| Summary: | 博士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 95 === 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.
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