Embedment Performance of Glued Laminated Bamboo and Timber Composite Joints

Dowel connectors are extensively utilized to establish joint connections in timber constructions. This study investigated the embedment performance of glued laminated bamboo and timber composite joints through half-hole tests, focusing on the effects of dowel diameter, loading direction, contact condition, combination method, and moisture content. The experimental results indicated that the embedment strength of the specimens decreased progressively with an increase in dowel diameter. For wood-bamboo-wood (WBW) specimens, the embedment strength in the longitudinal to the grain was 18% higher than in the transverse direction. For bamboo-wood-bamboo (BWB), the embedment strength in the longitudinal to grain was 71% higher than in the transverse to grain. However, the compression direction to the grain had no observable impact on the embedment stiffness. The embedment capacity varied with different combination methods of bamboo and wood materials, and BWB specimens exhibited greater strength than WBW specimens. For WBW specimens, the embedment strength under smooth contact conditions was 61% higher than that under threaded contact conditions. Similarly, for BWB specimens, the embedment strength under smooth contact conditions was 73% higher than that under threaded contact conditions. After 3 days of water immersion, the embedment strength of glued laminated bamboo and timber composite specimens decreased to about 45% of the original strength. After 6 days of water immersion, the embedment strength of glued laminated bamboo and timber composite specimens fell to about 15% of the original strength. Based on the test results, this paper proposed calculation methods for predicting the embedment strength and stiffness of glued laminated bamboo and timber composite joints.