Development of Joint Which Enable to Make Strong and Ductile Timber Frame Structures.

在这项研究中，我们打算开发出坚固而延性好的节点方法，用于各种木框架结构的轴心构件之间的连接。首先，对于住宅，采用直径25 mm、长120 mm的小龙骨螺栓(LSB)组成木质斜交体系，不会造成窗台构件的飞溅。通过长91 cm、高273 cm的剪力墙试件的侧向剪切试验，评价了斜交体系的抗剪强度、刚度和延性。试验结果表明，新开发的斜交体系在推拉荷载作用下具有相同的许用强度，但在拉荷载作用下极限强度降低了约10%。其次，重点研究了现有的由钢材较少的节点组成的半刚性连接技术，并通过足尺框架试验对其结构性能进行了评估。作为我们独创的半刚性连接方法，我们研制了直径30 mm、长280 mm的中型LSB，首次在Douglus-Fir GLT上对其抗拔强度和刚度加载性能进行了评估。试验结果表明，平行于颗粒的抗拔刚度比垂直于颗粒加载的抗拔刚度高2~6倍。而侧向加载的极限强度是端面加载的两倍。在任何情况下，强度和刚度与嵌入面积成正比，因此可以从这些实验中确定LSB的允许设计值。最后，对跨度分别为360 cm和270 cm的胶合板半刚性门式刚架试件及其节点均由LSB节点组成的试件进行了水平加载试验，以评价框架结构的抗剪性能。试验结果表明，强度和刚度与预测值基本一致。因此，我们认为得到了结构上合理的接缝方法，使之能够建造坚固且延性好的木结构。

In this study, we intended to develop strong and ductile joint methods which could connect axial members with each other for various wooden frame structures. At first, for the use of residential houses, a small lagascrewbolt (LSB) of 25 mm diameter and 120 mm long was applied for composing wooden diagonal system which did not cause spriting at sill member. Shear strength, stiffness and ductility of the diagonal system were evaluated by lateral shear test on shear wall specimens having 91 cm long and 273cm height. Test results showed that the newly developed diagonal system had same allowable strength for both push and pull loading, but also showed that about 10% smaller ultimate strength wen it was loaded by pull load.Next attentions were paid on the existing semi-rigid jointing techniques which could composed of joints with less steel wares, and their structural performance were evaluated by full-scale frame experiments. As our own original semi-rigid jointing method, we developed medium size LSBs of 30 mm diameter and 280 mm long, their pull-out strength and stiffness loaded performances were first evaluated on Douglus-fir GLT Test results showed that pull-out stiffness parallel to the grain was as higher as two to six times of those compared with perpendicular to the grain loading. While ultimate strength of side grain loading was stronger as two times of end grain loading. In any cases, strength and stiffness was proportional to the embedment area so allowable design values for LSB could be determined from these experiments. Finally, glulam semi-rigid portal frame specimens of 360 cm span and 270 cm height and their joints were all composed of LSB-joints were laterally loaded to evaluate shear performance of the frame structure. Test results showed that strength and stiffness were almost same as those predicted. In consequent, we think that structurally reasonable jointing methods were obtained which enable to built strong and ductile timber structures.