부산대학교 도서관

The design of timber connections is of great importance since their performance is decisive for timber structures. The widely adopted technique utilizing the slotted-in steel plates could possibly be replaced by using timber-based gusset plates due to the significant advantages in terms of the environmental impact, economy, ease of prefabrication, and fire resistance of the latter one. Among the timber-based panels, plywood made of birch was chosen in the study due to the combined benefits of the cross laminated configuration of plywood and the superior mechanical properties of birch compared to most softwoods. In this paper, a preliminary experimental investigation was carried out to study the structural performance of the glulam trusses connected by means of bonded birch plywood gusset plates. Tests were performed on ad-hoc designed frame-like specimens. The plywood gusset plates were under-designed to be the weakest link in the structure, so as to study their load-bearing capacity. The knowledge obtained in this study is the first step towards the establishment of a model for the design of truss nodes with bonded plywood gusset plates. In the study, the face grain orientation of birch plywood was varied (0°, 5°, and 15° to the horizontal axis) in three test series. Test results show that the influence of the face grain angle from 0 to 15 degrees on the global stiffness of the frame structure is insignificant and it can be well predicted by a simplified planar 2D numerical models. Two analytical models, namely, the classic so-called 'Whitmore model' along with a more accurate analytical model, were utilized to illustrate the failure mechanism of birch plywood gusset plates with the concept of the effective width and the spreading angle.