Effect of Moisture Content in Rubberwood with Heat Treatment on the Performance of Glued-laminated Timber Beams under Sustained and Cyclic Loads

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Publication Details

Author list: Thippakorn Udtaranakron; Warawit Eakintumas; Tawich Pulngern

Publisher: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าพระนครเหนือ

Publication year: 2024

Volume number: 34

Issue number: 3

Start page: 1

End page: 14

Number of pages: 14

ISSN: 2985-2080

eISSN: 2985-2145

URL: https://ph01.tci-thaijo.org/index.php/kmutnb-journal/article/view/257658

Abstract

      This research focuses on the effect of moisture content (MC) of rubberwood with heat treatment on the flexural properties, creep, and cyclic load behaviors of glued-laminated timber beams and presented the experimental results of rubberwood glulam beams with MC of 7.73% and 6.26% in comparison with that of control rubberwood glulam beams with MC of 9.66%. In the case of flexural properties, modulus of rupture in case of rubberwood glulam with MC of 6.26% and 7.73% which MC was reduced from the control wood about 19.98% and 35.20% decreased significantly of 8.57% and 46.72%, while the modulus of elasticity was slightly changed. For the sustained load test, the rubberwood with various MC was considered by varying stress levels for the duration of 1,000 hrs. The maximum relative creep of rubberwood glulam was 0.310 which was lower than natural timber. However, the relative creep of rubberwood glulam with MC of 6.26% and 7.73% for stress level of 55% were significantly decreased to 47.27% and 42.27%, respectively.      The results indicated that variation of MC in rubberwood glulam directly influenced the value of relative creep, especially for the high-stress level. The longer time of sustained load test for the duration of 1 year was also investigated for specific stress levels and found that the power-law creep model which was used in case of 1,000 hrs could be used for the long-term creep response prediction of rubberwood glulam.      The results from the cyclic loading test also demonstrated that the energy dissipation of rubberwood glulam with MC of 6.26% and 7.73% in comparison with the control glulam reduced to be 21.05% and 82.51%, respectively. The reduction of MC in rubberwood affected significantly in the case of energy dissipation and the impairment of strength of rubberwood glulam. This study indicates that thermally modified rubberwood glulam with MC of 7.73% is the suitable moisture content for structural members. This moisture content affects slightly the mechanical properties and gives better dimensional stability and weather resistance.

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