase, but also the cooling phase. However, in examining the load bearing capacity of timber elements in a fire, few studies have considered the cooling phase. In the present paper, the fire performance of glued, laminated timber beams is discussed based on load-bearing fire tests that take the cooling phase into consideration.
Process parameters of cross-laminated timber (CLT) fabricated with Japanese larch were evaluated. The process parameters were designed by using an orthogonal test including pressure, glue consumption, and adhesive. Both delamination and block shear tests were conducted on CLT in accordance with GB/T 26899 (2011). The results showed that the optimum process parameters were A2B3C2 including pressure (1.2 MPa), glue consumption (200g/m2), and amount of sdhesive (one-component plyurethane). The weight loss and moisture absoption increased when the temperature increased, but the block shear strength decreased as the temperature was raised from 20C to 230C.
Japanese larch (Larix kaempferi) is an important species in China. The extensive use of Japanese larch can alleviate lumber shortage in China. Various grades of Japanese larch (Larix kaempferi) laminas were chosen to study the factors that affect the bolted joint performance. By comparing the loading test results with the required design values,it revealed that: (1) Bolt diameter affected the loading performance, then, bolt class, and the lamina grade was the least influential factor. (2) Japanese larch glulam can achieve the required designed value to be used as structural materials.
In the past study, we conducted compression tests with laminated veneer lumber of Japanese Larch. We observed the deflection and strain behaviour. As a result we could evaluate the bucking strength with Euler’s equation and Tetmajer’s method. For structural design we should expand the versatility of that method. Three wood species for structural members would be selected for these tests. Those were Japanese larch, Japanese cypress and Japanese cedar. For the test parameter, we set the 8types of slenderness ratio for the compression test and we conducted monotonic compression tests with pin-supported on both edges. For the mechanical properties we conducted compression tests with short column members and got yield compression for those materials. In the compression tests, we could see the bending deflection. We would get the ratio the maximum strength and yield strength for distinguish the limited slenderness ratio. As a result it was cleared that the limit slenderness ratio of these wood species was 100. And we could confirm that the Tetmajer’s method is useful for evaluation the yield strength.
