Structural joints with glued-in hardwad dowels

研究了硬木胶合榫桩与基础节点的抗弯矩性能。用硬枫木制成的直径为12毫米的销子，用聚氨酯胶粘剂粘在糖胶合木的柱和基板上，制成接头标本。假设节点因销子抽离而破坏，考虑销子抽离力和垂直于基板晶粒的压应力，对节点的抗弯矩强度和刚度进行了预测。单个销钉的抗拔强度和刚度均来源于前人的试验。节理试件的试验表明，通过合理选择节理区域的销钉布置，可以控制节理区域的抗弯矩强度和刚度。在接头区域的外侧布置销钉可获得最大的强度。在这种情况下，强度和刚度的预测与实验结果吻合得很好。计算中过高估计了内部带销钉的接头的强度和刚度。原因可能是：节点边缘的压应力超过弹性极限，中性轴向受拉侧移动，导致销钉的拉拔力比假设受压侧有弹性时计算的要大。此外，当关节剧烈旋转时，弯曲力会作用在销钉上。通过桩接框架的机架试验，验证了其作为剪力墙的性能。无支撑框架试件的试验结果表明，试验强度与基于节点弯矩分布的刚连接框架计算值吻合较好。带支撑的试验样品因支撑的鸭化而失败，这表明销子具有足够的拉拔强度，可与金属紧固件相媲美，用于桩与基础的连接。

Moment-resisting properties of post-to-sill joints made with glued-in hard-wood dowels were studied. Dowels of 12 mm in diameter made of hard maple are glued into post and sill members of sugi glulam with polyurethane adhesives to make joint specimens. Assuming that joints fail by withdrawal of dowels, moment-resisting strength and stiffness of joints were predicted by considering withdrawal force of dowels and compressive stress perpendicular to the grain in a sill members. Withdrawal strength and stiffness of single dowels were derived from previous experiments. Tests of joint specimens showed the possibility of controlling moment-resisting strength and stiffness by choosing proper arrangements of dowels in the joint area. The greatest strength was obtained by arranging dowels in the outer section of the joint area. In this case, predictions of strength and stiffness agreed well with experimental results. Strength and stiffness for joints with dowels in the inner section were overestimated by the calculations. The reason may be explained as follows : The compressive stress at the edge of the joint area exceeded the elastic limit and the neutral axis moved toward the tension side, which caused a larger pull-out force for the dowels than calculated assuming elastic behavior on the compression side. Furthermore, bending forces would act on dowels when a joint rotated significantly. Racking tests of dowelconnected frames were conducted to verify their performance as shear walls. The test results of frame specimens without braces showed good agreement between experimental strengths and calculated estimations based on moment distribution among joints assuming rigid-joint frames. Test specimens with braces failed by duckling of the braces, which showed sufficient withdrawal strength of the dowels comparable to metal fastners for post-to-sill joints.