胶合竹顺纹植筋的抗拔性能

选择胶合竹为研究对象,以双组分环氧树脂为胶黏剂,采用拉—拉荷载模式开展胶合植筋连接抗拔性能研究。主要探讨了边距、胶层厚度以及长径比等对植筋连接抗拔强度的影响。结果表明:边距对植筋连接抗拔强度有一定影响,边距过小导致胶合竹开裂,抗拔强度下降,推荐边距应大于4d(植筋杆直径);胶层厚度对植筋抗拔强度影响不显著;长径比是影响植筋连接抗拔强度的重要因子,抗拔强度随长径比的增大而增大,并存在一个临界植入深度使得抗拔强度等于植筋杆屈服强度。胶合竹与胶黏剂粘接界面名义剪切强度随长径比的增大而减小。根据长径比给出植筋抗拔强度预测方程。试验过程中主要产生胶合竹开裂、植筋杆拔出和植筋杆屈服3种破坏模式。

Pull-out Strength for Glued-in Rod Parallel to the Grain of Structural Guled Laminated Bamboo

With structural glued laminated bamboo as study object, we used two-component epoxy to study the pull-out strength of glued in rod, and tested the specimens in pull-pull configuration.We also studied the influence of edge distances, glue thickness and the slenderness ratio on pull-out strength.The edge distances had certain effect on pull-out strength, the pull-out strength was decreased when the edge distance was too small;because the glulam was cracking in this case, the recommended edge distances was 4d ( d is the rod diameter ) .The glue thickness had insignificant effect on pull-out strength.The slenderness ratio has an important effect on pull-out strength.The pull-out strength was increased with the slenderness ratio increasing, and there was a critical embedded depth making the pull-out strength of glued-in rod equal to the yield strength of the steel rod.The nominal shear strength of glulam/adhesive was decreased with slenderness ratio in-creasing.We got the mean pull-out strength of a single axially loaded rod set parallel to the grain.The main failure modes were glulam cracking, shear failure along the rod and yielding of the rod.